Such black spots (scotomas) are not uncommon after head injury and stroke (cerebro-vascular accident). It is possible that your uncle had a stroke and he fell down. Even if he didn t have a stroke and he fell down due to some other reason, it could still cause scotomas. They can be due to local pathology in retina, optic nerve or in problem in nervous system such as a demyelinating disease. Toxic substances and nutritional deficiencies may also can cause them. Many scotomas that occur after stroke and brain injury disappear spontaneously. Since your uncle has had two falls in two days, he needs to be evaluated for falls. Take him to a doctor. Some hospitals have a fall protocol for elderly wherein they use a systematic approach to evaluate the elderly with fall for causes and suggest remedies. I hope this answers your question.