Hi! I appreciate your concerns for the safety of Penegra. Incomplete data like age, presence of any other problem like diabetes, high BP, or heart disease, etc. The vision changes are due to the side effect of Penegra. In addition to causing low BP, irregular heart beats, dizziness, the other less common but serious side effects include vision abnormalities, sudden decreased vision including permanent blindness in one or both the eyes may occur. You have a slightly greater chance of developing Non-Arteritic Anterior Ischemic Optic Neuropathy if you have heart disease, diabetes, high cholesterol, certain other eye problems. I advise you to stop taking Penegra IMMEDIATELY and get medical help right away. You need to be properly examined by an ophthalmologist first then a physician or endocrinologist for proper treatment of ED. Hope the suggestion given above could be useful in getting the effective but safer treatment of ED with ophthalmic evaluation. Take care. A feed back is appreciated.