Retinoschisis is an eye disease characterized by the abnormal splitting of the retinas 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 (RS1). Classification
Hereditary
X linked juvenile retinoschisis
Familial foveal retinoschisis
Tractional
Exudative
Secondary to Optic disc pit
Degenerative
Typical
Reticular

Degenerative retinoschisis
This type of retinoschisis is very common with a prevalence of up to 7 percent in normal persons. Its cause 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.
Pegasys may refer to:

A brand name of the medication peginterferon alfa-2a
Pegasys, Inc., a Japanese software company that develops the TMPGEnc family of video encoding/editing programs
Pegasus (disambiguation)