A 32 year old woman had progressive decrease in vision over 3 years. She is now diagnosed as almost blind. What would be the mechanism?

The key is C. Retinopathy. [Cataract is unlikely at this age. Uveitis and iritis doesn’t have such degree of vision loss and iritis and anterior uveitis have pain, redness and photophobia. Open angle glaucoma mostly occurs after the age of 50yrs. Answer should be retinopathy (example retinitis pigmentosa)].