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MYOPIA
MYOPIA : PROGRAM
Myopia: program I
• Generalities
– Definition
– Etiology
– Epidemiology
• Classification:
– According to magnitude
– Clinical
Myopia: program II
• Myopia simple:
– Characteristics
– Clinical exam
– Prescription criteria. Factors:
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Age
Anisometropia
Binocularity
Control of myopic progression
Myopia: program III
• Degenerative myopia:
– Characteristics
– Clinical examen
– Prescription criteria. Factors:
• Type of optical compensation
• Pseudomyopia:
– Characteristics
– Clinical exam
– Prescription criteria
Myopia: program IV
• Nocturnal myopia:
– Characteristics
– Treatment
MYOPIA: GENERALITIES
Myopia: Generalities I
• Refractive condition in which the image of
an object at a distance does not form on
the retina but focuses in front of the
retina.
• Structural causes of myopia could be:
– Excessive axial longitude of the eye
– Excessive power of the eye
– Error in the relationship between axial
longitude and power
Myopia: Generalities II
• The etiology of myopia depends on diverse
factors. Such as:
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Hereditary
Magnitude
Sex
Work NV
Diet
Etc.
MYOPIA: CLASSIFICATION
Myopia: classification I
• According to the magnitude of the myopia:
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Low myopia: between -0,25 and -3,00 D
Moderate myopia: between -3,25 and -6,00 D
High myopia: between -6,25 and -10,00 D
Very high myopia: above -10,00 D
Myopia: Classification II
• Clinically:
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Simple myopia
Magna, degenerative, or pathological myopia
Pseudomyopia
Noctunal myopia
Myopia: classification III
SIMPLE MYOPIA
• Most common type of myopia
• Is recognized by:
– Good VA in DV with correction
– Absence of structural anomalies of the ocular
sphere (no pathologies)
– Retinoscopy  subjective
– Progresses limitedly
• School age: 0.50 D/year
• After 18-20 years of age it has few variations
Myopia: Classification IV
MAGNA OR DEGENERATIVE MYOPIA
• Secondary to an excessive axial longitude
of the eye
• Associated to alterations or degeneration of
certain ocular structures
• With the passage of time the VA can be
diminished
• Alterations to the posterior pole (mainly):
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Myopic cone
Loosening of the retina
Macular alterations
Etc
Myopia: Classification V
• Pseudomyopia
– Result of an accomodative spasm
– Subjective exam is more negative than the
retiniscopy
• Nocturnal myopia
– VA reduction in conditions of low illumination
MYOPIA: SIMPLE MYOPIA
Simple myopia: Characteristics I
Factors associated with the prevalence of simple myopia
Age
•2%-5% at 6 years of age
•25%-35% in young adults
Sex
•Greater in women
Race
•Greater in white races, Japanese, Jews, and Chinese.
•Lesser in darker races
Reading
and
education
•Increases when the reading and educational levels
increase
Occupation
Greater in cases which consist of activity in NV
Simple myopia: Characteristics II
• Age
– School age:
• At 6 years of age: 5% myopes
• At 18 years of age: 25-35% myopes
– 20-60 years of age: stabalization
– > 65 years of age: do not forget the relationship between nuclear
cataracts and myopia
Simple myopia: Characteristics III
• Possible risk factors for the development of
myopia:
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Family history of myopia
Emmetropia at pre-school age
Astigmatism against the rule
Altered accomodative function
Endophoria in NV
Prolonged work in NV and at very short distances
Obstruction in the formation of images during the
first few years
Simple myopia: Symptoms and signs
• Symptoms
– Blurry vision in DV
– Rarely symptoms in NV
• Signs
– Blinks to reduce the palpebral
aperture
– Good VA in NV
– Mydriasis
– Exodeviation
– Bringing glasses closer
Simple myopia : Clinical exam
• Retinoscopy and subjective have similar value
• With the adequate Rx the VA tends to reach
20/20 or even 20/15
• Absence of related anomalies in the
funduscopy.
• If the subject has never worn glasses he/she
could show a reduced amplitude of
accomodation for his/her age
Simple myopia: Clinical treatment I
• Age:
– Children < 2 years of age: hypercorrect by 1-2 D
– Children up to 5-years-old (pre-schoolers): hypercorrect by
0,5-1 D
– From 6 to 40 years of age: avoid hypercorrections. Evaluate:
• Visual needs
• Binocularity
– > 40-years-old: Precaution if he/she has never had a myopic
Rx before
Simple myopia: Clinical treatment II
• Anisometropia:
– Up to 8-10 years of age: try to prescribe for the
anisometropia
– > 10 -12 years of age: prudence in the
prescription. Possible existence of monovision
Simple myopia: Clinical treatment III
• Binocularity:
– Exodeviations: Total Rx for general use.
• In young subjects with exotropia: evaluate a
possible slight hypercorrection.
– Endodeviations: avoid hypercorrections.
• In NV try a slight hypocorrection
MYOPIA: MYOPIA DEGENERATIVE
Degenerative myopia: Generalities I
• Elevated myopia associated to pathological
degenerative changes mainly in the posterior
segment of the eye
• Abnormally large axial longitude
• Ocular complications increase with age
• Frequent cause of legal blindness
Degenerative myopia: Generalities II
• Etiology/risk factors:
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Family history
Prematurity and low weight
Albinism
Mental retardation
Certain ocular pathologies
• Age of beginning:
– 0-5 years of age: 31%
– 6-11 years of age: 61%
– 12 or more years of age : 8%
Degenerative myopia: Generalities III
• Symptoms:
–  VA in DV, even with the best refraction:
• From problems in the posterior segment
• Minifying effect of the lenses (-)
– Good VA in NV but at reduced distances
– Discomfort with the glasses:
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Peripheral distortion
Weight
Chromatic aberration
Minification of the environment
Degenerative myopia: Clinical exam
• Signs:
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Occasionaly exophthalmos
VA  with the best refraction
More negative retinoscopy than the subjective
Vertex distance critical during the subjective
Anterior segment:
• Flatter and thinner cornea
• Mydriasis
• Deep anterior chamber
– Posterior segment:
•  relationship cup/disc (in the ophthalmoscopy)
• Myopic cone
• Posterior staphyloma
• Etc.
Degenerative myopia: Clinical treatment
• Avoid hypercorrections
• If prescribing glasses: control the vertex
distance
• Importance of prismatic effects in secondary
sight positions
• Contact lenses:
– Less distorted vision
– More accomodative demand in NV
MYOPIA: PSEUDOMYOPIA
Pseudomyopia: Generalities I
• Value of the subjective exam is more negative
than the that of the retinoscopy
• Possible spasm of the Ciliary muscle
• Do not confuse pseudomyopia with myopic
hypercorrection
Pseudomyopia: Generalities II
• Etiology:
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Spasm of the Ciliary muscle after tasks in NV
Exodeviations
Effects of medication
Inadequate work conditions in NV
• Symptoms:
–  VA in DV (constant or intermittent)
– Asthenopia in NV
Pseudomyopia: Clinical exam I
• VA  in DV
• Retinoscopy:
– Can fluctuate
• Subjective:
– More negative than in the retinoscopy
– The VA does not justify the refractive changes
• Accomodation:
– With the Rx of the subjective it can seem like the
amplitude of accomodation is reduced
Pseudomyopia: Clinical exam II
• Binocularity:
– Can be associated with exodeviations (secondary
condition pseudomyopia)
– Can be associatated with endodeviations (primary
condition pseudomyopia)
Pseudomyopia: Clinical treatment
• Treatment:
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Negative minimum
If prescription: use mainly in DV
Norms of visual hygiene
Visual exercises to relax accomodation
MYOPIA: NOCTURNAL MYOPIA
Nocturnal myopia: Generalities
• Diminishment of VA in conditions of poor
illumination that improves with contact lenses
• Etiology:
– Spherical aberration
– Dark focus of the accomodation
• Detection depends on the subject’s
symptomology
Nocturnal myopia: Clinical treatment
• Specific Rx for nocturnal activities
– Tends to be sufficient with a prescription of -0,75
or -1,00 D
MYOPIA: CASES
Myopia: case 1-I
• MT, 13-years-old. Student.
• MC: Revision. Occasionally notes that he/she
does not see well in DV
• PH: Has never worn glasses. It is his/her first
visual revision (previous check-ups by the
pediatrician). No illnesses or ingestions of
medication.
• FH: Father and older brother are myopes.
Maternal grandmother has cataracts.
Myopia: case 1-II
• Normal VA in DV and NV:
– RE: 20/30+; NV: 20/20
– LE: 20/25; NV: 20/20
• Binocularity in habitual conditions:
– Cover test:
• DV: ORTHO
• NV: Low endophoria
– Promixal convergence: 6/10cm
Myopia: case 1-III
• Retinoscopy:
– RE: -0,50-0,50x90º
– LE: -50x90º
• Subjective DV and VA:
– RE: -0,50-0,25x75º; VA: 20/20+
– LE: -0,50x100º; VA: 20/20+
• Habitual amplitude of accomodation:
– RE: 8cm≈12,5D
– LE: 8cm≈12,5D
• Ocular health tests: within normal limits
Myopia: case 1-IV
• Complete diagnostic of the case
• Treatment proposed and plan of revisions
• Possible evolution of the condition
Myopia: case 1-V
• Complete diagnostic of the case
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Low inverse astigmatism in both eyes
Low myopia in RE
Endophoric tendency in NV
The rest of the tests are within normal limits
Myopia: case 1-VI
• Treatment proposed. There are two possibilities:
– Option A:
• Do not prescribe glasses
• Recommend sitting as close as possible to the board in
class
• Recommend rules of visual hygiene: postures and work
distance
• Explain the condition and desired conduct to the patient
• Revision in 3-4 months
Myopia: case 1-VII
• Treatment proposed. There are two possibilities:
– Option B:
• Prescribe glasses: RE: -0,50-0,25x75º; LE: -0,50x100º
• Exclusive use for DV. In class when necessary to in order to
pay attention to the board.
• Do not use the glasses while studying in NV
• Recommend standards for visual hygiene: postures and
work distance
• Explain the condition and the desired conduct to the patient
• Revision in 4-6 months
Myopia: case 1-VIII
• Possible evolution of the condition:
– Progression of the myopia
Myopia: case 2-I
• SE, 23 years of age. Salesman.
• MC: notes that he/she does not see will in DV,
mainly while driving.
• PH: Has worn general use glasses for 10
years. The most recent pair are three-yearsold. No illnesses or ingestion of medication.
• FH: Irrevelant.
Myopia: case 2-II
• Rx and VA are habitual in DV and NV:
– RE: -2,25;
VADV: 20/25-;
VANV: 20/20
– LE: -1,75-0,50x10º; VADV:20/30+; VANV: 20/20
• Binocularity in habitual conditions:
– Cover test:
• DV: Ortho
• NV: Low exophoria
– Proximal convergence: up to the nose
Myopia: case 2-III
• Retinoscopy:
– RE: -2,75-0,25x180º
– LE: -2,25-0,50x180º
• Subjective DV and VA:
– RE: -2,50-0,25x15º; VA: 20/20+
– LE: -2,25-0,50x15º; VA: 20/20+
• Habitual amplitude of accomodation:
– RE: 9cm≈11D
– LE: 9cm≈11D
• Ocular health tests: within normal limits
Myopia: case 2-IV
• Complete diagnostic of the case
• Treatment proposed and a plan of revisions
• Possible evolution of the condition
Myopia: case 2-V
• Complete diagnostic of the case
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Simple myopia low in AO
Low, direct astigmatism in both eyes
Exphoric tendency in NV
The rest of the tests within normal limits
Myopia: case 2-VI
• Treatment proposed:
– Prescribe new glasses:
• RE: -2,50-0,25x15º
• LE: -2,25-0,50x15º
– For general use
– Explain the change made
– New check-up in 2 years or before if new
symptoms appear
Myopia: case 2-VII
• Possible evolution of the condition:
– Significant refractive changes are not expected until
the age of prebyopia
MYOPIA: BIBLIOGRAPHY
Myopia: bibliography
• Amos JF. Diagnosis and management in vision care.
Butterworth-Heinemann, 1987
• Milder B, Rubin ML. The fine art of prescribing
glasses. (2nd edition), Triad Publishing company,
1991.
• Grosvenor T. Flom MC. Refractive anomalies.
Research and clinical applications. ButterworthHeinemann, 1991
• Brookman KE. Refractive management of ametropia.
Butterworth-Heinemann, 1996
• Werner DL, Press LJ. Clinical pearls in refractive care.
Butterworth-Heinemann, 2002
Myopia: Bibliography
• http://www.wrongdiagnosis.com/r/refractive_
eye_disorders/intro.htm
• http://www.nlm.nih.gov/medlineplus/ency/art
icle/001023.htm
• http://www.tarso.com/Miopia.html