Reti-whatty pigmen-who? Retinitis pigmentosa (RP), almost as complicated to spell as Gnadenhutten, Ohio and as awkward to say as Coxsackie, New York, is an inherited disease of the retina that often results in blindness. The prevalence of this disease sits around 1 in 4000 and though much research is being devoted to a cure or at least a treatment, currently nothing has been found to fully restore sight in RP sufferers.
The vision loss experienced in Retinitis Pigmentosa develops due to a mutation in any one of over 50 genes, which causes the photoreceptors of the retina to slowly die. The retina is the sensory layer of tissue inside the eyeball and is comprised of a number of layers in itself, one of which is a layer of light-sensitive cells known as photoreceptors that detect light entering the eye before sending the signal down a pathway which eventually ends in the brain for interpretation into what we know as “vision.” Two types of photoreceptors exist – rods and cones, named as such because they resemble – wait for it – rods and cones! In simplified terms, rods predominantly populate the periphery of the retina and thus deal with peripheral vision, while cones are found in their highest density at the central retina in the area known as the macula and are responsible for fine detailed central vision. Other differences between rod and cone photoreceptors include the fact that rods function better in dim lighting while vision in bright light relies on cones; cones are able to detect color while rods are more or less color blind.