Going with the Flow

Having more of an impact in narrow-angle (NA) eyes than open-angle (OA) eyes, cataract surgery can have a reducing effect on intraocular pressure (IOP) in patients, a drop which may be attributed to the post-surgical increase in both Schlemm’s canal (SC) and the anterior chamber angle (ACIA), previous studies have noted.

To further explore IOP reduction in these cases, researchers from Wenzhou Medical University, Zhejiang, China, have examined the relationship between the changes in SC and ACIA in 115 eyes of 92 cataract patients, post-phacoemulsification.

The researchers used swept-source optical coherence tomography (SS-OCT) to evaluate this relationship, then compared the differences in changes between NA and OA eyes. Patients were excluded if they had glaucoma, suffered major intraoperative and postoperative complications, experienced previous intraocular/laser surgery, had conjunctival or corneal abnormalities that could have affected the SS-OCT images, had poor-quality SS-OCT images, or if they’d failed to complete follow-up checks.

In the 89 eyes of the 75 patients that remained in the study, it was confirmed that cataract surgery does help to lower IOP and that Schelmm’s canal, post-cataract surgery, expands. NA patients were found to show greater drainage improvement than OA patients, suggesting that cataract surgery can be more beneficial to this cohort.

Additionally, because the trabecular meshwork and ciliary muscle were also found to be expanded after surgery, this supports the idea that cataract removal has a "chain reaction" effect on the scleral spur and the aqueous humor outflow pathway, also making it easier for the eye to drain excess fluid.