Secondary glaucoma following vitreo-retinal surgeries

Vitreoretinal surgeries either in the form of external compression by buckles or by increasing the intraocular volume by tamponades can cause a significant rise in intraocular pressure (IOP), causing glaucoma to be one of the most common consequences of vitreoretinal surgeries despite improved surgical techniques. Identifying the mechanism that causes the raised IOP is crucial as the management of glaucoma can differ accordingly. Intravitreal (IVT) injections in the form of IVT steroids or anti-vascular endothelial growth factor (anti-VEGF) injections can also cause a significant rise in the IOP and effect, especially the glaucomatous eyes, which are already predisposed. Not just the overlapping clinical features make the diagnosis confusing but also associated scarring of the conjunctiva, and the presence of episcleral hardware in some cases due to scleral buckle make the surgical management of glaucoma in these eyes very challenging. In this review, we describe in detail the various mechanisms causing secondary glaucoma post vitreoretinal surgeries with a focus on how to distinguish between them. We also discuss the possible consequences of anti-VEGF agents on IOP, various surgical challenges, and modifications with newer surgical options in the management of this refractory glaucoma.