Retinoschisis
Retinoschisis is an eye disease characterized by the abnormal splitting of the retina's neurosensory layers, usually in the outer plexiform layer. Retinoschisis can be divided into degenerative forms which are very common and almost exclusively involve the peripheral retina and hereditary forms which are rare and involve the central retina and sometimes the peripheral retina. The degenerative forms are asymptomatic and involve the peripheral retina only and do not affect the visual acuity. Some rarer forms result in a loss of vision in the corresponding visual field.
Almost all cases are X-linked recessive and caused by a mutation in the retinoschisin gene.
Classification
- Hereditary
- * X linked juvenile retinoschisis
- * Familial foveal retinoschisis
- Tractional
- Exudative
- * Secondary to optic disc pit
- Degenerative
- * Typical
- * Reticular
Degenerative retinoschisis
Hereditary retinoschisis
Hereditary retinoschisis is derived from a defective retinoschisin protein, which is due to an X-linked genetic defect. The genetic form of this disease usually starts during childhood and is called X-linked juvenile retinoschisis or congenital retinoschisis. Affected males are usually identified in grade school, but occasionally are identified as young infants.It is estimated that this much less common form of retinoschisis affects one in 5,000 to 25,000 individuals, primarily young males. Schisis is derived from the Greek word meaning splitting, describing the splitting of the retinal layers from each other. However, schisis is a word fragment, and the term retinoschisis should be used, as should the term iridoschisis when describing splitting of the iris. If the retinoschisis involves the macula, then the high-resolution central area of vision used to view detail is lost, and this is one form of macular disease. Although it might be described by some as a "degeneration", the term macular degeneration should be reserved for the specific disease "age-related macular degeneration".
Very few affected individuals go completely blind from retinoschisis, but some sufferers have very limited reading vision and are "legally blind". Visual acuity can be reduced to less than 20/200 in both eyes. Individuals affected by XLRS are at an increased risk for retinal detachment and eye hemorrhage, among other potential complications.
Retinoschisis causes acuity loss in the center of the visual field through the formation of tiny cysts in the retina, often forming a "spoke-wheel" pattern that can be very subtle. The cysts are usually only detectable by a trained clinician. In some cases vision cannot be improved by glasses, as the nerve tissue itself is damaged by these cysts.
The National Eye Institute of the National Institutes of Health is conducting clinical and genetic studies of X-linked juvenile retinoschisis. This study began in 2003 and as of 2018 is continuing to recruit patients. A better understanding of why and how XLRS develops might lead to improved treatments. Males diagnosed with X-linked juvenile retinoschisis and females who are suspected carriers may be eligible to participate. In addition to giving a medical history and submitting medical records, participants submit a blood sample and the NEI will perform a genetic analysis. There is no cost to participate in this study.