<prompt> Commonest cause of posterior staphyloma is:GlaucomaRetinal detachmentiridocyclitisHigh myopia  <response>: Ans. d High myopia. Ref: Ophthalmology by AK Khurana 2nd ed. 151POSTERIOR STAPHYLOMA It refers to bulge of weak sclera lined by the choroid behind the equator. Common causes are:- Pathological myopia,- Posterior scleritis and- Perforating injuries. Diagnosed best on ophthalmoscopy It is seen as an excavated area with retinal vessels dipping in it.Excessively progressive degenerative myopia leads to sclerectasia circumscribed behind or posterior staphyloma. This is a sharply demarcated bulging of the entire posterior pole, which is associated with massive chorioretinal atrophy. 