Cone dystrophy

The cone-rod dystrophies ( ZSD ) are a heterogeneous group of inherited eye diseases in which there is at the beginning of the death of the cones in the central retina and then slowly spread into the outer region and on the rods, in contrast to retinitis pigmentosa that develops in the opposite direction introspective. If only the journals concerned, is also spoken of cone dystrophies.

Epidemiology

The frequency of cone-rod dystrophies is about 1:40,000. They occur most commonly to age 20 in appearance, but can also make only noticed later.

Symptoms

The ZSD is a disease in which there is a large loss of visual acuity from the beginning and progresses in the course of variable speed. The name ( cone rod dystrophy ) are already some clues about the disease. When naming the pins are named first, because they are the most affected in this disease. They have their highest density in the center of vision ( macula), so that it can come up with onset of disease to the central visual field defects already that make it to the party concerned impossible to see targeted objects. Since the point of sharpest vision is lost, often result in the movement of the eyes ( nystagmus) or to a misalignment of the eyes (strabismus ). The increasing loss of cones leads to disturbances in adapting to different lighting conditions, thus to an increased sensitivity to glare, which impairs vision in bright light significantly. Also, the recognition of colors is disturbed early. Since the rods are barely affected at the beginning of the disease, seeing in the dawn is still very possible. It was not until later in the middle and outer regions of the retina and thus the rods are affected.

Genetics

The term dystrophy who stands at the end of the name indicates that it is an innate slow progressive destruction of the tissue in this disease. This is caused by mutations in different genes.

The inheritance is autosomal recessive in most cases. But it is also an autosomal dominant or X-linked inheritance. These mutations lead to defects in signal transduction and changes in the structure and the function of the pin. In other cases it may lead to non-formation of the visual purple, or to a disorder of the material transport through the cell membrane. At relatively many ZSD sufferers mutations in the ABCA4 gene were localized, which is responsible for encoding a transport protein in vitamin A metabolism. Therefore, the administration of high-dose vitamin A in these affected not recommended.

Diagnostics

At the beginning of the disease, the fundus is often inconspicuous and have it be visible until later in pigment changes in the macula. In the early stages of the disease often can therefore only be made with an electroretinogram (ERG ) a safe diagnosis. Furthermore, it can result in the formation of dark brown to black metabolic deposits ( bone corpuscles ) and vasoconstriction. A shrinkage (atrophy ) of the RPE and choroid, which are important to the diet of the visual cells determine. This may in the course lead to the center of the retina pigment epithelium which is no longer available. Likewise, with progression of the disease, the strong color of the optic nerve head fade ( Papillenabblassung ), which may indicate a loss of function of the optic nerve.

Treatment approaches

In addition to a healthy lifestyle, it may be that the wearing of solar control glass has a positive influence on the course of the disease. For this, we recommend a cut-off filter glasses, which should not only filter out the UV radiation, but also the blue light component. In addition, they can, according to individual selection, in addition achieve a contrast enhancement.