1. MYOPIA

2.  SHORT SIGHTEDNESS
 DIOPTERIC CONDITION IN WHICH INCIDENT
PARALLEL RAYS COME TO A FOCUS ANTERIOR TO
THE LIGHT SENSITIVE LAYER OF RETINA WITH
ACCOMODATION AT REST.
MYOPIA

3. 1. AXIAL MYOPIA
 COMMONEST FORM
 INCREASE IN ANTERO-POSTERIOR LENGTH OF THE
EYEBALL
2. CURVATURAL MYOPIA
 INCREASED CURVATURE OF CORNEA, LENS OR BOTH
3. POSITIONAL MYOPIA
 PRODUCED BY ANTERIOR PLACEMENT OF CRYSTALLINE
LENS IN EYE
4. INDEX MYOPIA
 INCREASE IN THE REFRACTIVE INDEX OF CRYSTALLINE
LENS ASSOCIATED WITH NUCLEAR SCLEROSIS
5. MYOPIA DUE TO EXCESSIVE ACCOMODATION
 SPASM OF ACCOMODATION
ETIOLOGICAL CLASSIFICATION

4. 1. Congenital myopia
2. Simple or developmental myopia
3. Pathological or degenerative myopia
4. Acquired myopia which may be
 Post traumatic
 Post keratitic
 Drug induced
 Pseudomyopia
 Space myopia
 Night myopia
 Consecutive myopia
CLINICAL VARIETIES

5.  Since birth
 Diagnosed by 2-3 years
 Mostly unilateral
 Manifests as anisometropia
 Child may develop convergent squint in order to
preferentially see clear at its far point (10-12cms)
CONGENITAL MYOPIA

6.  Associated with cataract, micropthalmos, aniridia,
megalocornea, congenital separation of retina.

7.  Developmental myopia- commonest variety
 School myopia (school going age 8-12 years)
 Etiology
 Axial type:
 physiological variation in length of eye ball
 precocious neurological growth during childhood
SIMPLE MYOPIA

8.  Curvatural type
 Underdevelopment of eye ball
 Role of diet in early childhood
 Role of genetics
 Prevalence in children
 both parents myopic(20%)
 One parent myopic(10%)
 No parent myopic(5%)

9. Symptoms
 Poor vision for distance(short sightedness)
 Asthenopic symptoms
 Half shutting of eyes
CLINICAL PICTURE

10. Signs
 Prominent eyeballs
 Anterior chamber - deeper than normal
 Pupils- Large, sluggishly reacting
 Fundus- normal; rarely temporal myopic crescent may be seen
 Magnitude of refractive error
 Increasing at rate -0.5+- 0.30/ year.
 Does not exceed 6 to 8
Diagnosis
Confirmed by performing retinoscopy

11.  Degenerative/ progressive myopia
 Rapidly progressive error which starts in childhood at
5-10 years of age
 High myopia in early adult life with degenerative
changes
PATHOLOGICAL MYOPIA

12.  Role of heredity
 Heredity linked growth of retina is the determinant in
developmental myopia
 Sclera due its distensibility follows retinal growth but
choroid undergoes degeneration due to stretching,
which in turn causes degeneration of retina
 Progressive myopia is
 Familial
 More common in chinese,japanese,arabs and jews
 Uncommon among negroes,nubians and sudanese
ETIOLOGY

13.  Role of general growth process
Lengthening of the posterior segment of globe
commences only during the period of active
growth and ends with termination of active
growth

14. Genetic factors (play major role)
General growth process(minor)
More growth of retina
Stretching of sclera
Increase axial length
Degeneration of choroid
Degeneration of retina
Degeneration of vitreous

15.  Defective vision
 Muscae volitantes
 Floating black opacities in front of eyes
 Degenerated liquified vitreous
 Night blindness
SYMPTOMS

16.  Prominent eye balls
 Elongation of eye ball mainly affects posterior pole
and surrounding area
 Cornea-large
 Anterior chamber -deep
 Pupils-slightly large ,react sluggishly to light
SIGNS

17. Fundus examination:
Optic disc
 large and pale
 Temporal edge presents a characteristic myopic crescent
 Peripapillary crescent encircling the disc may be present, where
choroid and retina is distracted away from disc margin
 Super traction crescent may be present on nasal side (retina pulled
over disc margin)

21. Degenerative changes in retina and choroid
 Common in progressive myopia
 Characterized by white atrophic patches at macula with
a little heaping of pigment around them

22. • FOSTER-FUCH’S
SPOT:
• Dark red circular
patch due to sub-
retinal neo
vascularization and
choroidal
haemorrhage
• Present at macula
• CYSTOID
DEGENERATION –
at periphery
• Advanced cases:
Total retinal
atrophy in central
area

23.  Posterior staphyloma
 Due to ectasia of sclera at posterior pole
 It may be apparent as an excavation with vessels bending backward
over margins

24.  Degenerative changes in vitreous include:
 Liquefaction
 Vitreous opacities
 Posterior vitreous detachment(PVD)- Weiss’ reflex

25.  Visual fields
 Contraction
 Ring scotoma may be seen
 ERG reveals subnormal
electroretinogram due to
chorioretinal atrophy

26.  Retinal detachment
 Complicated cataract
 Vitreous haemorrhage
 Choroidal haemorrhage
 Strabismus fixus convergence
COMPLICATIONS

27.  Optical treatment of myopia
 Concave lenses
 Basic rule – minimum acceptance providing maximum
vision
 Modes of prescribing concave lens-
1. Spectacles
2. Contact lens
TREATMENT OF MYPOIA

28.  Contact lenses are used in case of high myopia as they
avoid peripheral distortion and minification produced
by strong concave spectacle lens

29.  Radial keratotomy
 Making deep radial incisions in peripheral part of
cornea leaving the central a 4mm optical zone
 These incisions on healing ; flatten the central
cornea thereby reducing its refractive power
 Correct low to moderate myopia(2-6D)
DISADVANTAGES:
 Cornea is weakened – globe rupture in sports persons
 Uneven healing – irregular astigmatism
 Patient may feel glare at night
SURGICAL TREATMENT OF
MYOPIA

31. Photo refractive
keratectomy (PRK)
 A central optical zone
of anterior corneal
stroma is photoablated
using excimer laser
(193nm uv flash) to
cause flattening of
central cornea
 Correction for -2 to -
6D of myopia

32. Disadvantages:
Post operative recovery is slow
Pain and discomfort
Residual corneal haze in centre affecting vision
Expensive

33.  Refractory surgery of choice for myopia of upto -12D
LASER ASSISTED IN-SITU
KERATOMILEUSIS(LASIK)

34. Flap of 130-160 micron thickness of
anterior corneal tissue is raised
Midstromal tissue is ablated
directly with an excimer laser beam
ultimately flattening the cornea

36. 1. Patients >20 years
2. Stable refraction for at least 12 months
3. Motivated patient
4. Absence of corneal pathology
 Absolute contraindication for LASIK
 Presence of ectasia
 Corneal thickness <450mm
PATIENT SELECTION
CRITERIA

37.  Customised(C)-LASIK:
 Based on wave front
technology
 Corrects spherical,
cylindrical and other
aberations present
in eye
 Gives vision beyond
6/6 i.e.,6/5 or 6/4
ADVANCES IN LASIK

38.  Epi-(E) LASIK:
 Only epithelial sheet is
separated with Epiedge
Epikeratome
 Devoid of complications
related to corneal
stromal flap

40.  Minimal or no postoperative pain
 Recovery of vision is very early as compared to PRK
 No risk of perforation during surgery and rupture of
globe due to trauma like RK
 No residual haze unlike PRK where subepithelial
scarring may occur
 LASIK is effective in correcting myopia of -12D
ADVANTAGES OF LASIK

41.  Expensive
 Requires greater surgical skill than RK and PRK
 Flap related complications
 Intraoperative flap amputation
 Wrinkling of flap on repositioning
 Postoperative flap dislocation/subluxation
 Epithelization of flap – bed interface
 Irregular astigmatism
DISADVANTAGES

42.  Fucala’s operation
 Myopia of -16 to -18D in unilateral cases
 Clear lens extraction with intraocular lens implantation
of appropriate power is the refractive surgery for
myopia of >12D
EXTRACTION OF CLEAR
CRYSTALLINE LENS

43.  Intraocular contact lens implantation for correction of
myopia of >12D
 Special type of IOL is implanted in anterior chamber or
posterior chamber anterior to natural crystalline lens
PHAKIC INTRAOCULAR LENS

44.  Into the peripheral cornea at approximately 2/3rd
stromal depth
 Flattening of central cornea, decreasing myopia
 Advantage: reversible procedure
INTRACORNEAL RING (ICR)
IMPLANTATION

45.  A non-surgical reversible method of molding the cornea
with overnight wear unique rigid gas permeable contact
lenses
 Myopia correction upto -5D
 Used in patients below 18 years of age
ORTHOKERATOLOGY

46.  General measures :
 Balanced diet rich in vitamins and proteins
 Early management of associated debilitating disease
 Low vision aids
 indicated in patients with progressive myopia with
advanced degenerative changes
 Prophylaxis
Genetic counselling