A 25 year old lady presents with a unilateral cataract. There is no history of trauma, pain, redness of eyes or steroid usage. What is the likely cause?

The best answer would be fuchs heterochromic iridocyclitis Fuchs' 'heterochromic iridocyclitis' is a chronic non-granulomatous type of low grade anterior uveitis typically associated with early cataract formation. It typically occurs unilaterally in middle-aged persons. The disease is characterized by: Heterochromia of iris, Diffuse stromal iris atrophy, (moth-eaten appearance), may cause trans illumination defects, Fine stellate KP's at back of entire cornea, Faint aqueous flare, Absence of posterior synechiae, A fairly common rubeosis iridis, sometimes associated with neovascularisation of the angle of anterior chamber, and Comparatively early development of complicated cataract and secondary glaucoma (usually open angle type) Age related cataract usually occurs after 50 years of age and is thus ruled out. Complicated cataract is unlikely since there is no pain or redness suggesting anterior uveitis. Diabetic cataract is also unlikely since there is no history of diabetes.