Typical peripheral cystoid degeneration is present in virtually all adults. Contiguous with and extending up to 2–3 mm posterior to the ora serrata, the area of degeneration has a bubbly appearance and is best visualized with scleral depression. The cystoid cavities in the outer plexiform layer contain a hyaluronidase-sensitive mucopolysaccharide. The only known complications of typical cystoid degeneration are coalescence and extension of the cavities and progression to typical degenerative retinoschisis.
Reticular peripheral cystoid degeneration is almost always located posterior to and continuous with typical peripheral cystoid degeneration, but it is considerably less common. It has a linear or reticular pattern that corresponds to the retinal vessels and a finely stippled internal surface. The cystoid spaces are in the nerve fiber layer. This condition may progress to reticular degenerative retinoschisis (also known as bullous retinoschisis).
Although degenerative retinoschisis is sometimes subdivided into typical and reticular forms, clinical differentiation is difficult. The complications of posterior extension and progression to retinal detachment are associated with the reticular form. Retinoschisis is bilateral in 50%–80% of affected patients, often occurs in the inferotemporal quadrant, and is commonly associated with hyperopia.
In typical degenerative retinoschisis, the retina splits in the outer plexiform layer. The outer layer is irregular and appears pockmarked on scleral depression. The inner layer is thin and appears clinically as a smooth, oval elevation, usually in the inferotemporal quadrant but sometimes located superotemporally. Occasionally, small, irregular white dots (“snowflakes”) are present; these are footplates of Müller cells and neurons that bridge or formerly bridged the cavity. The retinal vessels may appear sclerotic. In all cases, peripheral cystoid degeneration with a typical “bubbly” appearance can be found anterior to the schisis cavity. The schisis may extend posteriorly to the equator, but complications such as hole formation, retinal detachment, or marked posterior extension are rare. The split in the retina almost never extends as far posteriorly as the macula.
Figure 16-18 Retinoschisis with large, irregular outer-schisis-layer holes (outlined by arrowheads) and yellow dots on the inner surface.
(Courtesy of Colin A. McCannel, MD.)
In reticular degenerative retinoschisis, the splitting occurs in the nerve fiber layer. The very thin inner layer may be markedly elevated. As in typical retinoschisis, the outer layer appears pockmarked and the retinal vessels sclerotic. Posterior extension is more common in reticular than in typical retinoschisis. Approximately 23% of cases have holes in the outer wall that may be large and have rolled edges (Fig 16-18).
Reed D, Garg AJ. Degenerative retinoschisis. In: Schachat AP, Wilkinson CP, Hinton DR, Sadda SR, Wiedemann P, eds. Ryan’s Retina. 6th ed. Philadelphia: Elsevier/Saunders; 2018:chap 100.
Excerpted from BCSC 2020-2021 series: Section 10 - Glaucoma. For more information and to purchase the entire series, please visit https://www.aao.org/bcsc.