Retinitis pigmentosa (RP) and the retina

The eye is an organ that consists of tissues working together to convert the light reflected off objects in the outside environment to electrical signals that are sent via the optic nerve to the brain. The brain then interprets these impulses and forms a picture that is interpreted as sight.

But like any other part of the complex, finely tuned body - a breakdown at any point along this pathway results in less than perfect vision or in some cases no sight at all.

With retinitis pigmentosa, an inherited retinal degenerative disease, it is the rods and cones of the tissue at the back of the eye that are affected. These cells form part of the retina and contain the light capturing cells necessary for sight. Light passes through the cornea to the pupil, which dilates according to the amount of light in the environment, to the lens, which thickens or thins to bring the object into focus, through the middle of the eye and onto the retina's rods and cones.

While rods are extremely responsive to light and therefore play an important part in night vision, cones are responsible for color (and therefore day vision). The rods are more than ten times as numerous than the cones (120 million to 7 million) and are present everywhere but the fovea - which is cone rich. Cones are scattered throughout the eye.

Retinitis pigmentosa may begin as degeneration of either rods or cones. When the rods stop functioning, the result is difficulties seeing in dim lights and eventual night blindness. As the rods surrounding the fovea degenerate, a person with RP will notice a loss of peripheral vision that may eventually result in so called 'tunnel vision'. When cones cease functioning loss of color vision and decrease in the sharpness of image results. This often causes difficulty in reading.

An ophthalmologist can detect irregularities in the eye's response to light with specialized equipment. If you are experiencing any of these symptoms see a specialist immediately. There are many different types of degenerative retinal disorders and many have similar symptoms.

 

 

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