Clinical evaluation of aqueous outflow system in vivo and correlation with intraocular pressure before and after non-penetrating glaucoma surgery.

PURPOSE: The aim of this study was to evaluate the aqueous outflow system through channelography with fluorescein during non-penetrating glaucoma surgery (canaloplasty or phacocanaloplasty) and find correlations with preoperative and postoperative intraocular pressure (IOP).

METHODS: Thirty-six patients (40 eyes) who had channelography while undergoing non-penetrating glaucoma surgery were included in this prospective study. Several parameters assessed during the channelography included: diffuse and superficial scleral staining, the number of visible superficial connections to collectors, trabecular permeability and number of micro-ruptures of the trabecular meshwork. IOP, the best-corrected visual acuity, the number of glaucoma medications was recorded at 1 day, 7 days, 3 months and 6 months after the operation.

RESULTS: The change in IOP at 6 months from baseline significantly correlated with the number of visible superficial connections to collectors (r = 0.4, p = 0.021). Eyes with canaloplasty showed a mean baseline IOP of 19.4 (4.9) mmHg and mean glaucoma medication usage of 2.9 (1.0), which decreased to 13.2 (3.1) mmHg with 0.3 (0.8) medications, respectively, at 6 months postoperatively (p < 0.001). Eyes with phacocanaloplasty surgery showed a mean baseline IOP of 28.2 (9.6) mmHg with 2.6 (0.9) mean drugs, which decreased to IOP of 12.8 (3.4) mmHg with 0.5 (0.8) medications at 6 months (p < 0.001).

CONCLUSION: A larger number of defined visible superficial connections to collectors after injection of fluorescein into SC is related to a more pronounced IOP decrease after non-penetrating glaucoma surgery.