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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 Eye Eye Health Health Advisor Advisor 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 A magazine from Johnson & Johnson Vision Care 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 Eye Eye Health Health Advisor Advisor 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. A magazine from Johnson & Johnson Vision Care 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 Eye Eye Health Health Advisor Advisor 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 A magazine from Johnson & Johnson Vision Care 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 EDITION ONE 2012 Eye Eye Health Health Advisor Advisor 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. A magazine from Johnson & Johnson Vision Care 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 EDITION ONE 2012 Eye Eye Health Health Advisor Advisor 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 A magazine from Johnson & Johnson Vision Care 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 EDITION ONE 2012 Eye Eye Health Health Advisor Advisor 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. A magazine from Johnson & Johnson Vision Care 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 EDITION ONE 2012 Eye Eye Health Health Advisor Advisor 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. A magazine from Johnson & Johnson Vision Care 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 EDITION ONE 2012 Eye Eye Health Health Advisor Advisor 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 17 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 18 (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. EDITION ONE 2012 Eye Eye Health Health Advisor Advisor 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. 19 ACUVUE® and Eye Health Advisor ® are trademarks of (insert legal entity). Johnson & Johnson Vision Care is part of (insert legal entity). (c) (insert legal entity) 2012.