Presentation (8). Ppt on topic of ophthalmology

Ppt on topic of cornea

1. Pterygium Roll. No. 1 - 40

2. Pterygium It is a wing shaped fold of conjunctiva encroaching upon the cornea from either side within the interpalpebral fissure.

3. Etiology More common in people living in hot climates and in those who work outdoors. It is a response to prolonged effect of environmental factors such as exposure to sunlight (UV rays) , dry heat, high wind, abundance of dust.

4. Pathology It is a degenerative and hyperplastic condition of conjunctiva which encroaches on cornea and is characterised by: Elastotic degeneration of subconjunctival tissue Fibrovascular proliferation under conjuctival epithelium Corneal tissue destruction involving epithelium, Bowman’s layer and superficial stroma

5. Demography Age: usually seen in old age Sex: more common in males doing outdoor work Laterality: unilateral or bilateral Usually present on the nasal side than temporal side

6. Symptoms Cosmetic intolerance in early stages otherwise asymptomatic condition Foreign body sensation and irritation Defective vision occurs when it encroaches the pupillary area or due to corneal astigmatism induced by fibrosis in the regressive stage Diplopia may occur occasionally due to limitation of ocular movements

7. Signs Triangular fold of conjunctiva encroaching on the cornea in the area of palpebral aperture usually on the nasal side is typical presentation of pterygium. Very rarely both nasal and temporal sides are involved ( Primary Double pterygium) Stocker line (deposition of iron) may be seen in corneal epithelium anterior to the advancing head of pterygium

8. Parts of pterygium Head : Apical part present on the cornea Neck : Constricted part present in the limbal area Body : scleral part, extending between limbus and the canthus Cap : semilunar whitish infiltrate present just in front of the head

9. Types of pterygium Depending on the extent Type 1 – extends <2mm onto the cornea Type 2 – involves upto 4mm of the cornea Type 3 – encroaches >4mm of the cornea and invokes the visual axis

10. Depending upon the progression Progressive pterygium – thick , fleshy and vascular with a few whitish infiltrate in the cornea, in front of the head of the pterygium known as Fuch’s spots or islets of vogt also called cap of pterygium Regressive pterygium – thin, atrophic, attenuated with very little vascularity. There is no cap, but stocker’s line may be seen sometimes, just anterior to head of pterygium. Ultimately it becomes membranous but never disappears.

11. Complications Cystic degeneration and infection are infrequent Neoplastic change to epithelioma , fibrosarcoma or malignant melanoma may occur rarely

12. Differential diagnosis Pseudopterygium It is a fold of bulbar conjunctiva attached to the cornea. It is formed as a response to an acute inflammatory episode such as chemical burn, marginal corneal ulcer corneal trauma and cicatrizing conjuctivitis . It results due to adhesions of chemosed bulbar conjunctiva with the peripheral de- epithelialised corneal surface

13. Treatment Medical treatment of not much use Tear substitutes in small regressive pterygium for dry eye symptom Topical steroids for associated inflammation Protection from UV rays with sunglasses decreases the growth stimulus Surgical excision is the only satisfactory treatment which may be indicated for Cosmetic disfigurement Visual impairment Continued progression Diplopia Note: once pterygium has encroached pupillary area, wait till it crosses on the other side

14. Surgical technique of pterygium excision

15. Recurrence of the pterygium Recurrence after surgical excision is common (30-50%). However it can be reduced by: Surgical excision with free conjunctival limbal autograph (CLAU) take from the same eye or the other eye is presently the preferred technique Surgical excision with amniotic membrane graft and mitomycin – C (MMC) (0.02%) application may be required in recurrent pterygium or when dealing with a large pterygium Surgical excision with lamellar keratectomy and lamellar keratoplasty may be required in deeply infiltrating recurrent recalcitrant pterygia Old methods – transplantation of pterygium in lower fornix ( McRaynold’s operation) and post operative use of beta irradiations

16. Thank you