This could conceivably be trauma or anterior uveitis but notice that the rest of the iris is pretty normal. In a cat of this age I’d be worried about a hypertensive episode. What is the other eye like? Here we can see a detached retina suggestive of hypertensive retinopathy. Blood pressure was 220/180mmHg and treatment with amlodipine at 0.625mg/day orally prevented any further haemorrhage and eventually yielded a relatively normal retina in the fellow eye.