7. MYOPIA
Simple myopia upto 5D
Developmental myopia –10D at birth
Pathological axial myopia: starts at 5-10 yr of age
and gors on increasing till 25 . May achieve 15-
25D or more.
Pathological curvature myopia. K.conus
Index myopia i.e. nuclear sclerosis, DM, drugs:
Hydralazine, chlorthalidone and phenothiazines.
8. CHANGES IN MYOPIA
Axial myopia affects post. half more oftenly and
adversely as compared to ant half.
Post staphyloma
Myopic crescent
Peripheral retinal degenerations leading to
thinning, hole formation and ret. detach.
Mac. Hole. Vitreous degeneration:
Choroidoretinal atrophy, laquer’s crackes, ch
small vessel haemorrhages and thrombises leading
to Foster-Fuchs spot.
9.
10.
11.
12.
13.
14. CHANGES IN MYOPIA--- CONTINUED---
Eyes look prominent, AC deep and pupils wide.
Pseudoesotropia. Poor visual acuity in spite of
optical correction.Centra/peripheral scotomas.
Pre-senile cataract, increased prevalence of
POAG, PDS/PDG,steroid responsiveness.
Marfan’s, Stickler, Ehlers-Danlos and Pierre-
Robin----Syndromes.
15. SYMPTOMS
Indistinct distant vision.
Disproportionate accommodation and
convergence may lead to discomfort in near
work.(High myopia)
Black spots and flashes in front of eye.
17. RADIAL KERATOTOMY
PROCEDURE:
Multiple deep stromal radial cuts starting from optical
zone (Central 4mm) up to limbus by diamond knife.
Causes bulging of peripheral cornea and flattening of the
central.
INDICATIONS:
Static myopia upto 5D of adults with no or little
astigmatism.
CONTRA-INDICATIONS:
Before 21 year of age, significant astigmatism and
corneal opacity.
18. RADIAL KERATOTOMY cont..
SUCCESS RATE:
50% stable by about six month.
PER-OPERATIVE COMPLICATIONS:
Accidental perforation, involvement of visual
axis and incisions of wrong direction.
POST -OPERATIVE COMPLICATIONS:
Bacterial keratitis, endophthalmitis,
introstromal inclusionst, globe rapture and cataract
formation.
19.
20. PHOTOREFRACTIVE KERATECTOMY
PROCEDURE:
Optical zone anterior stromal ablation by Excimer Laser
after de- epithelial removal. This thins central cornea and
reduces is by diaptoric power.
INDICATIONS:
Static myopia upto 6D , astigmatism upto 3D.
CONTRA-INDICATIONS:
High astigmatism and myopia more than 7D.
21. PHOTOREFRACTIVE KERATECTOMY cont..
SUCCESS RATE:
90% achieve final refractive error of 1D. Long
term drift especially in high myope.
COMPLICATIONS:
Mild pain and watering for few days. Corneal
scarring 3% of cases. Night glare.
22.
23.
24. LASER IN-SITU KERATOMILEUSIS
PROCEDURE:
Same as PRK except that laser is applied after a hinged
corneal flap by micro keratome.
INDICATIONS:
S myopia upto 12D , astigmatism upto 5D.
CONTRA-INDICATIONS:
Eyes with thin cornea.
25. LASER IN-SITU KERATOMILEUSIS cont..
SUCCESS RATE:
Results are better than PRK.
COMPLICATIONS:
Buttonholing, amputation, incomplete irregular
flaps and corneal perforation.
Wrinkling, distortion or dislocation of flap.
Epithelial in growth under flap. Keratitis, anterior
segment ischaemia and optic neuropathy.