This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: AIIMS 2018, Subject name: Ophthalmology
A patient is taking drugs for rheumatoid ahritis and has a history of cataract surgery 1 year back, the patient presented with sudden painless loss of vision, probable diagnosis is? 
Select and explain. 
A. CME, B. Macularhole, C. Chloroquine toxicity, D. Chronic choroiditis
C: Chloroquine toxicity
Answer: C: Chloroquine toxicity 
Explanation: Patient of rheumatoid ahritis are given hydroxychloroquine which cause painless loss of vision due to bull's eye maculopathy characterized by a foveolar island of pigment surrounded by a depigmented zone of RPE atrophy, which is itself encircled by a hyperpigmented ring (A). There is moderate to severe reduction in VA (6/36-6/60). A more substantial macular lesion follows, with widespread RPE atrophy surrounding the fovea (B). Later retinal aerioles may become attenuated, and pigment clumps can form in the peripheral retina.(C)