Retina is the light-sensitive layer of tissue located in the back of the eye. Nutrients and oxygen are richly supplied to it by the retinal blood vessels and an underlying network of blood vessels, called Choroid. The choroid gives the characteristic red color to the retina when examined and also is cause for the red eye defect seen in photographs.
Examining the retina
A retinal examination also called as ophthalmoscopy or funduscopy. It allows the retinal specialist to evaluate the back of your eye, including your retina, optic disk and the underlying layer of blood vessels that nourish the retina (choroid).
For a through retinal examination the pupils must be dilated using eye drops. The eyedrops used for dilation cause your pupils to widen, allowing in more light and giving your doctor a better view of the back of your eye.