Optical Coherence Tomography Angiography Evaluation of Conjunctival Vessels During Filtering Surgery

Abstract

Purpose To evaluate the changes in conjunctival vascularization with optical coherence tomography angiography (OCT-A) before and after filtering surgery and to correlate these results with filtering surgery success. Methods We evaluated 20 blebs of 20 patients after a first-time trabeculectomy. Conjunctival vascularization was quantified using ImageJ software. Eyes were classified into two groups according to the preoperative conjunctival vessel density: hypovascularized conjunctiva (HypoV; 10 eyes) and hypervascularized conjunctiva (HyperV; 10 eyes). The density of intraepithelial microcysts (0 to 3) was also analyzed. Results There were significantly more needling procedures in the HyperV group, with 70% of the eyes undergoing needling during follow-up compared to 20% in the HypoV group ( P = 0.012). In the HyperV group, 50% of the eyes required IOP-lowering eyedrops after surgery, compared to 10% in the HypoV group ( P = 0.029). HypoV showed significantly more intraepithelial microcysts than did HyperV at 1 week (1.1 vs. 0.4, P = 0.0215), 1 month (2.2 vs. 0.4, P = 0.0003), and 6 months postoperatively (2.0 vs. 0.7, P = 0.0068). A statistically significant correlation was found between preoperative conjunctival vascular density and mean IOP at 1 week ( r = 0.483, P = 0.038), 1 month ( r = 0.714, P = 0.001), and 6 months postoperatively ( r = 0.471, P = 0.043). There was no statistically significant correlation between the preoperative conjunctival vascularization density and the eyedrop-year rate ( r = 0.036, P = 0.8704) or the preservative-year rate ( r = 0.1444, P = 0.5107). Conclusions Poor conjunctival vascularization was associated with lower IOP and a higher number of intraepithelial microcysts evaluated with OCT-A. OCT-A provides a simple, noninvasive, and reproducible method to analyze and quantify bleb vessels before and after filtering surgery. Translational Relevance Several studies have demonstrated that highly vascularized blebs might be associated with a higher risk of failure. OCT-A may provide a dye-free, noncontact method for monitoring conjunctival vascularization after filtering surgery.

Confocal Microscopy and Anterior Segment Optical Coherence Tomography Imaging of the Ocular Surface and Bleb Morphology in Medically and Surgically Treated Glaucoma Patients: A Review

“…Similar results were presented by Hayek et al [ 115 ]. They found a significant correlation between preoperative conjunctival vascular density and mean IOP at six months postoperatively.…”

“…Few studies have evaluated the relationship between filtering bleb vascularization at OCT-A and surgical success after glaucoma surgery ( Table 3 ) [ 112 , 113 , 114 , 115 , 116 ].…”

Predictive Value of Bleb Vascularity after Mitomycin C Augmented Trabeculectomy

“…In our study, the peak in bleb vascularity was 1 day after surgery. In contrast, in the study of Hayek et al [19], vascular density peak was observed 1 week after surgery. On the other hand, Yin et al [5] found a peak in vessel density 1 month after trabeculectomy.…”

“…OCT-A cannot differentiate between arterial/venous and lymphatic vessels. Moreover, conjunctival vascular density was much higher on OCT-A scans when compared to slit-lamp images [19].…”

“…The reason of impaired bleb function after this time is due to scarring and tissue remodeling which takes place at the end of the wound healing process [18]. Interestingly, Hayek et al [19] demonstrated that low preoperative conjunctival vessel density on the site of the future filtering bleb was associated with a lower IOP at 6 months. They measured conjunctival vascularization in OCT-A using ImageJ software.…”