eye

1. 1

2. ERRORS OF REFRACTION
AND ACCOMODATION

3. REFRACTION
 IT
IS CHANGE IN DIRECTION OF
LIGHT AS IT ENTERS A MEDIUM OF
DIFFERENT DENSITY

5. DEFINITIONS
 EMMETROPIA
 AMETROPIA:
– AXIAL: 22-24mm.2.5-3.00D/mm
– CURVATURE: K.conus, spherophakia
– INDEX: N.sclerosis, vitrectomy with silicon
oil.
– Ectopia lentis = axial

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.

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.

16. TREATMENT OF MYOPIA
 SPECTACLES,
CONTACT LENS &
SURGICAL TREATMENT.
– Radial keratotomy
– Photorefractive keratotectomy
– LASIK
– Clear lens extraction
– Phakic IOL Implantation.

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.

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.

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.

28. Hyperopia or Hypermetropia
 Spectacles
 Contact lens
 PRK
 Lasik
 Holmium laser thermal keratoplasty

30. ASTIGMATISM
 SPECTACLES
 RIGID CONTACT LENS
 ARCUATE KERATOTOMY
 PRK
 LASIK

32. 32

33. APHAKIA

34. PRESBYOPIA

35. ANISOMETROPIA
 CONTACT LENS
 MONOVISION

36. ANOMALIES OF ACCOMMODATION

37. RK PHOTO(6.16-K)