A person suffered an injury in the right eye with a tennis ball. Following which he developed pain and on examination of fundus a red spot is seen at the macula. What is the most probable diagnosis?

This patient has developed Berlins edema following injury to the eye. This is caused by a pressure wave which pass into the posterior pole of the eye following blunt eye trauma. In this condition retina develops a grey white colour seen mainly in the outer retina which may extend to the macula. If it involves the macula, it results in cherry red spot seen at the fovea. This is because fovea is very thin and it reflects the red colour of underlying normal choroid. Other causes of cherry red spot: Tay-Sachs disease, Niemann- Pick disease, generalized GM1, gangliosidosis, Farber's lipogranulomatosis, infantile Gaucher's disease, metachromatic leukodystrophy and sialidosis types 1 and 2.