Prevention of corneal neovascularization: comparison of different doses of subconjunctival bevacizumab with its topical form in experimental rats.

BACKGROUND

To compare the effect of different dosages of subconjunctival bevacizumab with its topical administration on preventing the development of corneal neovascularization (CNV) in a rat model of corneal chemical injury.

METHODS

Neovascularization was induced by pressing a 2-mm diameter alkaline-coated applicator on the central cornea of the right eye of 50 anesthetized male rats. Immediately after cauterization, rats were divided randomly into 5 groups. Groups 1-4 received a subconjunctival injection of 0.02 ml of normal saline (control) or 1, 5 and 25 mg/ml of bevacizumab, respectively. In the fifth group, topical bevacizumab was instilled daily for 7 consecutive days. After 7 days, digital photographs of the cornea were taken and the area of the neovascularized cornea was calculated.

RESULTS

Analysis of digital photographs showed that, compared with the controls, a single subconjunctival injection of at least 0.1 mg of bevacizumab (5 mg/ml) - immediately after corneal cauterization - effectively decreased CNV after 7 days. Injection of 25 mg/ml of bevacizumab in the fourth group increased the avascular area more than twofold, compared with the saline-treated group (32.2% compared with 15%, p < 0.001). This difference between groups 4 and 2 was statistically significant (p = 0.04). Although topical delivery of 25 mg/ml bevacizumab was effective to inhibit CNV (p = 0.004), the results were similar to those of the third group. Qualitative microscopic evaluation of the cornea was compatible with the gross findings, as bevacizumab-treated groups had less intense corneal vessel channels and inflammation.

CONCLUSION

Both subconjunctival and topical bevacizumab can prevent CNV in rats.