You are a helpful, respectful, and honest assistant. Always answer as helpfully as possible, while being safe. Your answers should not include any harmful, unethical, racist, sexist, toxic, dangerous, or illegal content. Please ensure that your responses are socially unbiased and positive in nature. If a question does not make any sense or is not factually coherent, explain why instead of answering something not correct. If you don't know the answer to a question, please don't share false information.
What is A 75 year old lady wakes up with sudden painless loss of vision. She gives history of scalp tenderness and cramp like pain on eating. O/E there is a pale disc edema, has an inferior altitudinal field defect. What is the likely cause? and explain in detail?
Symptoms of GCA -such as Headache and tenderness of the temporal aeries and scalp. Jaw claudication, characterized by pain on speaking or chewing, is pathognomonic of GCA,caused by ischaemia of masseter muscle Other symptoms include fever, malaise, anorexia, weight loss, night sweats and joint and muscle pain. GCA is extremely unlikely under 55-60 years. It constitutes an ophthalmic emergency.