3. Definetion
Myopia ( short sight ) condition where parallel rays come to
focus in front of the sentient layer of retina when
accommodation is at rest
Muopia (Greek) = To close the eye
4. History
Kepler (1611), Plempius (1632) - lengthening of posterior part.
Donders (1866) est.. Pathological basis, and detail clinical
manifestation's
6.
lenticular curvature
eg : ant/post lenticonus – marked
Positional : dislocation of lens
Myopia due to excessive accommodation - spasm of
accommodation,
suspensory lig. Rupture
7.
Index myopia : change in the R.I of the crystalline lens
eg : Nuclear Sclerosis,
Incipient Cataract,
Diabetes.
8.
Buphthalmos : cong/ infantile glaucoma.
Defective development – A.P diameter
myopia not in ratio
enlarged and
9. Optics
Optical system – eye too powerful for axial length
Image of distant object on retina are circles of
diffusion form by divergent beam
Far point is finite pt in front of eye – object at far pt
focused without acc.
Angle of alpha –ve resulting in convergent squint
10.
Accommodation- uncorrected- not
developed , as not needed for Nv.
Thus may develop exophoria,
convergence insufficiency and
presbyopia
Enlarged image is cause of nodal pt being far
away from retina
13. Congenital myopia
Since birth
Diagnosed – 2 -3 yrs.
Associated – prematurity, birth defects,
congenital squint, and axial length
Unilateral or bilateral
Unilateral – manifest as anisometropia
diagnosed - after squint- amblyopia
14.
Associated – cataract, microphthalmas, cong. Retinal
separation, megalo-cornea
Prognosis – early detection
no 6/6 uni-ocular
15. Simple Myopia
Physiological / developmental / school
Biological variation in development
Limited progression no disease
Factors associated :
Axial – A.P diameter (or) neurological
Curvatural – underdevelopment of eye ball
Diet – poor nutriention
Genetic influence – one (or) both parents
16. Physiological – A/S normal along
with normal fundus
Simple
Myopia
Intermittent –
early signs of
globe
enlargement
temporally
Sever category
of intermittent –
crescent with
super-traction
of disc
17. course
Born hyper
metropic
Emmetropic
• overshoot
Stabilized at
teens
Myopic
• 7-10 yrs
• -5D to -8D
symptom's :
Poor distance vision – beyond far point impaired
Asthenopic sympt – eye strain due to difference b/w convergence and
accommodation
Nv -No accommodation – convergence weakness – exophoria – suppression of
one eye
Nv –convergence – excessive accommodation – ciliary spasm
Physiological out-look – myopic child behavior
18.
Signs
A.C. – deep
Pupil – large and sluggish
Fundus – normal
Eye – large and prominent
Error - -5.00 D to -8.00D
Diagnosis –visual acuity
subjective testing
retinoscopy
20.
Prevalence –
earlier and higher in females
higher – Asians, Arabs, Jews
lower – Africans, Caucasians
more in urban populations
21. Etiology
Results from rapid growth of eye out side its biological variation
2 theories
- Hereditary
- General growth
Genetic
factors
Retinal growth
Scleral
stretching
Increase in
axial length
Pathological myopia
• Degeneration – choroid, retinae,
vitreous
22.
Symptoms
Muscae volitantes – deg. lig. Vitreous
Diminished Vn – progressive due to degeneration
Night blindness – high myopes with choroidi-retinal changes
Signs
Prominent, elongated(post), unilateral, stimulating exophthalmos
Cornea – large; A.C – deep; pupil – large, sluggish
Refractive error – by -4D/yr up to 20-30yrs
23.
Fundus –
Generalized atrophy of choroid and retinae
Loss of RPE- fundus tugroid- prominent choroidal vessels
Choroid disappears – visible sclera – atrophic patch - post. Pole –
macula (common)
Foster – Fuchs's spots – rare, sudden, dark pig.
sub-retinal neovascularization and choroidal hx.
Cystoid degeneration at periphery
24.
Advance cases – total retinal atrophy, central
Lattice degeneration/ snail track lesion
25.
Optic disc
Myopic crescent – from elongation of disc
separation of retina and choroid from temp
may be annular
Super traction crescent – nasal retina extending over the disc –
blur margin
Posterior staphyloma – higher degree,
herniation of post. Pole – sudden kinking of vessels at margin as in
glaucoma
26.
Vitreous – degeneration, PVD-Wiess reflex, liquefaction, opacities
Visual field – ring scotoma
Electo-retinograph – chorioretinol atrophy
Complications
retinal tears, detachment, Hx (high myopia)
vitreous detachment, degeneration
complicated cataract –↓ lenticular metabolism
Nuclear sclerosis – common, effects refraction
Choroidal Hx – sever Vn loss if in fovea
POAG – not common but seen
27. acquired
index – nuclear sclerosis, incipient cataract, diabetic myopia
Curvatural – true inc. in corneal curvature (or) lenticular
Positional – subluxation(ant) of lens
Consecutive – surgical overcorrection(cataract/ hypermetropia)
Pseudo-myopia – due to excessive accommodation and spasm of
accommodation
Space myopia – no stimulus for Nv, its variable, trouble in flying and in fog
Night/twilight – shift from photic to scotopic vn is associated with inc. sensitivity to
shorter wavelength viz myopic
Cholinergic – pilocarpine, echothiosulphate
Drug induced -
Steroid – show changes in crystalline lens
Sulplanamides – changes the refractive indices in media
28. Diagnosis
presentation
Simple – blurred Dv, constant/ transient, Nv
may be normal, co-existing condt.
Nocturnal – blurred Dv in dim illumination,
difficulty in driving
Pseudo myopia – transient Dv blur, inc after
near work
Degenerative - considerable Dv blur,
flashes/ floaters, Vn loss
Induced – transient Dv blur until drug effect,
pupils constricted – cholinergic antagonist
29. Ocular
examination
Visual acuity – both unaided Nv and Dv should
be measured-mean gives reduced V.A
Refraction – retinoscopy or and A.R. , but A.R
not qualitative
retinoscopy – diagnosis for nocturnal myopia
with cyclopegics
Ocular motility, binocular Vn, accommodation
– heterophoria, versions, accommodative
facility test
systemic and ocular health – IOP, SLB, postsegment
31. Treatment
Optical Correction
Proper correction with concave lens for image to fall on retina
Myopia up to -6.00D
Children – full correction
Young adults – prevent over correction
Adults - ↓ 30 yrs. – full correction
↑ 30 yrs. – under corrected – ciliary muscles fail to
accommodate
32.
Spectacle's
Contact lens
Economical, safe
Larger retinal image
Allow incorporation
Better Vn in Sr. myopia
Better correction of astigmatism
Better visual field
Less acco- near pt. blur in
presbyopia
Dec. prismatic effect
Rigid lens dec. progressive
myopia
35.
Radial keratotomy
Deep radial incisions (90% thickness) sparing central 4mm –
cornea flatter's on healing
Disadvantages – globe rupture, irregular astigmatism, glare,
bullous keratopathy
36. Photorefractive keratectomy (PRK)
First refractive procedure to use the excimer laser
Max success in myopia
Good for -2.00D to -6.00D
Photoabalation of central optical zone of ant.
Corneal stroma
De-epithelialzation – photo
ablative
Ablation – 6mm for myopia
0.5.1.0mm more
Laser should be coaxial with
pupil
Prevent extreme drying or
wetting of cornea and residual
islands
Hand held ring for centration
Toric photoabalation
corneal curvature shifts as ant
stroma collapse and thins
Intrastromal PPk – double
NdYAG
Plasmamediated
photodistribution shock wave
Complications – decentation
Corneal haze, infiltrates, ulcers
Night glare , halos
Delayed epi healing
Islands, Hx, IOP↑
37. Combination – Incisional & Ablative
Procedure
LASIK
- Laser In Situ Keratomileusis
Microkeratome to make a corneal flap – excimer to ablate the
refractive error
adv – bilateral, PRK healing risks avoided, stable results
Dis-adv – flap related, striae, diffuse lamellar keratitis, under (or)
over correction
38.
LASEK – LASER Epithelial Keratomileusis
Similar to PRK – epithelium is removed and replace post Sx
Alcohol to store the epithelium
For large pupils and thin corneas
For > -8.00 D
Adv – no risk of flap dislocation (LASIK)
Thin flap
Less chance of ectasia
Dis- adv – visual recovery slower than LASIK
39.
Epi LASIK
Cleaves epi from bowmen's – structural integrity maintained
Newer version of LASEK- advantage on LASIK
More thin flap, less haze, faster recovery
Custom LASIK
Customized for each eye
Less halos and glare, More chance of 6/6
Wave front aberrometer - corneal topography
Ablation – flexible laser system
40. Intra ocular refractive Sx
Refractive lens exchange
Existing cataract and cornea unfit for refractive Sx
For -16.00D to -30.00D
PCO reduced
Accommodation retained thrgh ‘hinges’
41.
Phakic IOLs
Patients not qualified for refractive Sx
Ant / Post chamber lens with out removing crystalline lens
Made of plastic (or) silicone
42. Patient history and examination
Supplement
al testing
Management flow
chart
Simple
myopia
Correction
Infants and
toddlers – no
correction < 3D
Pre-school/earlyschool – correct if
>1-2D
Adolescent's/adult
s – correct
significantly
Control
plus lens for Nv
Rigid contact
lens
Visual hygiene
Assessment and diagnosis
Patient counseling and education
Treatment and management
Nocturnal
myopia
Reduction
Corneal
modification
– refractive
Sx
Pseudomyopia
Myopia
correction
for night
time seeing
only
Reduction of
accommodative
response – vision
therapy, plus lens
for Nv,
cycloplegic
agents, visual
hygiene
Degenerative
myopia
Induced
myopia
Identificatio
n and
treatment of
causative
agent
Correction
and
manageme
nt of retinal
changes
43. If a man is called to be a street sweeper, he
should sweep street so well that all the host
of heaven and earth will pause to say, here
lived a great street sweeper who did his job
well.
- Martin Luther King, Jr.
