NOV 14, 2012
This analysis of data from the Ocular Hypertension Treatment Study (OHTS) found that cataract surgery with IOL implantation results in a sustained decrease in IOP in patients with ocular hypertension.
The authors compared results from 42 OHTS participants (63 eyes) who had cataract surgery in at least one eye with a control group (743 eyes) that did not undergo cataract surgery.
IOP decreased by an average of 16.5 percent (4.0 mmHg) in the cataract surgery group. This effect was sustained for at least one year, but diminished over the next two years, although it was still lower than preoperative IOP at 36 months. In the control group, IOP decreased only slightly. Those with a higher preop IOP experienced the largest percentage drop in postoperative IOP.
The authors write that the exact mechanism of IOP lowering after cataract surgery is unknown. One explanation is that cataract surgery with lens implantation may increase mechanical tension on the zonule through the? widening of trabecular spaces and decreased outflow resistance.
They urge caution when extrapolating these findings to eyes with lower IOP, higher IOP, and glaucoma. Likewise, they advise against using these results to recommend a particular treatment for ocular hypertension because the participants were not randomized to surgery.
The authors write that they also do not know whether the investigators started IOP medications because these eyes reached a protocol-derived treatment threshold (35 mmHg), developed glaucoma, or needed lower IOP for other reasons. Therefore, they can only state that it decreases IOP but not whether cataract surgery decreases the risk of developing glaucoma in patients with ocular hypertension.