myopia. myopia : program myopia: program i generalities –definition –etiology –epidemiology...
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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:
• 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:– Hereditary– Magnitude– Sex– Work NV– Diet– Etc.
MYOPIA: CLASSIFICATION
Myopia: classification I
• According to the magnitude of the myopia:– 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:– Simple myopia– Magna, degenerative, or pathological
myopia– Pseudomyopia– Noctunal myopia
Myopia: classification III
• 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
SIMPLE MYOPIA
Myopia: Classification IV
• 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):– Myopic cone– Loosening of the retina– Macular alterations– Etc
MAGNA OR DEGENERATIVE MYOPIA
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:– 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:– 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:
• Peripheral distortion• Weight• Chromatic aberration• Minification of the environment
Degenerative myopia: Clinical exam
• Signs:– 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:– 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:– 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– 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-years-old. 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– 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. Butterworth-Heinemann, 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/article/001023.htm
• http://www.tarso.com/Miopia.html