Objective: To determine the effect of cataract extraction on intraocular pressure (IOP) of both eyes in patients undergoing sequential cataract extractions.

Methods: Retrospective review of 116 consecutive treatment-naive non-glaucomatous patients who underwent sequential cataract extractions of bilateral eyes. Baseline and postsurgical IOP measurements of eyes after cataract extraction were reviewed. Postsurgical IOP of the first surgical eye was compared with the IOP of the (unoperated) second eye.

Results: Before surgery, there was no significant difference between the mean IOP of both eyes (15.4±2.6 mm Hg vs 15.2±2.5 mm Hg, p=0.22), and good correlation of presurgical IOP in both eyes was observed. After surgery, mean IOP in the first surgical eye decreased to 14.0±3.1 mm Hg at 1 month (p≤0.001). There was sustained and statistically significant (p<0.001) decrease in IOP in that eye for 2 years. Mean decrease in IOP ranged from 1.6 (8.6%) to 2.3 mm Hg (14.0%). In contrast, the IOP in the fellow (non-surgical) eye remained unchanged. Subsequently, cataract surgery to the fellow eye resulted in a decrease in IOP to a level similar to that of the previously operated eye, which was similarly sustained. Presurgical IOP was the only factor affecting the magnitude of decrease in IOP.

Conclusions: There is sustained decrease in IOP after cataract extraction in non-glaucomatous eyes. This decrease is of greater magnitude in eyes with higher presurgical IOP and is not affected by the type of surgery performed. The effect of IOP decrease after surgery is unilateral and does not affect the fellow eye.