Definitions

cryopexy

Retinoschisis

Retinoschisis is an eye disease characterized by the abnormal splitting of the retina's neurosensory layers, usually in the outer plexiform layer, resulting in a loss of vision in the corresponding visual field in some rarer forms. More common forms are usually assymptomatic.

Classification

  • Degenerative
    • Typical
    • Reticular
  • Hereditary
    • X linked juvenile retinoschisis
    • Familial foveal retinoschisis
  • Tractional
  • Exudative
    • Secondary to Optic disc pit

Degenerative Retinoschisis

This type of retinoschisis is very common with a prevalence of up to 7 percent in normal persons. It's aetiology is unknown. It can easily be confused with retinal detachment by the non-expert observer and in difficult cases even the expert may have difficulty differentiating the two. Such differentiation is important since retinal detachment almost always requires treatment while retinoschisis never itself requires treatment and leads to retinal detachment (and hence to visual loss) only occasionally. Unfortunately one still sees cases of uncomplicated retinoschisis treated by laser retinopexy or cryopexy in an attempt to stop its progression towards the macula,. Such treatments are not only ineffective but unnecessarily risk complications. There is no documented case in the literature of degenerative retinoschisis itself (as opposed to the occasional situation of retinal detachment complicating retinoschisis) in which the splitting of the retina has progressed through the fovea. There is no clinical utility in differentiating between typical and reticular retinoschisis. Degenerative retinoschisis is not known to be a genetically inherited condition.

Hereditary Retinoschisis

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 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".

Retinoschisis can be caused by an X-linked genetic defect, affecting the vision of men who inherit the disease from their unaffected carrier mothers. The genetic form of this disease usually starts during childhood and is called Juvenile X-linked Retinoschisis. Affected males are usually identified in grade school, but occasionally are identified as young infants.

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.

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. Vision cannot be improved by glasses, as the nerve tissue itself is damaged by these cysts.

Tractional Retinoschisis

This may be present in conditions causing traction on the retina especially at the macula. This may occur in: a The vitreomacular traction syndrome; b Proliferative diabetic retinopathy with vitreoretinal traction; c Atypical cases of impending macular hole.

Exudative Retinoschisis

Retinoschisis involving the central part of the retina secondary to an optic disc pit was erroneously considered to be a serous retinal detachment until correctly described by Lincoff as retinoschisis. Significant visual loss may occur and following a period of observation for spontaneous resolution, treatment with temporal peripapillary laser photocoagulation followed by vitrectomy and gas injection followed by face down positioning is very effective in treating this condition.

References

  • http://www.kellogg.umich.edu/patientcare/conditions/retinoschisis.html
  • http://www.mrcophth.com/retinacases/retinoschisis.html

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