Secondary Angle-Closure Glaucoma
Douglas J. Rhee
Jamie E. Nicholl
NEOVASCULAR GLAUCOMA
Neovascular glaucoma (NVG) is a secondary closed-angle form of glaucoma. Initially, a fibrovascular membrane grows over the trabecular meshwork. This is an occluded but open angle. Within a short period of time, the fibrovascular membrane contracts, closing the anterior chamber angle. This often leads to a dramatic elevation of intraocular pressure (IOP), usually greater than 40 mm Hg.
Epidemiology and Pathophysiology
• The exact incidence of all NVGs is not known. NVG can occur as the sequela of several different possible conditions, most commonly, ischemic central retinal vein occlusions and proliferative diabetic retinopathy.
• Other predisposing factors include ischemic central retinal arterial occlusions, ocular ischemic syndrome, branch retinal arterial or vein occlusions, chronic uveitis, chronic retinal detachments, and radiation therapy.
• Some of the best estimates of the incidence of NVG come from studies on central retinal vascular occlusions (CRVOs). Approximately one-third of all CRVOs are ischemic. Between 16% and 60%, depending on the extent of capillary nonperfusion, of ischemic CRVOs will develop neovascularization of the iris. Approximately 20% of eyes with proliferative diabetic retinopathy will develop NVG. Approximately 18% of eyes with central retinal arterial occlusions will develop neovascularization of the iris (Fig. 18-1). Eyes with neovascularization of the iris are at high risk of developing NVG.
History
• Patients may be asymptomatic or may complain of pain, red eye, and reduced vision.
Clinical Examination
• Slit lamp: Corneal edema may be present in the anterior chamber from elevated IOP. The anterior chamber is usually deep with some flare. Hyphema and rare white cells may be present. Fine, nonradial vessels are present on the iris (Fig. 18-1).
• Gonioscopy: If the cornea is clear, gonioscopy may show a vascular net over the angle (NVA) in the early stages (Fig. 18-2).
Later, broad peripheral anterior synechiae occluding some or all of the angles may be seen.
Later, broad peripheral anterior synechiae occluding some or all of the angles may be seen.
• Posterior pole: Retinal findings are consistent with the underlying pathology.
Management
• Typically, antiglaucoma medical management is not adequate in controlling the IOP.
• The mainstay of initial treatment is immediate anti-vascular endothelial growth factor (anti-VEGF) therapy. Panretinal photocoagulation (PRP) is often still needed.
• If the patient is diagnosed with ischemic retinal disease before the development of NVG, anti-VEGF treatment should be started at the appearance of neovascularization in the angle or the iris. Patients in whom fibrovascular membrane-mediated angle closure is already present, anti-VEGF should be pursued if there is any residual trabecular meshwork exposed. Regression of the NVA can result in some opening of the angle. Typically, regression of neovascularization of the iris (NVI)/NVA will occur within 24 to 72 hours.
• Surgical intervention, to lower the IOP, may be required if anti-VEGF treatment/PRP fails. As the mechanism is a mechanical closing of the angle, trabecular meshwork bypass procedures are not indicated. Options include trabeculectomy with an antifibrotic agent, a glaucoma drainage implant device, and/or cyclodestructive procedures. Anti-VEGF treatments are a useful adjunct to the aforementioned glaucoma procedures.
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