The change of anterior segment parameters after cataract surgery in normal-tension glaucoma

Abstract

AIM: To investigate the change of anterior chamber angle morphology and intraocular pressure (IOP) reduction after cataract surgery in patients with normal-tension glaucoma (NTG) using swept-source optical coherence tomography (SS-OCT).

METHODS: This prospective, comparative, observational study recruited patients into two groups. Group 1 was the control group including normal subjects except those with cataracts (cataract group, n=67 eyes of 67 patients), and group 2 was NTG group including patients who were diagnosed with NTG and cataracts (n=43 eyes of 43 patients), which were treated with phacoemulsification and intraocular lens implantation. Before surgery, and at postoperative 1 and 6mo, anterior chamber angles were evaluated by SS-OCT under dark conditions using three-dimensional angle analysis scan protocol. Angle opening distance (AOD), angle recess area (ARA), and trabecular-iris surface area (TISA) at four quadrants (temporal, nasal, superior, and inferior) were calculated automatically by SS-OCT, after the observer marked scleral spurs.

RESULTS: A total of 106 patients (54 males and 52 females) were enrolled in the study. Angle parameters, AOD, ARA, and TISA were increased after surgery in both groups. However, changes of angle parameters were only significant in group 2. In group 2, preoperative IOP was 13.2±2.9 mm Hg, and postoperative IOP at 1 and 6mo were 10.5±3.0 and 10.7±2.8 mm Hg, respectively. In group 1, preoperative IOP was 12.4±2.8 mm Hg, and postoperative IOP at 1 and 6mo were 11.6±2.5 and 12.0±2.8 mm Hg, respectively. After cataract surgery, angle parameters changed significantly while IOP significantly reduced and was maintained in group 2 (P<0.001). The changes in angle parameters (ΔAOD500, ΔTISA500 at temporal; ΔAOD500, ΔARA500 at nasal) were linearly correlated with postoperative IOP changes.

CONCLUSION: Cataract surgery may have improved anterior chamber angle parameters and decreased IOP in NTG patients.