Healthline says the purpose of the retina is to collect light focused from the lens. The retina transduces the light into neural signals and transmits those signals to the brain. The retina sends light information, such as that related to color and light intensity, to the brain via the optic nerve.
Healthline states that the brain receives neural signals from the optic nerve and processes them. Without the retina, a person is blind. A condition called retinal detachment means the retina has moved. The brain is no longer able to receive neural inputs from the optic nerve, and essentially, a person is blind.
WebMD explains retinal detachment as a condition where the retina has somehow been detached from the connective tissue surrounding it. Symptoms of retinal detachment include random flashes of light in the eye, floaters and darkening of the peripheral vision. None of these symptoms are painful, but they need to be immediately evaluated by a doctor. If the condition is caught rapidly, surgery is performed and is usually able to save a person's eyesight.
WebMD also explains that retinal detachment is preventable by getting frequent eye exams, particularly if a person has a family history of the condition, diabetes or nearsightedness.