2004) or brilliant blue to the macular area. These allow visualisation of the ILM and cortex for peeling and removal with forceps (Uemoto et al. 2004; Kadonosono et al. 2001; Kwok and Lai 2003; Kuhn 2003). Insert long-acting gas such as perfluoropropane.

Note: Retinopexy is not required for myopic macular breaks.

Macular retinoschisis without retinal break has also been treated in this way (Kuhn 2003; Ikuno et al. 2004; Kobayashi and Kishi 2003; Kanda et al. 2003) but may run the risk of creating a foveal hole in some patients. A scleral buckle can be placed to produce a macular plombage to flatten the retina

a

b

RRD

Retinal

Fig. 7.24 Posterior staphyloma in myopic eyes (a) seems to be involved in the mechanism of myopic macular hole retinal detachment. A retinal break in the staphyloma allows the SRF to accumulate (b)

as an alternative to PPV (Baba et al. 2006). Posterior pole buckles have also been used to slow the progression of myopia (Ward et al. 2009).

7.8Retinoschisis-Related Retinal Detachment

7.8.1Clinical Features

The term retinoschisis refers to a process whereby fluid accumulates within the retinal neuroepithelium to form a large intraretinal cyst. The cyst cavity has an inner leaf and an outer leaf. Breaks may develop in one or both of these leaves.

a

ERM

b

c

Fig. 7.25 The macula (a) of myopic patient with a macular hole retinal detachment is characterised by a membrane (b) consisting of ILM and vitreous cortex on the macular surface. Once a break appears (c), SRF appears. Peeling this membrane during PPV followed by insertion of gas is enough to achieve successful retinal reattachment of the retina. Traction of the membrane causes the retina to split into a schisis followed by retinal break formation and retinal detachment

Vitreous cortex and ILM

Schitic retina a

Fig. 7.26 A cross section to illustrate the macular retinoschisis possibly created by preretinal membranes in a posterior staphyloma (a) which after retinal hole formation allows retinal detachment (b)

Fig. 7.27 A schitic retina in a myopic staphyloma

Fig. 7.28 Relief of traction on the macular retina is the important process in high myope macular RRD with staphyloma. This is illustrated by this patient who has a persistent macular hole postoperatively but a flat retina because the preretinal vitreous cortex/ILM was removed at surgery allowing the retina to settle into the posterior staphyloma. Operating on patients with myopic foveoschisis can create macular holes like this (see Fig. 7.29)

When fluid passes through an inner leaf break and then an outer leaf break, the outer layer detaches from the pigment epithelium, and the schisis is said to have progressed to a retinal detachment. Occasionally, the fluid in the schisis can enter the subretinal space through the outer leaf break (without an inner leaf break) and very slowly lift the retina giving a slow onset retinal detachment. This can on occasion be treated by laser to the outer leaf breaks causing slow resolution of the retinal detachment.

Retinoschises are classically divided into ‘infantile’ and senile varieties.

7.8.1.1 Infantile Retinoschisis

Infantile retinoschisis is a rare disorder with an ‘X-linked recessive’ mode of inheritance, therefore affecting young males, and must be considered in the differential diagno-

Fig. 7.29 See previous figure

sis when a young boy presents with retinal elevation. A common presentation is vitreous haemorrhage, whilst central vision may be impaired by associated foveal schisis. The inner leaf may be extremely thin because the split in the retina is at the level of the ganglion cells, with large breaks between the blood vessels. Progression to true rhegmatogenous retinal detachment is unusual. Resolution of the macular schisis with restoration of the foveal dip has been described in a few patients after PPV (Ikeda et al. 2008).

Fig. 7.30 This patient had a PPV 10 years ago, but the posterior layer of the vitreoschisis seen in these patients was not removed and has developed into an ERM with traction over the years

Fig. 7.31 A surgeon has performed PPV in a high myope for symptomatic floaters but has missed a vitreoschisis. Consequently, the patient presented with a PVD (the Weiss ring is visible in the image) and RRD a year after the PPV

Fig. 7.32 A thin layer of SRF in a myope with a posterior staphyloma and vitreomacular traction

Fig. 7.33 Injection of triamcinolone during surgery allows easy visualisation of the vitreous. In pathological myopia, this can be used to check for vitreoschisis

7.8.1.2 Senile Retinoschisis

Senile retinoschisis occurs after middle age, is usually bilateral, tends to be located inferotemporally and is frequently discovered during routine examination of the peripheral fundus or even during PPV for other pathologies (when the schisis can be ignored). It is probably commoner in hypermetropes. The split in the retina is in the outer plexiform layer, and, therefore, the inner leaf is relatively thick. The outer leaf of the schisis often has a grey translucency with a mottled pattern. Outer leaf breaks tend to be large with rolled edges and may be pigmented, whilst inner leaf breaks are usually small and round. Most schisis will remain stable, and no intervention is required unless RRD occurs (Byer 1968, 1972, 1976, 1977, 1986, 2002).

7.8.1.3Differentiation of Retinoschisis

from Chronic Rhegmatogenous Retinal

Detachment

Differentiation from chronic retinal detachment (usually atrophic round hole RRD) may be difficult and primarily

relies on experience and the ability of the observer to differentiate detached retina from the thinner inner leaf. Other features help however; see Table 7.4.

A demarcation line, often seen in chronic retinal detachment, may occasionally be seen in retinoschisis where haemorrhage into the cyst has occurred.

Laser photocoagulation applied to the outer wall of a retinoschisis produces a typical blanching retinal burn (in contrast, in a retinal detachment, a poor reaction is seen because only retinal pigment epithelium is present on the outer wall).

7.8.1.4 Retinal Detachment in Retinoschisis

Occasionally, a retinal detachment is seen advancing from the schisis; this advancing edge should consist of the full thickness of the retina and not an increase in the area of split retina, that is, the schisis itself. The appearance of the retina should show a line where the thin inner leaf joins the thicker (and more opaque) full thickness retina. OCT can be used to differentiate the schitic retina from the full thickness elevated retina if the elevation is extending posteriorly.

Two types are described:

•A slowly progressive elevation of the retina at the edge of the shisis thought to be from egress of the fluid in the cyst cavity through the outer leaf breaks and into the subretinal space. There is no communication from the vitreous cavity to the subretinal space because there are no inner

leaf breaks. These can be observed. Lincoff in unpublished work has described resolution of these after 48 h of double eye padding reputably to reduce eye movements followed by laser to the outer breaks to prevent re-accumulation of fluid.

•More commonly, there is a rapid onset RRD in a schisis which has inner and outer leaf breaks. Vitreous cavity fluid can enter the subretinal space producing a more rapid accumulation of SRF. These will require surgery.