The inner layer of the eye is the retina and it contains three layers of cells namely ganglionic cell which is innermost, bipolar cells is the middle layer and photoreceptor cells are the outermost layer.

A circular field of approximately 6 mm around the fovea is considered the central retina while beyond this is peripheral retina stretching to the ora Serrata, 21 mm from the center of the retina (fovea). The total retina is a circular disc of between 30 and 40 mm in diameter.