Bilateral inferior dislocation of lens is seen in ?

Ans. is `b' i.e., Homocystinuria Ectopia lentis Ectopia lentis is defined as displacement or malposition of the crystalline lens of the eye. The lens is considered dislocated (luxated) when it lies completely outside the lens patellar fossa. The lens is described as subluxated when it is paially displaced but contained within the lens space.