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  • MYOPIA, HYPERMYOPIA, ASTIGMATISM, PRESBYOPIA, CONVERGENCE INSUFFICIENCY AND SPASM OF ACCOMODATION.

Transcript

  • 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
  • 4. 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
  • 5. 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.
  • 6. 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.
  • 7. 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.
  • 8. 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.
  • 9. TREATMENT OF MYOPIA SPECTACLES, CONTACT LENS & SURGICAL TREATMENT. – Radial keratotomy – Photorefractive keratotectomy – LASIK – Clear lens extraction – Phakic IOL Implantation.
  • 10. 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.
  • 11. 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.
  • 12. 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.
  • 13. 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.
  • 14. 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.
  • 15. 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.
  • 16. Hyperopia or Hypermetropia Spectacles Contact lens PRK Lasik Holmium laser thermal keratoplasty
  • 17. ASTIGMATISM SPECTACLES RIGID CONTACT LENS ARCUATE KERATOTOMY PRK LASIK
  • 18. 32
  • 19. APHAKIA
  • 20. PRESBYOPIA
  • 21. ANISOMETROPIA CONTACT LENS MONOVISION
  • 22. ANOMALIES OF ACCOMMODATION
  • 23. RK PHOTO(6.16-K)