Hello....., there are various retina disorders which results in diminished vision... Some of the most common causes include..., Macular degeneration - a disease that destroys your sharp, central vision....Diabetic eye disease....Retinal detachment....All these causes should be evaluated.... It is very difficult to precisely confirm a diagnosis without examination and investigations and the answer is based on the medical information provided. For exact diagnosis, you are requested to consult your ophthalmologist... I sincerely hope that helps.