Effective injection
Bevacizumab and fine needle diathermy in paediatric corneal neovascularisation shows similar response to that in adult patients
Roibeard O’hEineachain
Published: Saturday, April 1, 2017
The cornea usually remains avascular due to the delicate balance between angiogenic and anti-angiogenic factorsDELICATE BALANCE Dr Elalfy noted that the cornea usually remains avascular due to the delicate balance between angiogenic and anti-angiogenic factors. The most frequent cause of vascularisation is hypoxia and inflammation. Angiogenic factors are released in the cornea by epithelial and endothelial cells, keratocytes, and by the new corneal vessels themselves. That in turn leads to enzymatic degradation of basement membrane of perilimbal vessels, which causes vascular endothelial cells to migrate and proliferate to form new vessels. He added that corneal vascularisation can arise from the limbus, the conjunctiva and the iris, and always travels through preformed planes where they exist. They preferentially travel along planes created by corneal incisions and principally follow the depth of the inciting pathology. The network of corneal vessels is always best established at the site of the inciting pathology, where they tend to persist as a vascular complex, fed by one or more pairs of efferent and afferent vessels. Dua’s classification system describes five separate stages of corneal vascularisation: active young, active old, partially regressed, mature, and regressed. In active young vessels, there are freshly formed bright red vessels with minimal fibrous tissue sheathing. There is also a well-defined arborising network of fine capillaries, with leakage and oedema evident in the surrounding stroma. In active old neovascularisation, progression has ceased but consolidation continues, although the vessels appear less bright. Partially regressed vessels have slow circulation and are less gorged with blood. Mature vessels are relatively large, with minimal arborisation, regressed or absent capillary networks, and persist in scar tissue or stroma after the pathology has healed. Regressed cases have ghost vessels in the stroma, and no corneal oedema. Dr Elalfy noted that their study indicated that, in common with adult patients, paediatric eyes with early disease have the best response to anti-VEGF injections, while those with chronic inflammation are less responsive because of the ongoing pathology. In mature neovascularisations, the pathology is less affected by injection of anti-VEGF and best results are achieved with adjunctive fine needle diathermy occlusion. “Larger sample sizes with longer follow-up are needed to determine the long-term safety and efficacy of these agents in paediatric patients, the best dosing frequency intervals and the best route of administration,” he added. Mohamed Elalfy: m.s.elalfy@gmail.com
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