الفهرس 
IntroductionOnly 14 pages are availabe for public view
 |  | from | 165 |  |  |
| | | from | 165 | | |
Abstract
Pterygium is a common kertocojunctival degerneratival lesion in tropical and subtropical regions. Egypt is considered one of the areas in which pterygium is prevalent.
The exact aetiology of the pterygium is not known but many theories have been put down to explain the aetiology of the pterygium like the neoplastic theory, Ultra-violet light theory and tear abnormality theory, immunological theory, mechanical theory and the hereditary theory. The Ultra-Violet light theory is the most accepted one because of the prevalence of the pterygium in the tropical areas. It occurs more to people who work outdoors rather than indoors.
As regards the pathology of the pterygium the earliest changes occurring in the cornea are the appearance of small vesicles at the point where the corneal nerves pierce Bowman’s membrane. At these points Bowman’s membrane becomes destroyed and the superficial corneal lamellae degenerate. The developed pterygium is covered by conjunctival epithelium.