A retinoschisis is a split in the retina. The photoreceptors remain attached to the underlying retinal pigment epithelium and so there is no retinal detachment.
The inner layers of the retina, though, are split from the outer layers and bulge in towards the centre of the eye. The split in the retina is, in this way, like the split when the layers of a 2-ply tissue are separated.
The commonest type of retinoschisis usually has no effect on vision. It is usually found by chance when a retinal examination is being performed either routinely or for another reason.
Patients with retinoschisis are often referred by other ophthalmologists to vitreoretinal surgeons (surgical retinal specialists) in order to confirm the diagnosis. This is because a retinoschisis can look very much like a retinal detachment and an incorrect diagnosis could be visually significant.
Patients with a retinoschisis have a slightly higher chance of developing a retinal detachment than those without, but it is still only about 1 in 2500.
Nevertheless, if patients with retinoschisis notice new or increased flashes, floaters or a shadow in their vision, they should seek urgent attention just like anyone else. Retinoschisis very rarely causes any problems with vision and generally does not need to be followed up long term. No treatment for the retinoschisis itself is necessary.