Surgical treatment of blood vessels an option for some with corneal neovascularization

PITTSBURGH — Surgical options may benefit patients with corneal neovascularization who do not respond to standard therapies, said Deepinder K. Dhaliwal, MD.

She spoke about two surgical modalities for treatment of new corneal vessels here at a symposium on “Angiogenesis and its inhibition” at the University of Pittsburgh Medical Center.

Corneal neovascularization can manifest as surface neovascularization, associated with ocular surface disorders, or as stromal neovascularization resulting from infectious keratitis, Dr. Dhaliwal said. Typically, topical corticosteroids are prescribed, she said, but steroids can induce glaucoma and cataracts. Nonsteroidal anti-inflammatory drugs may be more appropriate because they can inhibit the enzyme cyclooxygenase-2, Dr. Dhaliwal said.

In some cases, anti-angiogenic therapy can be beneficial because it addresses underlying causes of the disorder, she said. The initial causes of the neovascularization must still be addressed, by, for instance, administering antibiotics to clear infections, discontinuing contact lenses, removing sutures after penetrating keratoplasty and administering systemic immunosuppression in cases of ocular cicatricial pemphigoid, she said. If medical therapy fails, surgery may be considered.

One surgical option, photothrombosis, uses a low power argon laser for light activation of a photosensitive dye to produce a localized photochemical thrombosis of vessels. Dr. Dhaliwal described a pilot study in which researchers at the University of Pittsburgh evaluated photothrombosis as a treatment in 14 patients with corneal neovascularization. A blue-green argon laser was applied for a 0.5 sec using a 150 µm to 200 µm spot size.

Patients were typically treated in a series of five sessions. Following treatment, patients reported an improvement in vision, photophobia and general corneal appearance, Dr. Dhaliwal said.

“Objectively, signs of corneal edema, neovascularization and lipid keratopathy were reduced,” she said.

Another surgical option is fine needle diathermy, she said. In this approach, five cutting needles are attached to a 10-0 nylon suture and inserted close to the limbus to the depth of the neovascularization. A diathermy probe set to the lowest setting is then placed in contact with the needles until mild blanching of the corneal stroma occurs. This usually requires no more than 1 second, she said.

The procedure is performed at the operating microscope with the patient under topical anesthesia. The treatment is applied to the entire area of neovascularization. If necessary, re-treatments can be applied after 2 weeks, Dr. Dhaliwal said.

In a small study conducted by researchers in England, patients with active graft rejection from areas of neovascularization improved following treatment with fine needle diathermy, she said.

“These patients had actually failed previous treatment with high dose corticosteroids,” she noted.