Indication of RGP Lens in corneal abnormalties.pptx

Indication of contact lenses in corneal abnormalities like Keratoconus, Keratoglobus,

1. INDICATION OF RGP LENS BY SATYENDRA SINGH SACHAN Asst Professor Rama University

2. Oxygen supply to the cornea Astigmatic correction regular irregular

3. KERATOCONUS Keratoconus is a benign, usually bilateral, non-inflammatory thinning and ectasia of the cornea, resulting in a high degree of irregular myopic astigmatism

4. Prevalence of keratoconus   in Central  India  (0.0003%-2.3%) Gokhale NS. Epidemiology of keratoconus . Indian J Ophthalmol 2013 [cited 2020 Feb 3];61:382-3.

5. KERATOCONUS CLEK DATA: CORNEA 44.37 D(SD 1.6 D) 0.50 D Cyl (SD 0.18 D) Axis 175 ° Corneal Tilt: 0.38  (SD 0.11) Base-Apex line: 56° - 236° 48.02 D (SD 3.88 D) 2.46 D Cyl (SD 0.99 D) Axis 26 ° Corneal Tilt: 3.94  (SD 1.45) Base-Apex line: 69° - 249° Normals: 60 Eyes Keratoconics: 690 Eyes Raasch et al ., 1998

6. KERATOCONUS CLASSIFICATION BY CORNEAL CURVATURE • Mild: <45 D • Moderate: 45 – 52 D • Advanced: 52 – 65 D • Severe: > 62 D

7. Symptoms Initially, asymptomatic • Visual degradation reported at or after time of puberty • Progresses slowly over 5 – 10 years Ghost image & photophobia

8. Sign • Distorted keratometry mires • Distorted photokeratoscopy rings • Inferior steeping in videokeratoscopy maps • Apical corneal thinning ( stromal ) • Cone formation

9. KERATOGLOBUS It is a familial and hereditary bilateral congenital disorder characterized by thinning and hemispherical protrusion of the entire cornea. It is non-progressive and inherited as an autosomal recessive trait.

10. PENETRATING KERATOPLASTY Trephine Host button Donor button Double-armed suture Donor Host Corneal button Diam.=Host+0.5 mm Sutures Corneal penetration > full thickness

11. BULLOUS KERATOPATHY

12. BULLOUS KERATOPATHY (BK) POST-GRAFT Note: Avascular donor tissue One remaining suture

13. CORNEAL TOPOGRAPHY Incorrect placement of cardinal sutures Non-radial sutures Unequal suture tension(s) Pre-existing astigmatism in host or donor cornea Scar tissue in host cornea CAUSES OF ASTIGMATISM

14. CORNEAL TOPOGRAPHY: AFTER PK

15. GRAFT WITH 5 D CYL

16. RGPs (high Dk /t ) when: patient wore RGPs previously postsurgical scarring present corneal irregularities present post-PK corneal ectasia Scleral lenses (gas permeable) in cases of: irregular corneas sensitive corneas after Bufidis et al., 2005

17. LENS SELECTION Rigid gas permeable lenses are the modality of choice following penetrating keratoplasty maximum correction of cylinder

18. RGP LENS Oxygen supply Correction of astigmatism Level of visual acuity

19. RGP LENS Correction of irregular astigmatism Provide high oxygen transmissibility Custom designs available

20. REFERNCE IACLE MODULE

21. THANK YOU