In the given condition, cause of defective vision is
Pterygium: - Definition:- A degenerative condition of the subconjunctival tissue which proliferates as vascularised granulation tissue to invade the cornea . Pathogenesis:- * Elastotic degeneration of the subconjunctival tissue with Fibrovascular proliferation . * Destruction of epithelium & Bowman's layer by advancing fibrovascular tissue resulting in corneal scarring. Cause Of Defective Vision In Pterygium:- * Fibrovascular tissue contracts --> flattening of the cornea in the horizontal axis --> ASTIGMATISM {WITH THE RULE ASTIGMATISM } * Obscuring the pupillary region or the Visual axis. Types Of Pterygium:- Depending upon the growth * STOCKER'S LINE:- seen in atrophic pterygium. Iron deposition in front of the head in the corneal epithelium. Ref:- Parson's Diseases of the eye 22nd edition; pg num:- 184
Astigmatism
Hypermetropia
Visual axis is obscured
Diplopia
Cornea and sclera