| ACQUIRED RETINOSCHISIS  SIGNS AND SYMPTOMS
The patient is nearly always asymptomatic. Rarely, the patient reports a sharp visual
field defect corresponding to the area of the retinoschisis. Ophthalmoscopy reveals a
smooth, stationary, bullous elevation of either the inferior-temporal or superior-temporal
retina. The elevation may extend beyond the equator, and may rarely invade the posterior
pole. The dome of the elevation is smooth and translucent. Blood vessels traverse the dome
and cast shadows on the underlying structures. There is no pigmentation line unless a
concurrent retinal detachment exists.
PATHOPHYSIOLOGY
Every eye over the age of eight years manifests peripheral cystic changes in the inner
nuclear and outer plexiform layers of the retina. These spaces coalesce to form
interlacing tunnels. If enough cystic spaces coalesce, the retina will form a
retinoschisis, splitting into an inner and outer layer cavity. The superficial retinal
layers comprise the inner layer, while the deeper layers of the retina and RPE represent
the outer layer of the retinoschisis cavity.
There are technically two types of acquired retinoschisis. There is the
typical degenerative retinoschisis, which presents as a shallow elevation of the inner
retinal layers. There is also reticular degenerative retinoschisis, which presents in the
traditional appearance of a bullous elevation.
In all types of acquired retinoschisis, either the inner
layer or the outer layer, or both layers, may develop holes. Should holes develop in the
inner layer of the retinoschisis, then liquid vitreous may flow into the fluid cavity.
This doesn't change the prognosis. If there are outer layer holes as well, then liquid
vitreous could enter the subretinal space and cause a rhegmatogenous retinal detachment.
To this end, retinoschisis with both inner and outer layer holes has the potential to
progress to rhegmatogenous retinal detachment. The risk of progression to rhegmatogenous
retinal detachment in retinoschisis with double layer holes is 0.25 to 1.4 percent. The
risk of detachment in retinoschisis without double layer holes is 0.024 percent. There is
also potential for the splitting of the retina to continue with posterior extension of the
retinoschisis.
MANAGEMENT
The risk of rhegmatogenous retinal detachment occurring in a retinoschisis (even with
double layer holes) is exceedingly low, so there is no treatment beyond routine monitoring
every six to 12 months. If possible, the retinoschisis should be photographed to monitor
for progression. Because retinoschisis results in a sharply demarcated visual field
defect, the stability can be monitored with a threshold visual field of the central 60
degrees.
CLINICAL PEARLS
While retinoschisis has the potential to enlarge and
extend posteriorly and threaten the macula, its progression is extremely slow and may take
months to years in order to threaten vision. Thus, a retinal consult is rarely urgent.
Because the RPE is not disrupted by retinoschisis, the
RPE does not become hyperplastic and a pigment demarcation line will not form. If a
pigment demarcation line is present in a retinoschisis, it should be taken as a sign that
there is a concomitant retinal detachment.
The retinoschisis shows no movement or undulation upon
eye movement or scleral indentation, whereas a retinal detachment does. Furthermore,
scleral indentation will show preservation of the schisis cavity, as opposed to retinal
detachment.
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