Retinitis pigmentosa

Introduction

Retinitis pigmentosa is an umbrella term for a group of diseases of the eye which in their course lead to destruction of the retina (retina). The retina is, so to speak, the visual layer of our eye, the destruction of which leads to loss of vision or blindness. The term “retinitis” is rather misleading, since it is not an inflammation of the retina.

The correct term would be “retinopathy”, which however has not been able to establish itself in everyday medical life. The word “pigmentosa” refers to the pigment deposits on the retina, which are typical for this disease and appear as small dots in the ophthalmological examination. In Germany, about 30,000 to 40,000 people suffer from one of the various forms of retinitis pigmentosa. Since retinitis pigmentosa is unfortunately not curable at present, it is one of the most common causes of blindness, usually already in middle adulthood.

Function of the retina

To understand the disease retinitis pigmentosa, it helps to understand the basic structure and functioning of the eye. The human retina is the light-sensitive layer of the eye. With the help of the rods and cones (light receptors) of which it is composed, the incoming light stimuli can be coded into electrical signals and then transmitted via further nerve tracts to the brain, which then processes the incoming information into the actual image.

However, the light receptors are not identical everywhere in the eye. The rods, which are located more in the periphery, i.e. further out in the field of vision, are important for vision at night and at twilight and can therefore perfectly resolve light-dark contrasts, but are not as good as the cones in their sharpness. The cones, on the other hand, which are mainly located centrally in the retina, are used fully during the day.

With the cones we perceive the colors surrounding us and can see things sharply in the center of the field of view. If we take the field of view of both eyes together, we get an angle of about 180°. Thus, the anatomical and functional structure of our eyes enables us to perceive our surroundings in a “panoramic view”.

However, we can only see them sharply in the focus of our field of vision, the area where the incoming image from the left and the right overlap. Here, we can see even small details in sharp focus, whereas further out (i.e., further peripherally), we tend to use the areas for unconscious orientation. If our eyes are fully functional, it is no problem for us to simultaneously perceive the surroundings, e.g. an approaching car, when we look at a specific, more distant object such as a street sign.