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Introduction:

Corneal neovascularization = growth of vessel toward central cornea, occuring from limbal vascular plexus.

Treatment:

Topical administration of steroids and non-steroid anti-inflammatory drugs are first-line treatment for individuals with corneal neovascularization. The administration of steroids can increase the risk of infection, glaucoma, cataracts, herpes simplex recurrence. The anti-inflammatory drugs, however, increase the risk of corneal ulceration and melting.

Vascular endothelial growth factor (VEGF) plays an important role in vasculogenesis and pathologic neovascularization associated with eye disease. A potential treatment for corneal neovasculariation is to inhibit VEGF activity by competing the binding of VEGF with specific neutralizing anti-VEGF antibody. Anti-VEGF antibodies have shown to reduce corneal neovascularization. VEGF inhibitors include pegatanib sodium, ranibizumab, and off-label bevacizumab are currently used for treatment of various retinal disease. Topical and/or subconjunctival administration of bevaicizumab or ranibizumab have demonstrated short-term safety and efficacy, however long term effects have not been documented. Studies have shown that topical, subconjunctival, or intraocular application of bevacizumab have exhibited in partial reduction of corneal neovascularization and improving corneal transparency, followed by corneal alkali burn injury by regenerating the basement membrane. Anti-VEGF therapy is currently an experimental treatment.

If the cornea is inflamed via corneal neovascularization, the suppression of enzymes can block corneal neovascularization by compromising with corneal structural integrity. Corneal neovascularization can be suppressed with a combination of orally adminstration of doxycycline and with topical corticosteroid.

Treatment: Surgical Options

Invasive solutions for corneal neovascularization are reserved when the medical therapies do not provide the desired results.

Invading blood tissues and ablating tissues in the cornea can be obstructed by the use of laser treatments such as Argon and Nd: YAG lasers. Irradiation and/or damages to adjacent tissues caused by the procedure can result in corneal hemorrhage and corneal thinning. Obstruction of the blood vessels can be unsuccessful due to the depth, size, and, high blood flow rate of the vessels. In conjunction, thermal damage from the lasers can trigger inflammatory response which can exaggerate the neovascularization.

An effective treatment is photodynamic therapy, however this treatment has limited clinical acceptance due to high costs and many potential complications involved that is also related to laser ablation. Complications can include irradiation from previously injected photosensitive dye inducing apoptosis and necrosis of the endothelium and basement membrane.

Diathermy and cautery is a treatment where a electrolysis needle is inserted into the feeder vessels in the limbus. The vessels are obstructed by a coagulating current through the use of unipolar diathermy unit or by thermal cautery.