ABOUT STROKES: A stroke is a type of cardiovascular disease that affects the arteries leading to and from the brain. When one of these becomes blocked or bursts, blood and oxygen can't get to that part of the brain and it begins to die. Strokes can cause paralysis, affect language and vision, and lead to memory loss. Strokes kill nearly 163,000 people every year; they are the third leading cause of death, behind heart disease and cancer.
ABOUT THE RETINA: We can see because light reflects off objects in our surroundings and enters the eye through the pupil. The light is then focused and inverted by the cornea and the lens, and projected onto the back of the eye. There we find the retina, which is lined with a series of photoreceptors that convert the light signal into a neural signal. Ganglion cells then transmit those signals to the brain via the optic nerve.