1
ERRORS OF REFRACTION AND ACCOMODATION
REFRACTION IT   IS CHANGE IN DIRECTION OF LIGHT AS IT ENTERS A MEDIUM OF DIFFERENT DENSITY
DEFINITIONS EMMETROPIA AMETROPIA: – AXIAL: 22-24mm.2.5-3.00D/mm – CURVATURE: K.conus, spherophakia – INDEX: N.sclerosis,...
MYOPIA Simple myopia upto 5D Developmental myopia –10D at birth Pathological axial myopia: starts at 5-10 yr of age  an...
CHANGES IN MYOPIA Axial myopia affects post. half more oftenly and  adversely as compared to ant half. Post staphyloma ...
CHANGES IN MYOPIA--- CONTINUED---Eyes look prominent, AC deep and pupils wide.Pseudoesotropia. Poor visual acuity in spi...
SYMPTOMS Indistinct   distant vision. Disproportionate     accommodation and  convergence may lead to discomfort in near...
TREATMENT OF MYOPIA SPECTACLES,            CONTACT LENS & SURGICAL TREATMENT.  –   Radial keratotomy  –   Photorefractive...
RADIAL KERATOTOMY PROCEDURE:  Multiple deep stromal radial cuts starting from optical  zone (Central 4mm) up to limbus by...
RADIAL KERATOTOMY cont.. SUCCESS     RATE:      50% stable by about six month. PER-OPERATIVE COMPLICATIONS:      Acciden...
PHOTOREFRACTIVE KERATECTOMY PROCEDURE:  Optical zone anterior stromal ablation by Excimer Laser  after de- epithelial rem...
PHOTOREFRACTIVE KERATECTOMY cont.. SUCCESS      RATE:     90% achieve final refractive error of 1D. Long  term drift espe...
LASER IN-SITU KERATOMILEUSIS PROCEDURE:  Same as PRK except that laser is applied after a hinged  corneal flap by micro k...
LASER IN-SITU KERATOMILEUSIS cont.. SUCCESS   RATE:    Results are better than PRK. COMPLICATIONS:     Buttonholing, amp...
Hyperopia or Hypermetropia Spectacles Contact   lens PRK Lasik Holmium    laser thermal keratoplasty
ASTIGMATISM SPECTACLES RIGID   CONTACT LENS ARCUATE   KERATOTOMY PRK LASIK
32
APHAKIA
PRESBYOPIA
ANISOMETROPIA CONTACT LENS MONOVISION
ANOMALIES OF ACCOMMODATION
RK PHOTO(6.16-K)
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  • MYOPIA, HYPERMYOPIA, ASTIGMATISM, PRESBYOPIA, CONVERGENCE INSUFFICIENCY AND SPASM OF ACCOMODATION.
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    1. 1. 1
    2. 2. ERRORS OF REFRACTION AND ACCOMODATION
    3. 3. REFRACTION IT IS CHANGE IN DIRECTION OF LIGHT AS IT ENTERS A MEDIUM OF DIFFERENT DENSITY
    4. 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. 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. 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. 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. 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. 9. TREATMENT OF MYOPIA SPECTACLES, CONTACT LENS & SURGICAL TREATMENT. – Radial keratotomy – Photorefractive keratotectomy – LASIK – Clear lens extraction – Phakic IOL Implantation.
    10. 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. 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. 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. 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. 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. 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. 16. Hyperopia or Hypermetropia Spectacles Contact lens PRK Lasik Holmium laser thermal keratoplasty
    17. 17. ASTIGMATISM SPECTACLES RIGID CONTACT LENS ARCUATE KERATOTOMY PRK LASIK
    18. 18. 32
    19. 19. APHAKIA
    20. 20. PRESBYOPIA
    21. 21. ANISOMETROPIA CONTACT LENS MONOVISION
    22. 22. ANOMALIES OF ACCOMMODATION
    23. 23. RK PHOTO(6.16-K)
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