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Eye Health
Advis­­­­or
®
A magazine from Johnson & Johnson Vision Care
Full Vision
Correction
EDITION ONE 2012
Eye Health
Advisor
CO NT ENT
Introduction
Eye Health Advisor®
A magazine from Johnson & Johnson Vision Care
EDITION ONE 2012
2Introduction
3
Full Vision Correction – The
International Perspective
by Christina N Grupcheva
7
Pathogenetic Characteristics
of Full Vision Correction of
Myopia
by Igor Kornilovsky
12
Full Refractive Error
Correction- the Past, the
Present and the Future
by Marek Habela
16
Top 10 Questions on
Full Vision Correction
Answered by Eye Care
Professionals
T
his issue of the Eye Health Advisor ® newsletter is dedicated to full vision
correction. We try to live in a perfect world, but to see it we need "optimal"
vision… Is this possible today? Historically, some of us have been taught and
encouraged that myopia should be hypo-corrected… This concept was taken
as standard for so long that some patients believe it is better to have a “weak”
correction to prevent laziness of their eyes. Recent research has highlighted
some of the harmful effects of improper correction and hypo-correction.
Although the world is unified by the informational bank of the internet, it is
very difficult to set international standards that will postulate standardized rules
for prescribing. Moreover, glasses and other optical means of correction are
based on subjective refraction and the acceptance of certain parameters. In
such a complex situation everyone should make customized decisions for each
case. This issue is specially designed to assist in understanding the importance
of full vision correction and provides information on how to deal with several
controversial issues. Three international experts summarize their experience and
answer important questions. To complete the picture, recognized experts share
their views on specific points regarding full vision correction.
Professor Grupcheva, who practices in Bulgaria, gives a detailed overview of
the international perspective on full vision correction, including recent insights
from the World Congress of Ophthalmology held in Abu Dhabi, in February of
2012. The highlight of the article is the disparity between perfect vision, full vision
correction and subjective appreciation, which is in fact more complex because
of public opinion and the different schools of thought. A very interesting point
of view is also presented by the Russian academic, Professor Igor Kornilovsky.
His opinion is based on his long-term clinical observations of a large number of
patients with varying degrees of myopia, with or without full correction. This
extensive work has led him to many conclusions. The most important being that
full vision correction of myopia facilitates minimal dispersion of light inside the
eye, better formation and functioning of accommodation reflex and optimizes
the relationships between accommodation and accommodation-convergence
ratios. A practicing ophthalmologist with more than 30 years of clinical practice,
Dr Marek Habela from Poland, presents his thoughts on the best approach
for full vision correction. He puts an accent on an individual approach with
different algorithms for different refractive errors. His most interesting tool is
the application of adaptive optics on full vision correction. Last but not least, the
top 10 questions answered by established expert clinicians complete the picture
and provide invaluable practical tips for a better, patient oriented clinical practice.
This issue of the Eye Health Advisor ® newsletter was designed to encourage
active Improvement of full vision correction by eye care practitioners, not only
as a prescription but also as a philosophy and public awareness. Better, clearer
vision has more than direct benefits, it has a significant long-term social impact!
2
Eye Health
Advisor
A magazine from Johnson & Johnson Vision Care
Full Vision Correction – The International
Perspective
Christina N Grupcheva
Introduction
Refraction is one of the most commonly performed
examinations by the eye care practitioner. It is compulsory
and consists of objective and subjective components.
Objective refraction approaches the eye as an optical
system, in order to precisely measure the deviation from
perfect focusing (emmetropia).1 Subjective refraction is
based on visual acuity and is a process of determining
correction (highest plus and lowest minus lens and/
or toric lens for correction of astigmatism) in order to
achieve best vision. However, the standards for prescribing
on the basis of subjective and objective refraction vary
considerably between eye institutions. Furthermore in noncommunicative patients it is widely accepted to prescribe on
the basis of objective refraction.2 As those cases are usually
pre-verbal children, mal-correction might be associated with
retarded development of the immature visual system and
also might have serious social consequences. Although it
is a “routine” procedure, refraction is a very challenging
part of the eye examination, especially when precise vision
correction has to be made. There are considerable variations
in prescribing habits around the world, mainly related to the
incorrect but well established, dogma that myopia requires
hypo-correction.1-3 The problem is considerably aggravated
by the fact that there are many people who accept their
vision as normal and do not actively search for, and often
even refuse, correction. The latter is typical for low income
individuals and for children and teenagers. The occurrence
of undercorrection is so significant, that uncorrected vision
appears to be the most common eye problem in any culture
and any country.
This overview is the author’s interpretation of the published
literature and the habits in prescribing based on her 20
years of experience in refraction and optical correction.
In fact, during those years there were changing trends
and also “westernization” of the habits in South-Eastern
Europe. Contemporary modes of information exchange
and continuous education allow eye specialists in the
world to apply world knowledge and the experience of
peers from any country instantaneously. Today, world
eye care practitioners are united in understanding that full
vision correction, together with meticulous correction of
astigmatism, is most beneficial for the patient not only for
provision of good vision but also as a guarantee of quality
of life at any age.
EDITION ONE 2012
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Professor Christina N Grupcheva MD,
PhD, DSc, FEBO, FICO(Hon)
Prof CN Grupcheva is
a full National Professor
in Ophthalmology and
Head of the “Department
of Ophthalmology and
Visual Science” at the
Medical University in
Varna, Bulgaria. She
is Associate Director
of the Specialised Eye
Hospital in Varna, and
runs a private premium
refractive practice. Her clinical and research
interests and expertise are related to refraction,
cornea, anterior segment, tear film, in vivo confocal
microscopy, contact lenses and complex anterior
segment surgery. She has published more than
120 scientific papers and 14 ophthalmology books.
Professor Grupcheva teaches at all graduate and
postgraduate levels and supervises 5 PhD students
and 10 residents in ophthalmology. She regularly
presents at national and international meetings on
subjects related to her field of expertise, mainly as
an invited speaker. She is a member of a number
of Bulgarian, European and International learned
societies. During her career in research she has
received more than 350,000 Euros in research
grants, including a FNI grant 2010.
Importance of vision correction
Uncorrected refractive error accounts for half of the global
burden of avoidable vision impairment and nearly a third of
the global burden of avoidable blindness.3 Globally, 153 million
people have visual impairments, or are blind due to uncorrected
refractive error and the majority live in low income countries.
Under-corrected refractive error can account for as much
as 75% of all impaired vision in high income populations,
markedly affecting quality of life. Full vision correction may
be achieved with glasses, contact lenses or refractive surgical
procedures. Contact lenses have the advantage of excellent,
stabile and invisible correction, which is completely reversible
and allows fine tuning at all times.
3
Because of the importance of refraction for the wellbeing of people the Wolrd Health Organization (WHO)
has developed a guide with recommended steps in the
provision of refraction services, which are as follows:
498
Pre prescribed
Newly prescribed
388
Step 1: C
ase detection identification of
individuals with poor vision that can
be improved by correction;
Step 2: E
ye examination: to identify
coexisting eye conditions needing
care;
221
179
158
86
Step 3: R
efraction: evaluation of the patient
to determine the correction required;
Step 4: D
ispensing: provision of the
correction, ensuring a good fit of the
correct prescription;
Step 5: F
ollow-up: ensuring compliance with
prescription and good care of the
correction, repair or replacement of
spectacles if needed.
25% vs 56%
14% vs 25%
61% vs 19%
Myopia
Hyperopia
Astigmatism
Figure 1: Analysis of previously prescribed glasses and those prescribed
during the study, demonstrating that pre-prescribed glasses
were mainly for correction of spherical ametropia (myopia and
hyperopia), however, the corrections prescribed during the
screening process were mainly for astigmatism (61% of all cases).
It appears that those guidelines are not applicable for
countries with low socioeconomic development, but for
all “in the field” eye care services, such as prophylactic
and screening programs.
Those steps were followed by many studies, including
one in Bulgaria. The Specialised Eye Hospital in Varna,
Bulgaria in partnership with ORBIS Int (124-128 City Road
LONDON) and using an unrestricted grant from Ronald
McDonald House Charities, conducted a screening that
targeted 10,000 school Children aged 7-12 years old, over
a period of 2 years. The protocol included on site screening
based on uncorrected visual acuity, comprehensive eye
exams for all children with vision below standards and
prescribing full vision correction for all children who needed
it (unpublished data). 9,657 children from the target group
were screened. From those, 993 children (10.3%) were
identified with under-corrected or uncorrected visual acuity
in one or both eyes and subsequently were examined in
the eye department. After comprehensive examination,
632 children were identified with refractive errors and were
prescribed glasses. From the primary screening, another
898 children already wearing glasses were also examined
following the protocol and the glasses of 234 children
were adjusted. When comparing the newly prescribed
and previously prescribed correction, an obvious disparity
for correction of astigmatism was highlighted (Figure 1).
The study concluded that 16% of school children aged
7-12 years old require optical correction. Approximately
7% of children are not corrected for their refractive errors.
Astigmatism is properly corrected in only 1/3 of the cases.
As the study included questionnaires to the parents, it also
highlighted that 35% of parents never knew anything about
regular eye examinations at school age.
4
Examination of a child part of the programme of Specialised Eye Hospital Varna, Bulgaria in partnership with ORBIS Int.
Full vision correction with contact
lenses in the “era of aberrations”
Although full correction is recommended for children,
it is an accepted practice to use a spherical equivalent
power, as an alternative contact lens correction for those
patients with lower amounts of astigmatism. This is driven
by a number of arguments mostly related to cost and
easier fit. Nevertheless, the blur caused by one diopter
of uncorrected astigmatism can reduce acuity of 6/6
to that of about 6/8. This is usually deemed acceptable
in terms of monocular acuity, often retaining a good
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binocular acuity. However, in special activities this might
be associated with visual disturbances. In a small study,
Nilsson et al. proved that monocular astigmatic blur in
the amounts of -0.75 and -1.25 did not have a significant
effect on tested subjects with regard to the amount of
blur or axis orientation.4 Therefore, those authors believe
that spherical equivalent contact lenses in only one eye
are a viable option for low amounts of astigmatic error.
However, there is still no randomized trial demonstrating
the pros and cons of such a compromise.5
In clinical practice nowadays, we recognize two different
levels of aberrations: macro-aberrations (spherical and
astigmatic) and micro-aberrations. The latter are the basis
for the very popular concept of reducing various optical
imperfections and provide a clearer image. It is applied in
many high-tech optical systems and in refractive surgery
as well. However, one must take into consideration that
the optical surface is covered by a dynamic element –
the tear film. The effect of the mathematically calculated
High Definition (HD) optical aids could be completely
compromised by an unstable tear film of poor quality.
Although research is directed towards high technology
in clinical practice, we should utilize contemporary
abilities for full vision correction of macro-aberrationsspherical errors and astigmatism. The well established
concept that hypo-correction is advisable, has been
proven to be wrong. In our soft contact lens study
of over 30 children aged 8-14 years old, followed
for a minimum of 18 months (18-39 ), we found
that progression of myopia has a mean of 0.34D
per year in spherical correction and 0.23D per year
in full spherical and astigmatic correction. In this
group we corrected only astigmatism over 1.00D
(unpublished data). Although, the collected data is not
Precise determination of refraction with digital phoropter is very attractive
for teenagers.
EDITION ONE 2012
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statistically significant, they highlight the importance
of full optical correction in the young population.
It is interesting to highlight that there is a higher
prevalence of astigmatism at birth. Up to 69% of
full-term newborns have astigmatism of one or more
diopter. 6 This however, decreases during the first year,
but still 8-30% have 1.00D or more of astigmatism at
one to two years, 4-24% at three to four years and
2-17% at six to seven years. Therefore, correction of
astigmatism appears to be an important issue for many
young children. Moreover, the young patients should
be trained to evaluate their visual quality and report
fluctuations and decreased visual acuity, as the eye
practitioner cannot count only on parental monitoring.
The International PERSPECTIVE
In the recent World Ophthalmology Congress in Abu
Dhabi (February 16-20, 2012) several sessions on full
vision correction in children were conducted. Those
presentations were directed towards the criteria for full
vision correction in pre-verbal children on the basis of
different rules set by societies such as the American
Academy of Ophthalmology, the American Academy
of Optometry and the Royal College of Ophthalmology.
Currently, there is no unified international standard and
guidelines are partially based on research, as well as clinical
opinion. Basically, it depends on the type of refractive
error. For hyperopia during the first year, the cut off point
for prescribing is 3.50D. However, the recommendation
is to prescribe one diopter less. At the age of 4 years old,
hyperopia of 2.50D must be considered for correction, but
at age of 6 this value drops to 1.50D. For myopia however,
up to the first year of age, the correction is performed only
over -5.00D of myopia, but reduced by 2.00D. Interestingly,
less than 1% of children at that age will have more than
4.00D of myopia. Later in life and up to school age,
myopia over -2.00D should be corrected, but correction is
reduced by 0.5 - 1.00D. At early school age (over 5 years
old) full myopia correction is recommended. Of course
one should consider cases with esotropia and either
reduce the correction or prescribe progressive lenses. The
correction of astigmatism is even more challenging. During
the first year of life astigmatic correction is considered for
cases over 2.50D, and is usually reduced to half of the
measured astigmatism. According to Atkinson et al. the
danger of meridional amblyopia at this early age is a good
reason for at least partial correction.7 Later in life, oblique
astigmatism is more a potent amblyopic stimulus. As the
child gets older, astigmatism must be corrected close to
the measured value, with full correction at the age of 8.
Last but not least, anisometropia should be handled with
extreme care as it could be associated with a stimulus for
amblyopia. Anisometropia of more than 3.00D must be
corrected at any age, but at school age any anisometropia
should be corrected.
5
satisfaction with correction. Using this questionnaire, Hays
et al. demonstrated that emmetropes tended to score
significantly better on the NEI-RQL scales than myopes
and hyperopes.10 They also concluded that the instrument
appears to be useful for comparisons of people with
different types of correction for refractive error. Therefore
full vision correction is a crucial component for good quality
of life and must be the goal of every eye care professional.
Conclusions
One of the international teams presenting on vision correction with contact
lenses at the WCO, Abu Dhabi 2012.
Social impact of insufficient
correction
By visual function, we mean psychophysical measures of
the sensory capability of the visual system, such as visual
acuity or contrast sensitivity. Functional vision is used to
refer to how the person as a whole, is able to use vision in
performing everyday tasks, which are dependent on vision.
Vision is a brain function, and poor vision might trigger
various central and peripheral compensatory mechanisms
leading to adverse reactions such as eye ball elongation.
Many experimental animal and some human studies
highlight peripheral defocus as the main reason for myopia
progression.8,9 Furthermore, insufficient correction may
also have cosmetic and social impacts, starting with poor
vision, inadequate facial expression, behavioral changes,
etc. Therefore the role of the eye care practitioner is not
only to identify the refractive errors, but also to consult the
patient and their relatives on all the available corrections
and the consequences of refusing said corrections. At
different ages impaired visual function might have specific
outcomes. At a very young age, it might lead to eyeball
elongation and amblyopia. At school age the changes
may be more behavioral, like poor performance in class
and poor social skills. Active adults with uncorrected
vision might have poor work performance, negativism and
unwanted facial expressions. In older people, poor visual
function is directly related to depression.
Feedback on full vision correction
Last but not least, quality of life is a very important
reason for full optical correction with more complex optical
aids. Quality of life is usually assessed by questionnaires.
One of the most popular instruments is the National
Eye Institute-Refractive Error Quality of Life survey (13
NEI-RQL) scales, with power to asses clarity of vision,
expectations, near vision, far vision, diurnal fluctuations,
activity limitations, glare, symptoms, dependence on
correction, worry, suboptimal correction, appearance, and
6
Eyesight is the most important human sense. However,
the eye is not perfect and due to various inherited
and environmental factors most eyes present refractive
errors. Human subjects are not always aware that their
vision is below the required standards. The role of the
eye care practitioner is not only to identify the refractive
errors, but also to correct them precisely in order to
provide the individual subject with maximal, useful vision.
Modern technology offers optical aids for the correction of
most of the known optical imperfections. Knowledgeable
application of those means will assure high quality of life
for our patients directly or will serve to prevent further
refractive change in the younger population. Special
attention must be given to youngsters, as their vision might
be the basis for future successful social development.
References
1. Rosman M, Wong TY, Tay WT, Tong L Saw SM. Prevalence and
risk factors of undercorrected refractive errors among Singaporean
Malay adults: the Singapore Malay Eye Study. Invest Ophthalmol
Vis Sci. 2009 Aug;50(8):3621-8. Epub 2009 Mar 5.
2. Rabin J.Correction of subtle refractive error in aviators. Aviat
Space Environ Med. 1996 Feb;67(2):161-4.
3. Dandona L, Dandona R.What is the global burden of visual
impairment? BMC Med. 2006 Mar 16;4:6.
4. Nilsson A, Nilsson M, Stevenson SB, Brautaset RL.The influence
of unilateral uncorrected astigmatism on binocular vision and
fixation disparity. Strabismus. 2011 Dec;19(4):138-41.
5. Wills J, Gillett R, Eastwell E, Abraham R, Coffey K, Webber
A, Wood J.Effect of simulated astigmatic refractive error
on reading performance in the young. Optom Vis Sci. 2012
Mar;89(3):271-6.
6. Wildsoet CF.Active emmetropization--evidence for its existence
and ramifications for clinical practice.Ophthalmic Physiol Opt.
1997 Jul;17(4):279-90.
7. Atkinson J, Anker S, Bobier W, Braddick O, Durden K, Nardini
M, Watson P.Normal emmetropization in infants with spectacle
correction for hyperopia. Invest Ophthalmol Vis Sci. 2000
Nov;41(12):3726-31.
8. Swarbrick HA.Orthokeratology review and update. Clin Exp
Optom. 2006 May;89(3):124-43.
9. McBrien NA, Gentle A, Cottriall C.Optical correction of
induced axial myopia in the tree shrew: implications for
emmetropization. Optom Vis Sci. 1999 Jun;76(6):419-27.
10.Hays RD, Mangione CM, Ellwein L, Lindblad AS, Spritzer
KL, McDonnell PJ. Psychometric properties of the National
Eye Institute-Refractive Error Quality of Life instrument.
Ophthalmology. 2003 Dec;110(12):2292-301.
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Pathogenetic Characteristics of Full Vision
Correction of Myopia
Igor M Kornilovsky
Professor Igor Mikhalkovich Kornilovsky
MD, PhD, DSc.
Professor at the Department
of Ophthalmology, Institute
of Postgraduate Medical
Education; Consultant at
the Clinical Ophthalmology
Department of the National
Medical Surgery Center named
after N.I. Pirogov; Doctor of
Medical Sciences, Professor,
Academician of LAS RF.
Professor Kornilovsky graduated from the Faculty
of Medicine at Krasnoyarsk State Medical University
(Russia) in 1974 and he completed the one-year internship training in ophthalmology at the same university.
While working as an ophthalmologist he was awarded
his M.D. degree in 1979 for his M.D. thesis on the topic
of “Experimental and clinical development of the test
and method to evaluate the functional state of blood
vessels in the eye”. In 1981, Professor Kornilovsky
moved to Moscow where he worked for many years at
the Federal IRTC “Eye Microsurgery” complex named
after S.N. Fedorov. In 1995 he was awarded the degree
of doctor of medical sciences for his doctorate thesis
on the topic of “Eximer-laser for treating corneal pathology”. That was the first doctorate thesis in Russia on
the eximer-laser microsurgery in treatment of corneal
C
urrently, the best approach for correcting myopia
is debatable. The answer to this question is extremely
important because amongst refractive errors, myopia is
the leader and often associated progression can lead to
complications. In recent years, clinical ophthalmologists
in Russia have been recommending not to fully correct
myopia. This was based on the statement, according
to which, incomplete correction with a weak myopic
defocusing prevents the eye from growing.1-3 However,
this approach appears to be contradictory to several
clinical studies which have shown that insufficient
correction of myopia increases eye growth more than
full correction does. 4- 6
EDITION ONE 2012
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diseases. In 1997, he was elected as an active member
(academician) of the Russian laser academy of sciences.
Since 1998, Professor Kornilovsky has been a member
of the doctorate dissertation board of FSA IRTC “Eye
Microsurgery”. Since 2001, he has been a member of
the editorial board of the Russian “Ophthalmology”
journal. In 2004, he was appointed as the Head of the
Center for laser eye microsurgery at the Central Clinical
hospital of the RF Ministry of railways. Since 2008,
Professor Kornilovsky has held the position of Professor
of the Ophthalmology Department and Consultant of
the Clinical Ophthalmology Department of the National
Medical Surgery Center named after N.I. Pirogov of the
Russian ministry of healthcare and social development.
Professor Kornilovsky has worked in ophthalmology for 37 years, 21 years of which he has dedicated to research and teaching activities. He has run
courses in eximer-laser surgery and gives regular
lectures at the Ophthalmology Department of the
Institute of Postgraduate Medical Education of the
National Medical Surgery Center. He is the author
of 298 scientific papers on various topics of ophthalmology, over 30 inventions, patents and innovation
proposals. Lately, his studies are focused on refractogenesis, accommodation, differential diagnosis of
optical aberrations of eyes, vision correction using
spectacles, contact lenses, laser and reconstructive
surgery in patients with ametropias and ophthalmic
pathologies.
The purpose of this summarized work is to justify the
pathogenic characteristics of full vision correction of myopia.
The following results are based on long-term clinical
observations of patients with varying degrees of myopia
with or without full correction. A large number of eyes
(3,040 eyes, 1,520 patients) have been analyzed, using
standard techniques of refractometry and contemporary
technology of aberrometry. The obtained data was
compared with visual axis and paraxial zones focusing
at peripheral regions of the retina. These investigations
were performed and the data analysed in the context of
the fundamental studies about the characters of focusing
7
and absorption of photons by eye tissues and structures,
development of the convergent and accommodative
reflexes, accommodative convergentive relationships,
hydro and hemodynamics of the eye. Also a number of
studies about clinical and experimental research by various
authors on the effect of light deprivation, peripheral and
central defocusing of light beams on the eye growth and
axial myopia were partially implemented.
relationships. All of these are not present in a "newborn" eye.
Normal postnatal eye development includes the
progression from hypermetropia to emmetropia, which
can provide some explanation for myopia’s development
and progression.
Analysis of these periods allowed us to identify
three major stages of human eye development refractogenesis:
It is well known that the retina of the eye is a part of
the brain that is peripherally situated. The retina, as a
strictly specific receiver of light photons, is exactly at
the center of regulation of eye growth,7 which for years
was unsuccessfully looked for in the brain. The analysis
of experimental studies have shown that the influence of
light depriving and defocusing factors appear only at the
early stages of postnatal development of the eye as an
optical system immediately after birth and do not cause
myopia in adult animals. This should be considered
when attempting to transfer experimental data to the
clinical practice in order to justify a particular approach
to the correction of myopia. The accommodationconvergence demands, however, are specific to the
human eye and cannot be reproduced in experimental
studies on animals. Also, the period of postnatal human
eye development is longer and ends between 18 and 21
years of age.
Light is a principle factor influencing postnatal
development of the eye as an optical system beginning in
the first days of life, and occurs before the development
of accommodation and accommodation-convergence
reflexes. This is accompanied by different development
rates of the eye at different time periods.
•Stage I: Light (early) - from birth to 1 year,
elongation by 3 mm (from 16 to 19 mm);
•Stage II: Light and accommodation (intermediate) at age 1 to 3 years - elongation by 1 mm over
2 years (from 19 to 20 mm);
•Stage III: Light, accommodation and convergence (late), from 3 to 18 (18-21) years, elongation by 4 mm (from 20 to 24 mm). 8
A newly proposed concept of refractogenesis,
includes some hereditary factors as drivers for eye
development.7-10 Thus, the biological mitogenic fields of
growth develop in embryonic tissues of the eye. Among
these fields, a specific role belongs to the retina, as
the strictly specific receiver of the light energy. Light
photons are presumed to stimulate or suppress those
complicated processes in the retina depending on their
nature and distribution.
According to Gurvich’s theory,12 mitogenetic factors target
the cell nucleus (a) during dividing of the chromosomes (X)
and subsequently the effect is transmitted to the adjacent
cells. Moreover, cells with more intensive metabolic
exchange have stronger mitogenic sensitivity. Mitogenetic
radiation falls into the range of the ultraviolet spectrum
from 190 to 330nm, it has low but sufficient intensity
to influence the processes of fission in the adjacent cell
structures.12-14
Examining children by subjective methods as refraction might be a
challenging task.
Three thousand forty eyes (1,520 patients) have been
analyzed. During the normal postnatal development of
the human eye, the following processes are highlighted:
morpho-functional differentiation of the neuroepithelium,
development of the fovea and foveola in the macula, visual
acuity gradual increase, development of the accommodative
reflex and binocular accommodative-convergence
8
As a result of the high level of photoreceptor metabolism,
the retina is the leading and most important mitogenetic
field. Only the retina produces the neuromediator dopamine
which increases the potential of the cells to divide and be
matabolitically active. That holds the potential for regulatory
effect in the formation of the posterior pole, the growth of
the eye and associated clinical refraction.7-10 The dopamine
production and the breakdown of melatonin, is directly
dependent on the intensity of the light. This is the basis for
the different melatonin quantity during the day and night,
and also for seasonal variations. This coincides with the
concept that the peripheral part of the retina determines
the primary growth of the posterior eye during the postnatal
period. The light entering the eye, depending on variables
such as pupil, accommodation, refraction and the degree
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of ametropia, causes the different patterns of background
illumination. This will lead to a variable distribution of the
photons of light on the receptors field of the retina, affecting
the mitogenic activity also. That is perhaps the main factor
which determines the primary growth of the posterior eye
during the postnatal period.7, 9-11
Through emmetropia and full vision correction of myopia,
the light rays are focused on the foveola which ensures
minimal aberration blur. This prevents the scattering of
light photons in the zones of parafovea and perifovea of the
macula. In conditions of illumination, the minimal scattering
of the light photons inside the eye contributes to the
formation of a strong accommodative reflex, which drives
the function of the accommodative system of the eye.
In precise focusing or full vision correction of myopia,
the rods of the peripheral regions of the retina are
minimally affected. This eliminates the stimulating
effect of light photons on the retina and potentially
reduces the number of free radicals which build up
during the photochemical reaction.
In myopia, due to focusing in front of the retina, the
dispersion of light inside the eye increases, circles of light
dispersion emerge across the macula, in the paramacular
and peripheral regions of the retina. With full correction
of myopia using spectacles or contact lenses, the circles
of light dispersion are reduced. In people with myopia,
the pupil in photopic and mesopic conditions is always
wider than that of emmetropics, which is associated
with accommodative disparity. It should be stressed
again that myopic defocusing of the light in front of retina
increases the light dispersion inside the eye, causing
exposure of the peripheral zones of the retina. This may
lead to predisposition of mitogenic background which
occurs only when its cells divide during the growth of the
organism. This appears to be a leading factor for primary
growth of the posterior eye .7, 9-11
In standard situations, like emmetropia or full vision
correction of myopia, there are minimal optical aberrations.
The accommodation reflex begins when the objects
are located at a distance less than 5 meters away and
reaches its maximum when the location of objects are
at a very close distance, dependent on many variables.
In cases with incomplete vision correction of myopia
there is a disturbance in the formation of accommodation
reflex which leads to it weakening. Furthermore, the
weakness of accommodation should be considered not
only as a factor in disturbing focus but also as one of the
causes of hydro-hemodynamic disturbances in the eye,
leading to the progression of myopia and the development
of complications. Therefore, one may assume that
performing partial correction of myopia, which weakens
the accommodation reflex, may be another mechanism
for eye elongation. These factors combined with any
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degree of under-correction of myopia and subsequent
defocusing of the light and optical aberrations might
be crucial for progression. This is true for all types of
ametropia and methods of their correction. The modern
approach considering aberrations as an objective measure
of the effectiveness of correction methods appears to
be promising. Furthermore, restoration of the optical
system, including correction of the Point Spread Function
(PSF) and the Modulation Transfer Function (MTF), would
correspond to emmetropic refraction of a healthy eye.15, 16
So when comparing spectacle and contact lens correction,
the benefits of vision with contact lenses were evaluated
on the basis of PSF and MTF, with special accent when
correcting severe ametropia. At the same time, these
studies allowed the power of the selection of contact lens
to be judged and to avoid the effects of hypo-correction
or over-correction. In addition, analysis of the degree of
mobility of the contact lens with an emphasis on the
assessment of light transfer function of the optical system
(eye & contact lens) allowed the optimal base curve to be
chosen and the best effect of the correction of aberration
could be achieved by improving of the optical transfer
function (Figure 1, a, b). In all cases without full vision
correction of myopia, due to residual aberrations, the optical
transfer function was affected which was clearly reflected
by PSF and MTF.16
In physiological optics, aberrations refer to any angular
deviation of the narrow parallel beam of light from the
point of ideal intersection with the retina in the center of
foveola as they pass through the entire optical system of
the eye. Optical aberrations of lower orders are associated
with the defocusing of light beams and increase as
ametropia increases, and higher-order aberrations are
caused by imperfections in the refractive structures of
the eye and imperfections of the transparency.
It is known that the absorption of photons of light by retinal
photoreceptors might be leading to peroxidation of lipids
in the membrane and the formation of free radicals, which
accumulate if not completely deactivated, causing damage
to the retina itself and other adjacent tissues of the eye.
Therefore, it is possible to hypothesize that optical aberrations
can create chronic oxidative stress, the dynamics of which
determine the damage to the intraocular structures. With an
increased level of aberrations due to poor focusing of the light
flow, the pathology can manifest after decades and depends
not only on the excess of peroxide radicals, but also on the
condition of hydro and hemodynamics of the eye which are
disturbed in axial myopia. The coordinated performance of
hydro and hemodynamic systems provides distribution and
activates the performance of the Intraocular Fluid (IOF) with a
high content of such a powerful antioxidant as ascorbic acid in
the anterior and posterior segments of the eye. Produced by
the secretory part of the ciliary body, the IOF contains 25-50
times the concentration of ascorbic acid than blood plasma.
9
a
b
c
d
e
f
Figure 1: Demonstration of aberrations dynamics after contact lens correction of myopia on the right (a) and left eye (b). PSF simulation before CLs
correction and with contact lens (c and d). The graphs e and f highlight MTF (red line) before full vision correction, and with full contact lens
correction of myopia. MTF curve for the eye with emmetropic refraction (green line). The limitations by light diffraction in the pupil (blue line)
are also demonstrated.
Intraocular Fluid provides nutrition to all transparent
structures of the eye (cornea, lens, vitreous body),
protecting them from the peroxide radicals. It is known
that the cornea does not pass short ultraviolet light
(C) which normally does not exist on earth because
it is absorbed by the ozone layer of the atmosphere.
Oxidative radicals could be formed in the cornea when
the ultraviolet light of intermediate length (B) passes
through it. The lens blocks the high-energy ultraviolet
light including most of the longer spectrum (A) protecting
the vitreous body and the retina from them. During the
circulation of IOF, peroxide radicals in all tissue structures
of the eye, above all in the retina, become deactivated. It
is worth noting that during the day up to 200 ml of IOF
circulates through the vitreous body.
From this perspective, it is sensible to assume that the
functional purpose of cisterns and canals of the vitreous
body are to connect retro crystalline space with the
premacular bursa. It is our opinion that this is exactly what
provides a rapid movement of IOF and active participation
of glutathione of the lens in the restoration of inactivated
by radicals ascorbic acid.
Retinal “dialysis” of the IOF is carried out through an
oncotic pressure gradient which is created by the blood
proteins circulating in the choroid. Due to this gradient,
IOF actively diffuses from the vitreous body through all
10
layers of the retina to the choroid, rendering peroxide
radicals that were formed in retina during photochemical
reaction inactive.
The intensity of IOF circulation may be linked to the
activity of the accommodative apparatus of the eye. The
status of the latter depends on the functioning of the entire
irido-cyclo-lenticular complex (ICLC).17 Therefore, again we
can hypothesize that in partial correction of myopia ICLC
works worse than in complete correction, as activation of
IOF flow through the venous sinus in turn stimulates blood
flow and venous hemodynamics in the eye, as a whole.
All of the information above provides the eye care
practitioner with ideas that lens accommodation not
only functions to focus the light throughout optical
structures, but also has an important role in hydro and
hemodynamics in the anterior and posterior eye.15, 17
In myopia, especially in the case of incomplete full
vision correction, the accommodation is weak. However,
the dispersed illumination of the retina is wider and
therefore might be responsible for the production
of more peroxide radicals. So, it may result in the
development of pathological processes in the tissues
of the eye (vitreous humor, retina, lens, trabecular
apparatus of the anterior chamber angle, cornea) during
the axial elongation of the eye.
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Partial correction of myopia might have the
following unwanted consequences:
•Weaker accommodation reflex and general weakness
of the ciliary muscle with all possible scenarios;
•Excessive optical aberrations within the eye which
affect the normal function of the central, paracentral
and peripheral regions of the retina;
•Excessive dispersion of light on the receptor’s field
at the peripheral regions of the retina, which might
stimulate the mitogenetic field and growth of the
posterior segment of the eye.
•Activation of the photoreceptor’s membrane lipid
peroxidation, leading to chronic peroxide stress and
enhancing the damaging effect of visible light on
the intraocular structures.
and functioning of accommodation reflex and
optimizes the relationships between accommodation
and accommodation-convergence ratios.
3. In cases of full vision correction of myopia, light
distribution on the peripheral receptor’s fields is
more precisely related to the day-night variations.
Therefore, the formation of the neurotransmitter
dopamine in it and the breakdown of melatonin is
close to the natural rhythm.
4. Full vision correction of myopia is an attempt to minimize
the optical aberrations associated with defocusing,
formation of a stronger accommodation reflex and less
stimulation for eye growth and all related consequences
recognized as pathological changes in myopia.
References
Published literature states that the accommodation
convergence loads lead to the development of school
age myopia and are believed to be important external
environmental factors affecting the final formation
of clinical refraction of the eye.18 In 2003, Czepita
came to the conclusion that light and darkness play
an important role in the pathogenesis of refractive
abnormalities based on an analysis of the literature on
modeling of experimental myopia and clinical studies of
shortsightedness.19 In her opinion, the development of
myopia and hyperopia can be associated with sleeping
in a lighted room and disturbance of the daily rhythm
of illumination. However, as the author notes, it is not
clear by what mechanism the light energy affects the
growth of the eye and the formation of particular types
of refractive errors.
Based also on this paper, the pathogenetic justification
of the complete correction of myopia, allows one to
understand why light is a factor for eye growth at all
stages of postnatal development. Therefore the different
patterns of light focusing in complete and partial
correction of myopia, may influence the progression of
myopia and the development of its complications.
Considering the aforementioned discussion, the
Eye Care Practitioner should aim to achieve full vision
correction, considering near hypo-correction only in
special cases and presbyopia.
Conclusions
1.The optical correction of myopia should be
considered from the standpoint of achieving the
precise focusing of light in the foveola in order to
optimize not only vision, but also the light energy
load on surrounding parts of the retina.
2. Full vision correction of myopia facilitates minimal
dispersion of light inside the eye, better formation
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1. Tarutta E.P., Khodzhabekian N.V., Filinova O.B., Kruzhkova G.V. Impact
of continuous slight myopic defocus on the postnatal refractogenesis//
Ophthalmic Res. – 2008, - No.6. – Vol.124. – p. 21-24.
2. Filinova O.B. Dynamics of refraction and muscule balance of
children in the setting of continuous slight myopic defocus
in the alternating binocular and monocular formats // Russian
Pediatric Ophthalmology.-2009.- No.1.- p.31-33
3. Tarutta E., Khodzhabekian N.V., Filinova O.B., Kruzhkova G.V.
Impact of continuous myopic defocus on the refractogenesis
and myopia progression // Ophthalmic Res., abstract of EVER
2008, p.70.
4. Chung K, Mohidin N, O’Leary DJ Undercorrection of myopia
enhances rather than inhibits myopia progression // Vis Res
2002; 42(22):2555-2559.
5. Hung G.K., Ciuffreda K.J. Effect of Undercorrection on Myopic
Progression // Invest Ophthalmol Vis Sci 2003;44: E-Abstract 4791.
6. Adler D, Millodot M. The possible effect of undercorrection
on myopic progression in children. Clin Exp Optom. 2006
Sep;89(5):315-21.
7. Kornilovskiy I.M. A new theory of refractogenesis //
Ophthalmology, 2004., Vol.1, No.1.- p.6-14.
8. Kornilovskiy I.M. Patogenetic role of the light factor at different
stages of postnatal refractogenesis // X All-Russian research
and training conference with an international participation
“Fedorov reading” – 2012, Moscow.2012.- p.66-67.
9. Kornilovskiy I.M. A new theory of eye development
and formation of its clinical refraction. VIII congress of
ophthalmologists in Russia. Moscow.2005 p.255.
10.Kornilovskiy I.M. The role of light factor in refractogenesis //
Medical Journal Siberian medical review 2006.-2(39).- p.70-73.
11.Kornilovskiy I.M. A new three-factor theory of refractogenesis //
Book of abstracts of the jubilee conference “Refraction 2008” –
Samara, 2008.- p.51-53.
12.Gurvich A.G. A biological field theory // Moscow, 1944.-156 p.
13.Gurvich A.G., Gurvich L.D. Introduction into mitogenesis.
Moscow: 1947.-155 p.
14.Gurvich A.G. Selectas (Theoretical and experimental research)
// Moscow, “Medicine”, 1977.-162 p.
15.Kornilovskiy I.M. Pathogenetic directionality of different methods of
correction of aberrations of the eye's optical system. // Refractive
surgery and ophthalmology, 2010. vol.10., No.2. - p. 21-27.
16.Kornilovskiy I.M., Kuptsova O.N. Evaluation of the efficiency of
contact correction while restoring the optical refractional system of
the myopic eye // Modern optometry, 2011, No.3-p.18-21.
17.Kornilovskiy I.M. The peculiarities of biomechanics of the
iridocyclolens diaphragm and its role in the development
of ophthalmopathology // Materials of a workshop in
biomechanics, Moscow, 2002. p.9-13.
18.Avetisov E.S. Myopia // Moscow, ”Medicine”, 1986. – 239 p.
19.Czepita D. The role of light in pathogenesis of refractive error
development. Bull Math Biol., 2002; 104 (1):63-65.
11
Full Refractive Error Correction- The Past,
the Present and the Future.
Marek Habela
Introduction
Since the WHO (World Health Organization) defined
“health” as the state of full physical, mental and social
well-being, not only as the absence of diseases or
health impairments, many tools to evaluate quality
of life have been created.1 The development of these
instruments has enabled the creation of a different
approach to establishing standards of vision quality and
for example, has changed the implementation of some
ophthalmic surgical procedures (cataract extraction in
the fellow eye, cataract extraction in patients with age
related macular degeneration - AMD).
There are plenty of factors influencing quality of
vision: visual acuity, amplitude of accommodation,
contrast sensitivity, color vision, stereoscopic vision
and sensitivity to glares and halos. Among all of
them, visual acuity seems to be the most crucial and
more widely used. The patient should achieve the
best corrected visual acuity by implementation of
appropriate examination techniques. Undercorrection
may lead to unfavorable changes in everyday life: poor
progression in studies and work, changes in behavior,
physical appearance and facial expressions.
This article will debate the full vision correction
concept, presenting the beliefs and the trends that
were followed in the past, the current situation and
behavior and the future perspective of it. It will
firstly present a brief epidemiology of the refractive
errors and modes of correction, along with the past
knowledge and approaches, but will also touch on
modern thinking and the future management of vision
correction.
Epidemiology of refractive errors.
In most cases children are born with approximately
3.00D of hyperopia. As the child grows up, the axial
length of the eye globe elongates concurrently with
the decrease of the refractive power of the cornea and
lens. 2 This phenomenon is called emmetropization and
leads, in most cases, to the result that the child at the
age of 6 years old becomes slightly hyperopic (0.50 to
1.50D) or emmetropic.
12
Dr. Marek Habela MD
Dr Habela was born
in 1951 in Nowy Sącz,
Poland. In 1975 he
graduated with honors
from the Military Medical
University in Łódź.
From 1977 to 1998,
he initially served as a
Assistant Professor and
afterwards as the Head
of the Ophthalmology
Department
at
the
Polish Air Force Institute of Aviation Medicine. He
is both an Ophthalmology and Aviation Medicine
specialist. In 1982 he was awarded a PhD degree
for his doctoral thesis on “Soft contact lenses use
in refractive errors correction”. He has also been in
private ophthalmic practice since 1978, specializing
in contact lenses and an active IACLE member.
In school age, progression of myopia may be
observed. In the United States myopia was found in
3% of children, aged 5-7 years old, in the examined
population. At 10 years old this number increases to
10% and in 17 year olds it rises to 25% of the evaluated
sample. These outcomes significantly differ from
particular ethnic groups, for example in Taiwan myopia
occurs in 84% of teenagers at the ages of 16-18 years
old. 3 Myopia progression, which occurs during school
age (“teen” myopia) is approximately 0.50D per year
and stabilizes at the age of 16-18 years old. Myopia
can also occur in adult emmetropes and is commonly
related to intensive work at close distances.
Hyperopia correction is clinically underestimated.
This refractive error occurs in 6% of children at the
age of 5 -15 years old, and its level does not change as
significantly as in cases of myopia. Some children with
non-detected and uncorrected hyperopia experience
and report difficulties when they work at close
distances, which subsequently leads them to poor
performance at school. This problem may increase
when the amplitude of accommodation decreases and
the patient with hidden hyperopia will usually choose
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activities not requiring long-lasting, precise tasks at
close distances. Hyperopic patients with strabismus
or amblyopia are most frequently corrected.
Refractive error correction.
The views regarding refractive error correction have
been changing over time. Myopia was supposed to be
a visual impairment that seriously decreased quality
of life and was therefore corrected by various means.
Myopia control was often the primary target, therefore
the emphasis was placed on means of control and
not on quality of vision. Regardless of the numerous
variations, the golden principle is to achieve the best
corrected visual acuity with the lowest power of minus
lenses, or with the highest power of plus lenses.
The inheritance from the past
Some years ago there were other “compulsory”
rules in refractive error correction, applied especially to
children:
•Do not correct refractive errors in children who do
not report any problems.
•Do not correct myopia at less than -1.50D.
•In myopia correction, prescribe 0.50 – 0.75D less
power than required.
•Myopic children should work at close distances without correction.
The principles described above were based on
the belief that myopia progression is evoked by
accommodative spasm. It was also believed that myopia
at less than -1.50D should not be corrected because
children focus on the items localized at close distances
and this refractive error does not impair the vision at
the object of interest. Elimination of accommodation
as the main cause of myopia progression was the
basis of undercorrection and the recommendation to
work at close distances without correction, or even to
use bifocal or multifocal spectacles. Accommodation
was manipulated in several studies using atropine eye
drops for years, without paying attention to discomfort
and visual disturbances in treated patients. Another
pharmacological method of treatment was the use
of anti-glaucoma drops to prevent action in the eye
globe from centrifugal forces and its elongation in axial
length. Taking into consideration that in those days the
only local anti-glaucoma medication was pilocarpine,
one can clearly understand the disadvantages of this
method.
Flat fitting of rigid, gas permeable contact lenses was
also a popular method of myopia control some years
ago. 5,6,7
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Current understanding
In light of modern knowledge, none of the methods
described above may effectively control myopia
progression. 8 Furthermore, the studies outcomes
suggest faster myopia progression in undercorrected
children. 9 Genetic factors may also have great impact
on refractive error phenotype and development.10
Patients should achieve the best corrected visual
acuity by appropriate examination techniques, be
encouraged to physical activity outdoors and to
comply with visual work hygiene rules.
Experiments on animal models suggest that
the peripheral retina has the greatest impact on
emmetropization and myopia progression. Further
studies are required to effectively impede refractive
error progression.11,12
On the basis of these reports, the studies on
orthokeratology and its effect on myopia progression
have been conducted.13 There are studies still in
progress and nowadays it is difficult to unequivocally
determine if this method will gain popularity and
become convenient and effective for myopia control.
Patients follow-up
The management of patients with a refractive
error depends on the error type and the age of the
patient. The first visit should be the introduction of
long-lasting eye care. At the beginning, visits should
be relatively often, every 2- 6 months depending
on the refractive error and its progression. After
proper, well justified correction, the patient should
appear every year for follow-up visits or earlier
when required (subjective complaint of decreased
vision for example). Contact lens wearers should be
examined every 6 months.
Proper communication with the patient is still crucial
and sometimes problematic. The false perceptions
and beliefs, that have been repeated for years, that
myopia would let the eye “work”, are still convincing
for many patients. A suitable approach is a motivating,
rational explanation in an easy and understandable
way in order to elucidate the cause of the refractive
error and the available methods for its correction.
The argument that convinces many patients is the
fact that more than 80% of the knowledge humans
gain about the world is through the visual system.
Visual acuity and quality of vision have great influence
on intellectual development, learning processes,
professional work and general state of health. A good
method is to present the patients with the quality of
vision they get with and without correction.
13
Management of hyperopic patients
Management of myopic patients
Children are far more difficult to manage than
adults. Parents turn up for an ophthalmological
consultation with their children most often alarmed
by convergent strabismus. Children at preschool age
very rarely complain about poor vision, mainly due
to undemanding visual requirements and a broad
amplitude of accommodation which can compensate
even high hyperopia. Due to immaturity of the brain,
children are prone to unfavourable adaptive changes
like suppression, amblyopia, eccentric fixation and
anomalous retinal correspondence.
In the majority of cases, myopia occurs during
school age and stabilizes approximately at 16 -18
years old. Blurred vision develops slowly, usually
unnoticed by the child until the myopia reaches
- 0.75 / -1.00D. Children and young adults require full
spherical or sphero -cylindrical prescriptions in the
form of glasses or contact lenses. Myopia usually
becomes stable at the end of the second decade
in life, but due to intensive visual work, some
patients experience myopia progression even in
their 3rd decade, especially during intensive work
at close distances. In adults with presbyopia (or
just before presbyopia) refractive error is usually
relatively stable. However, depending on lifestyle,
near modification is required sooner or later. In a
small percentage, myopia decreases in conjunction
with crystalline lens hardening.
The examination requires temporary paralysis of
accommodation to estimate the level of refractive
error so proper correction can be made and measures
taken to prevent amblyopia and /or accommodative
strabismus. Proper correction should relax the
accommodation and facilitate orthophoria including
close distances, with the best visual acuity for all
activities. 4 Contact lenses are an excellent alternative
to spectacles, but with some limitations. Contact
lenses are an invaluable option in high hyperopia or
anisometropia correction.
Adaptive optics as future options
for correction
The original purpose of adaptive optics was to
eliminate distortions caused by rays passing through
the atmosphere during astronomical observations. The
existing method consists of steering the telescope
by computer and distorting the telescope mirror
in a manner to correct the errors in the acquired
image (distortions are in the order magnitude of
micrometers).
Nowadays we are able to measure the optics of the
human eye with great precision. Since the first trials
of Smirnov 14 in 1961 on wave front of the eye, studies
conducted by scientists have led to the creation of
special measurement devices, an example being
aberrometers. A milestone in clinical usage of these
devices was the connection of the Shack-Hartmann
sensor with a camera by Liang in 1994.15
Some children do not report any complaints and do
not have any symptoms despite uncorrected refractive
error. With time however, decreasing amplitude of
accommodation would lead to complaints, the most
prominent of which is discomfort.
Long -term visual work in patients with low
level hyperopia may exhibit signs suggesting
other diseases such as migraine, sinusitis and
neurological disorders. Diligent examination reveals
existing refractive error and the establishment
of proper correction eliminates discomfort. In
presbyopic patients, progressive spectacles might
be recommended to enable comfortable work at all
distances (for example “office” glasses).
14
Visual acuity is impaired by High Order Aberrations
( HOA ), so elimination of HOA may significantly
improve vision.16 Correction may be made at the
source of aberrations ( spectacles, contact lenses,
intraocular implants ) but also at eye structures
(tear film, cornea, aqueous humour, cr ystalline
lens and vitreous body ). The adaptive optics
principles enable HOA elimination through custom
made contact lenses or intraocular implants with
modified anterior surfaces or can be custom made
on the basis of aberration mapping before or
during refractive surgery procedures. Custom made
correction significantly improves visual acuity and
has great impact on vision especially in low contrast
conditions.
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Will further technological developments allow
us to achieve “super vision”? It depends on the
technological advances and their implementation by
the industry. Contact lenses and intraocular implants
manufacturers should be ready for the huge leap
in quality, when currently used autorefractometers
will soon be replaced by aberrometers to estimate
refractive errors. The biggest problem is the fact
that the eye is not a static and stable optical
construction. The changes in aberration take place
during accommodative attempts, pupil size and
ocular surface dynamics. They are dependent on
many variables such as time of day, physical and
mental condition, patient age, etc. “Super vision”
now seems to be an illusion, but further studies and
technological progression may enable this illusion
to become a reality. 6 Perfectly fitted contact lenses
precisely eliminating high order aberrations may set
visual acuity of 2.0 as a new standard.
12.Zadnik K, Mutti DO. How applicable are animal myopia models
to human juvenile onset myopia? Vis Res. 1995;35:1283-1288
13.Wilcox, Peter E. ; Bartels, David P. . Orthokeratology for
Controlling Myopia: Clinical Experiences. Contact Lens
Spectrum . 2010;5:39-42
14.Smirnov MS. Measurment of the wave aberration of the human
eye. Biophys J.1962;7:766-795
15.Liang J.; Williams DR.; Miller DT. Supernormal vision and high
resolution retinal imaging through adaptive optics. J Opt Soc
Am.1997;14:2884-2892
16.Porter, Jason et al. Adaptive optics in vision science. Hoboken,
NJ Wiley Interscience, 2006
Till then, we all need to see our patients as the
person who deserves to get the best care from
us as clinicians. Full vision correction along with
optimal eye care in general should be at the top of
our list. Nowadays, diagnosis and management of
refractive errors has improved a lot, due to advances
in technology and research. It is in our hands and
becomes our duty as Eye Care Professionals to keep
ourselves updated with these advances in modern
research and technology and by combining these
with our clinical experience, to offer our patients the
vision and the visual quality that would benefit them
most.
References
1. Elliot, David B.; Pesudovs, Konrad; Mallinson Trudy. Visionrelated quality of life. Optom Vis Sci. 2007;84(8):656-658
2. Blum, H.L.; Peters, H.B.; Bettman, J.W. Vision screening for
elementary schools: The Orinda Study. Berkeley: University of
California Press. 1959
3. Lin LL; Shih YF; Tsai CB, et al. Epidemiologic study of ocular
refraction among schoolchildren in Taiwan in 1995. Optom Vis
Sci. 1999;76:275-281
4. Grosvenor, T.; Primary care optometry. Elsevier Inc., 2007
5. Grosvenor, T.; Perrigin, D.; Perrigin, J.; Quintero S. Do gaspermeable contact lenses control the progression of myopia?
Cont. Lens Spectrum. 1991;6:29-35
6. Stone, J. Contact lens wear in the young myope. Brit. J.
Physiol. Opt. 1973;28:90-134
7. Stone, J. Possible influence of contact lenses on myopia. Brit.
J. Physiol. Opt. 1976;31:89-114
8. Ong ,Editha et al. Effects of spectacle intervention on the
progression of myopia in children. Optom Vis Sci. 1999;76:363-369
9. O’Leary, Daniel et al. Undercorrection causes more
rapid progression of myopia in children. Optom Vis Sci.
2000;77(12):24
10.Goss, David A.; Jackson, Tonya W. Clinical findings before the
onset of myopia in youth:4.Parental history of myopia. Optom
Vis Sci. 1996;73(4):279-282
11.Smith et al. Peripheral vision can influence eye growth and
refractive development in infant monkeys. Invest Ophthalmol
Vis Sci. 2005;46:3965-72
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15
Top 10 Questions on
Full Vision Correction
Answered by Eye Care Professionals
1
What does Full Vision
Correction mean to you as an
Eye Care Professional today?
Dr. Tatyana Poznyakova • Moscow, Russia
When discussing optimal vision correction, we
increasingly implement the methodology of total
(full) vision correction. When performing subjective
refraction it is necessary to achieve visual acuity at
the low border of 1.0 in order to provide satisfactory
vision. Optimal spherical correction should be based
on the principle of “minimum minus, maximum
plus”, along with a precise and total correction
of astigmatism. All these steps provide a sharply
defined focus on the retina and good accommodation.
The proper interaction of accommodation and
convergence promotes muscular balance and
eliminates the asthenopic complaints. All the above
are essential for children and adolescents. Optimal
vision correction of different refractive errors, such
as myopia, hypermetropia and astigmatism, from an
early age promotes high visual acuity, prevents the
development of asthenopia, amblyopia and squint and
it seems to slows down myopia progression. In each
specific case we should take adequate strategic steps,
bearing in mind the history of previous correction,
individual characteristics of accommodation and
muscular balance ultimately applying step-by-step
correction followed by some adjustments, if needed.
Our aim is to normalize accommodation and muscular
balance and to achieve optimal correction for sharp
vision. This will facilitate our patients with visual
comfort and improve their quality of life.
2
What does Full Vision
Correction mean today for
a patient?
Dr. Elena Shcherbakova • Rostov-on-Don, Russia
Nowadays, busy lifestyles require perfect vision for
everybody. People of all ages are active motorists,
spend a lot of time in front of their computers and
participate in sports activities. It means that the
eye and the optic system have high demands and
16
need clear focus, which is possible only with full
vision correction. Kids and teens actively perceive
the world. They are very creative, innovative and
mobile and that means full vision correction of their
ametropia at a young age is part of their harmonious
evolution not only for their visual system, but for
their personality as well.
As a pediatric ophthalmologist I observe a striking
change in kids and teens’ behavior when they
have full vision correction versus children with
undercorrection. Young people are more sociable
and active, and they are more interested in
additional activities and adapt easily to different
environments. Young painters, for example, are
happy if they could see every detail and better
interact with other people. Young musicians could
better see the faces of the audience and their
performance improves.
For adults, full vision correction means better
quality of life, lack of asthenopic symptoms and a
higher degree of safety on the roads as both drivers
and pedestrians. I always try to explain to all my
patients the benefits they will have from full vision
correction.
3
Does full vision correction
depend on the age of the
patient?
Dr. Maria Rydz • Olsztyn, Poland
Full vision correction does not depend on the age
of the patient! Several studies provide evidence that
full correction of refractive error in children guarantee
the proper development of their vision. There are
many studies proving that precise correction may
slow or control myopia progression. It also concerns
adults. However, in this case emetropia progression
may be less evident when correction is insufficient.
Uncorrected or under corrected hyperopia for
example, can cause headaches, astenopia, decreased
vision efficiency and signs of chronic conjunctivitis
in all patients which may lead to fixed impairment
of the visual system function in younger patients.
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There are also many studies looking at behavioral
changes as a result of decreased or uncorrected
vision. Several of those studies have shown that full
correction of refractive error improves vision specific
quality of life in older adults, provides independence
and possibility of community participation. Therefore
full vision correction is a substantial component for
good quality of vision and life for patients at any age.
4
Does full vision
correction depend on
patient’s refraction?
Dr. Arleta Waszczykowska • Łódź ,
Poland
Vision is a dynamic and complicated process.
The appropriate optical correction is based first on
a detailed medical history, a subjective refraction
and all information on previous optical correction
and progression of the condition. Contemporary
medical knowledge however, does not define the
normal ranges of clinical refraction in patients of
different ages. Additionally, visual acuity is variable
during the patients’ life.
Refractive correction, with the aim to achieve
the desired visual acuity, does not always provide
satisfaction for patients. There are very demanding
patients who expect their visual acuity to be even
better than 1.0 and on the other hand there are
patients who do not tolerate full vision correction.
Therefore, every single patient requires an individual
approach with solicitude for comfort of vision at
every distance.
Sometimes there are medical considerations
for sub-maximum correction of visual error. For
example, in hyperopic young children. The aim
of this approach is to set stimulus to terminate
the process of emmetropization (up to 4 years of
age) or in significant anisometropia that can cause
anisoeiconia interfering with fusion and stereoscopic
vision. Sometimes, in cases of accommodative
strabismus, the specialist may use hypercorrection
as a treatment modality.
Optical correction greatly depends on individual
acceptance of the prescribed correction. Very often
full correction of high power irregular astigmatism
will be poorly tolerated with spectacles and comfort
may be achieved only while wearing contact lenses.
In spite of the vast knowledge about up-to-date
recommendations of refractive error correction
based on clinical studies, the specialists are very
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often facing great challenges. To summarize, full
refractive error correction essentially depends on
refraction, but there are many other factors that
play a crucial role in the final decision.
5
Does full vision correction
depend on the patients’ needs,
life and activities?
Dr. Pavel Rezek • Kolín, Czech Republic
Firstly I would ask, what full vision correction
really means… It is important to know what the
overall ability of the eye is to reach full vision, or
as the highest possible visual acuity. This is very
important information for the clinician on each
individual case, in the context of our standards for
”normal” visual acuity. Although in refraction the
goal may be different, where the examination’s
target should not always be the best achievable
visual acuity. Sometimes a patient might be hypocorrected because this type of correction is more
comfortable for them.
There are however situations where full vision
correction is really needed! First of all, in hyperopic
children, as a method of strabismus treatment
where full correction is a must, especially at
preschool age. Another issue that has created many
discussions lately, is the magnitude of correction
in myopic children and the effect of full vision
correction in emmetropisation. Although there are
several well designed studies, more work is needed
in order to provide conclusive results.
Another group of patients that are often overlooked
is the group of hyperopic patients with angle
closure glaucoma, where full vision correction is
needed to uncover the”hidden” part of hyperopia,
relaxing the accommodation in order to decrease
the intraocular pressure.
Then we have some ”special” groups of
patients. These include patients who have special
requirements related to their careers such as
drivers, pilots, officers, etc. There are also different
needs for athletes in ice-hockey, baseball and
tennis for example where dynamic visual acuity
is crucial and different for runners, swimmers,
climbers, scuba divers, etc. These examples
demonstrate that it is not easy to state that full
vision correction should be a general rule. Also, it
cannot always be accepted by the patient. First of
all, we need to discuss this with our patients and
acquire more knowledge about the specifics of
their occupation, their life style, their needs and
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wishes and subsequently to work together in order
to achieve their expectations. So, yes, full vision
correction depends on the patients’ needs, life
style, activities and on many other medical or nonmedical variables.
6
As Eye Care Professionals, do
we have all the technological
advances/instruments we
need to achieve full vision
correction?
Dr. Hrvoje Raguz • Zagreb, Croatia
In my opinion the ability to discuss this question
depends on the definition of full vision correction.
For example, technical or theoretical versus
the real possible capacity of the eye and visual
system in question. Keeping in mind the refractive
errors together including spherical and chromatic
aberration and high order aberrations, we have
devices that enable us to measure them. But,
there is always a question of individual perception.
For example, whether the theoretical/calculated
correction really improves the patients’ vision
or not. Subjective perception of surroundings
varies from patient to patient, so we cannot
just implement the results from "the machinery"
directly. There is still a place for good old subjective
exams and the patients’ decision. With regards
to the new approach to myopia progression (that
peripheral visual "inaccuracy" might be the cause
of progression), it might be useful to give younger
patients the most accurate (or calculated) correction
in order to “stop” myopia progression, as they are
usually more adaptable to correction changes. With
all of the advancements in knowledge and devices
in our days, we are definitely able to reach the
optimal correction for each patient.
7
What is the difference between
“perfect vision” and full vision
correction?
Mr. Edoardo Marani • Modena, Italy
My opinion is that we must consider, first of
all, the difference in meaning between “perfect
vision” and “full vision correction”. So, assuming
that we can probably achieve a “perfect vision”
by a “perfect compensation” of a refractive error
(but we know that’s not true) this doesn’t mean
that the quality of vision and the quality of life
are guaranteed. Of course, visual acuity is a
strong key factor. According to some authors
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(Christine Knauer et al. “The Value of Vision”Graefe’s Archive for Clinical and Experimental
Ophthalmology Incorporating German Journal of
Ophthalmology – 2007), it seems that patients with
a visual acuity between 0.7 and 0.5 would be ready
to cede 19% of the years of their lives to return to
a normalized vision.
Anyway, we have to take a look beyond and
pay attention to the importance of “full vision”
remembering that, as well as in other fields of
science, the gold standard of each treatment is
to improve quality of life. For the patients (and it
should be the same for Eye Care Professionals)
quality of life is strictly related to quality of vision.
This is true for all of us at any age or condition and
includes a large number of variables.
The approach to compensate a refractive error is
consequently a crucial factor and it’s well known that
contact lenses are probably the best method we have
to improve quality of vision. So the question is: “Are
we actually able to help our patients through the use
of contact lenses to improve their quality of vision
and consequently, the quality of their life”? I think
that unlike a few years ago, modern technologies
(soft toric, multifocals, silicone-hydrogel, disposable
contact lenses) are able to support us in this
direction, because now, we improve not only the
quality of vision, but other important needs while
also guaranteeing the patient’s health.
8
How do we communicate
to our patients the concept
and the need for full vision
correction?
Dr. René Mély • Valmont, France
The major problem is that many patients think
that wearing a full correction, such as spectacles
or contact lenses, makes their eyes dependent
on it and weakens them. Many commercials on
the internet and in magazines claim that you can
cure your ametropia with exercises and it is very
important to dispel this myth. The need for full
optical correction is particularly important in young
children under the age of 5 years old. Uncorrected
ametropia and especially astigmatism is a frequent
cause of refractive amblyopia which may result,
if not properly treated, in permanent vision loss.
To explain the concept of amblyopia, I tell parents
of the patients that the brain of the child will
“turn off” the blurry image of the uncorrected
eye which consequently doesn’t learn how to
see. Accommodative esotropia can in most cases
A magazine from Johnson & Johnson Vision Care
be efficiently treated by a full and consistent
correction of the associated hyperopia, especially
with contact lenses. In children above the age of 8
years old, myopia is the major concern. I explain to
the parents that recent scientific research has now
proven that under-correction produces an increase
in myopia progression. In adults uncorrected or
under-corrected ametropia, including presbyopia, is
a frequent source of asthenopia and this has a major
impact on quality of life.
Many patients do not wear their glasses for sports
activities and I tell them that good vision with contact
lenses may tremendously improve their results.
In the near future, customized wavefront-guided
lenses will probably become more popular in
terms of better full vision correction. In refractive
surger y,
with
wavefront- guided
methods,
extremely precise, individualized vision correction
outcomes might be achieved that would not
be possible with traditional refractive surgery,
contact lenses or spectacles.
In summary, we can plan for full vision correction
for our patients, after determining the best
customized option to improve their vision-specific
quality of life.
10
9
How can we get to the full
vision correction for our
patients by using spectacles,
contact lenses or refractive
surgery?
What are the elements
of success in full vision
correction with contact
lenses?
Dr. Ashraf Al Sayed Gamal Eldin • Riyadh,
Kingdom of Saudi Arabia
Dr. Koray Gumus • Kayseri, Turkey
Uncorrected refractive error, which is the most
common cause of vision impairment in the world,
has an important impact on quality of life and
the economic development of nations. So, the
correction of refractive errors is of great importance.
Recent studies confirmed the necessity and
importance of full vision correction to provide
better visual function and quality of life. Moreover,
it has been well documented that "under-correction"
was clearly causing more myopia. Hopefully, recent
groundbreaking new technological improvements
will
provide better modalities for full vision
correction.
Corrective options for full vision correction
vary greatly, depending on individual factors
such as personal preference, occupation and
age. Progressive multifocal lenses, which can be
identified as one of the most promising evolutions
in lens technology, are widely used in the most
advanced eyeglasses.
Newly designed contact lenses are promising for
full vision correction. In addition to their increased
ocular comfort level, they offer better visual quality
and superior contrast sensitivity. They do not only
correct spherical and cylindrical errors but also
improve optical quality by various technological
modifications. Multifocal soft contact lenses
can be used in middle-aged or older patients
for comprehensive vision correction at different
distances.
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There are several factors or elements which
are crucial in full vision correction. The first step
is to conduct proper refraction in dry and wet
(cycloplegic) stages. When it comes to refraction
itself, a complete spherical as well as cylindrical
refraction should be conducted with the Jackson
Cross Cylinder to validate the axis and the power
of the astigmatism.
Full vision correction should include the complete
prescription and that complete prescription
should be given in contact lenses without any
compromises, even in mild astigmatic cases.
Full vision correction means vision which has
1.0 vision in normal and low contrast conditions.
When it comes to contact lenses there should be
a proper evaluation of the pre - contact lens tear
film in order that the full vision correction given
to the patient will be stable vision all the time and
there is no drop of vision that might happen due
to tear film layer deterioration over the contact
lens.
Furthermore, full vision correction can be
achieved with contact lenses that are free from
any deposits and in that case shorter modalities
are recommended, such as one day contact lenses.
Let us not forget that contact lenses delivers the
extra benefit of full vision correction not only in
central vision but also in peripheral vision due to its
wider field of view when compared to spectacles.
There is more and more scientific evidence clearly
showing the importance of peripheral vision in the
control of myopic progression.
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