A large variety of conditions can affect the vitreous and retina that lie on the back part of the eye that is not readily visible, such as diabetic retinopathy, macular degeneration, retinal detachments or tears, macular holes, retinopathy of prematurity, retinoblastoma, uveitis, eye cancer, flashes and floaters and retinitis pigmentosa.
Structures of the back of the eye
The retina is an extension of the brain. It forms the interior lining of the eye and contains millions of light-sensitive nerve endings (photoreceptor rods and cones). The light rays that enter the eye pass though the cornea, pupil, lens, and vitreous ultimately focusing on the retina. The retina then perceives the light and transmits nerve impulses through the optic nerve to the brain, where a visual image is created.
Vitreous is a clear, gel-like substance that fills the cavity between the lens and the retina.
The macula is an oval area in the center of the retina where light is focused and vision is the sharpest. The macula is composed of retinal photoreceptors (cones and rods). The cones allow us to see in bright light, distinguish color, and discern fine detail. The rods are more sensitive to dim light and allow for night vision. The peripheral retina is made up primarily of rods, which provide peripheral vision both day and night.
In the center of the macula is the fovea, an area smaller than a pinpoint. It is composed entirely of cones. This tiny piece of the retina provides the sharpest vision —- the vision required to read. Everything we look at directly comes into focus at the fovea.
Conditions, diseases and irregularities of the retina and vitreous
The retina and vitreous can be affected by a large variety of conditions, including diabetic retinopathy, retinal vein occlusion, macular degeneration, retinal detachments or tears, macular holes, retinopathy of prematurity, flashes and floaters, retinoblastoma and retinitis pigmentosa.