Preliminary Study on the Effect of Intrastromal Anti-Vascular Endothelial Growth Factor Injections on Corneal Neovascularization Using Anterior Segment Optical Coherence Tomography Angiography

Abstract

Background Corneal neovascularization, is a serious condition affecting large percentage of the population. Not only does corneal neovascularization decrease vision and cause corneal edema, but also, it is highly associated with graft rejections. Anti-VEGF has been used in many studies to treat corneal neovascularization with promising results. Recently, evaluation of corneal neovascularization using Optical Coherence Tomography Angiography (OCTA) has been explored and has shown to be promising. Objective To evaluate the effect of intrastromal injection of Anti-VEGF using the swept source anterior segment OCTA on corneal neovascularization. Patients and Methods This pilot study was done in a cohort, prospective manner. The study was done on 10 eyes of 10 patients with corneal neovascularization who were planned for keratoplasty or after keratoplasty. Intrastromal injection of Anti-VEGF using a 30 Gauge needle at a concentration of 5 mg/0.2 mL [2.5%] was done for patients involved in this study. OCTA was done 48 hours before injection, 1 week and 1 month after injection. OCTA images were compared to evaluate the effect of Anti-VEGF on corneal neovascularization. Results Compared with the pre-operative period, at 1 week postoperatively, 9 cases have shown decreased corneal neovascularization, with only 1 case that showed no regression and seemed to be unresponsive to the single injection of Anti-VEGF. At 1 month period, 8 cases had increased vascularization (re-vascularized), 1 case had decreased vascularization again (completely disappeared) and 1 case stayed the same with no change. Cases that have revascularized, have not returned back to the original vascularization level. Using OCTA colored, black and white images, we were able to picture blood vessels in 3-D image and detect subtle changes in corneal neovascularization. Using the OCTA cross-sectional images, we were able to estimate the vessels depths. In 6 cases, vessels were located in the posterior 25% of the cornea (Deep), in 2 cases they were located in the anterior 25 % (Superficial) and in 2 cases they were between the anterior 25 % and the posterior 25% (Mid-stromal). Vessel density was not possible to calculate in this study. Conclusion Bevacizumab intrastromal injections seem to be a very effective temporary method in decreasing corneal neovascularization despite the level of neovascularization. Repeated Bevacizumab injections might be needed to eliminate corneal neovascularization completely. Bevacizumab seems to have a peak action at 1 week period and then its effect seems to ware off gradually. OCTA was able to visualize vessels in 3-D image, even under vascularized corneal scars. OCTA was able to recognize subtle changes in corneal neovascularization, that were not visible by slit lamp.