What is Retinitis Pigmentosa?

RP is a deformation in the receptors of the retina of the eye. It is a purely hereditary disease. The illness manifests itself by a progressive loss of the visual field, usually beginning during childhood. Bad vision during the night is a first sign and the illness is often called for this “Night Blindness”. Eventually in the course of a lifetime RP can lead to full blindness.

Terminology
RP explained
Evolution of RP

Terminology
In medical circles in Cuba the term "Retinosis Pigmentaria" is used. The illness clearly affects the functioning of the photoricipients and the pigmental epithelium. For this the word “pigmentaria”.
It is a deformation of the retina. For this “retinosis”. Often it is called “Retinitis Pigmentaria” but as it is not an inflammation of the retina, this term is not entirely correct.
"Night Blindness" is a common way of calling the illness as bad vision during the night is a sign in the early stages of the disease. But patients also suffer bad vision when the illumination around them suddenly changes.
"Tunnel Vision" is another name. In an advanced stage of the disease patients only see through a small tunnel and loose their peripheral view.
"Usher Syndrome" is a combination of RP with with deafness. The deafness can be from birth or gradually grow during lifetime. The RP is additional to the hearing problems and follows its normal pattern of growing to blindness during lifetime.

human eye RP explained
RP is a deformation of the ability of the retina to perceive light. Receptors of light (so called photoreceptors cells) in the retina consist of cones and rods. Cones are cells located in the centre of the retina. They take care of transmitting color and details of what you see. Rods are cells located around the centre of the retina. They take care of keeping vision in shade or darkness. They also form the peripheral vision. The cones and rods become deficient and the patient starts having problems to see well in shade or darkness. In an advanced stage the patient only sees the centre of his visual field. He or she sees like through a tunnel with no peripheral vision. In a final stage there is a complete loss of vision.
It can also be a deformation of the retinal pigment epithelium. This is a cell layer of the retina that nourishes its visual cells. RP can also be caused by a deformation of the epithelium or by a combination of deformations in the cones, rods and epithelium.
The deficiency of the cells consists in the fact that the blood doesn't circulate well anymore through the cells. The cells become stale and die out.

Evolution of RP
Most patients are born with normal visual capacities. The disease manifests itself progressively during lifetime. This is no strict rule about this but most patients start feeling difficulties during childhood. The loss of sight is gradual and can take decades. Patients can become completely blind or can maintain some visual capacities at an advanced age. In some cases the progression of the disease just stops at a certain age, but it almoast never returns.