Objective Evaluation of Functionality of Filtering Bleb Based on Polarization-Sensitive Optical Coherence Tomography

PURPOSE. The fibrosis score is a new diagnostic score that we have developed to evaluate the function of bleb structures after glaucoma filtration surgery using polarization-sensitive optical coherence tomography (PS-OCT). This study aims to assess the efficacy of the fibrosis score in discriminating nonfunctional from the functional blebs. METHODS. A total of 20 patients who had undergone glaucoma filtration surgery were imaged at different time periods after surgery using PS-OCT. Birefringence tomography of blebs was obtained from PS-OCT, and the fibrosis score was computed for each patient. The fibrosis score is defined as the area of occupation of high birefringence area in the conjunctiva. The blebs were classified as functional or nonfunctional according to the IOP and the application of medication. The power of the fibrosis score to discriminate nonfunctional blebs from functional blebs was evaluated. RESULTS. The difference in the mean fibrosis score between the functional and nonfunctional bleb group was statistically significant. The fibrosis score showed good ability to discriminate nonfunctional from functional blebs. The area under the receiver operating characteristic curve was 0.82. The best combination of the sensitivity and specificity was 67% and 100%, respectively, for classifying nonfunctional cases. CONCLUSIONS. The fibrosis score showed a high ability to discriminate nonfunctional from functional blebs. Polarization-sensitive OCT is a noninvasive technique that provides not only the fibrosis score but also standard structural tomography. It can be a comprehensive tool for longitudinal evaluation after filtration surgery for glaucoma.