An in vivo confocal microscopy study and high frequency ultrasound analysis of filtering bleb functionality

Abstract

Abstract Purpose To evaluate in vivo confocal microscopy (IVCM) analysis and high frequency ultrasounds (US) assessment in the follow‐up of filtering blebs. Methods We retrospectively evaluated 38 filtering blebs (29 patients) which underwent filtering surgery for glaucoma with a mean follow‐up time of 16.4 ± 8.4 months. Examination included IVCM and high frequency US. Filtering blebs were classified in 3 functional clinical groups according to the final intra ocular pressure (IOP): target IOP reached without medication (group 1), target IOP reached with medication (group 2) and target IOP not reached despite medication (group 3). Results Our results showed that failed blebs (group 3) present a low density of microcysts (p=0,0035). Microcysts density was correlated negatively to final IOP (r2=0,23 with p=0,002). We also noticed that eyes with a low microcyst density had been treated with more preserved drops per day prior to the surgery (r²=0,12, p=0,04).This point out the negative influence of preservatives on the conjunctiva creating ocular surface damage and modifying its healing process after filtering surgery. Moreover, IVCM examination did not find any relevant differences between ultrasound groups. In clinically efficient blebs we established a panel of microscopic criteria which could define a higher failure risk group not detected by clinical examination or US imaging. Conclusion IVCM enables a precise imaging of filtering blebs at a microscopic level. It brings a panel of valuable criteria for the detection of microscopic signs associated with failed and fibrosed blebs, or with higher failure risk group.