IOP lowering with cataract surgery alone, cataract/iStent implantation, and cataract/goniotomy in glaucoma patients

Abstract

Purpose : We compared the changes in intraocular pressure (IOP) induced by cataract surgery alone, cataract surgery/goniotomy (Kahook Dual Blade, New World Medical, Rancho Cucamonga, CA), and cataract surgery/iStent implantation (Glaukos Corp, Laguna Hills, CA) in glaucoma eyes.

Methods : This comparative, retrospective longitudinal cohort study included 162 eyes with cataract surgery alone (n=142 patients), 25 eyes with cataract/iStent implantation (n=24 patients), and 29 cataract/goniotomy eyes (n=23 patients) with 6 month follow-up. We analyzed differences between groups in the change in IOP and number of medications from preoperative to each postoperative timepoint (day 1, week 2 and months 1, 3, and 6), with linear regression and Poisson regression, respectively.

Results : We found no difference in age, gender, preoperative IOP, or preoperative medications (p>.05 for all) between the groups. Diagnoses were primary-open angle 54/216 eyes (25%), normal-tension 10/216 (4.6%), pseudoexfoliation 6/216 (2.7%), and pigmentary 5/216 (2.3%) glaucoma. The control group contained 50/162 (31%) glaucoma patients.
Table 1 shows results for IOP and medication for both groups. The mean preoperative IOP (±SD) for the cataract only, cataract/iStent, and cataract/goniotomy group was 15.47 ± 3.42, 18.72 ± 7.06, and 17.66 ± 5.95, respectively. The IOP of the iStent group was significantly lower than control at Day 1, 3 months and 6 months (p<0.05 for all). The IOP temporarily increased at 2 weeks but this was not significant (p=0.57). The IOP of the goniotomy group was only significantly lower than control at Day 1 postop (p< 0.001). There was no statistically significant reduction at 2 weeks, 3 months or 6 months (p> 0.05 for all).
The reduction in IOP lowering medications did not reach statistical significance when compared to control in any group (p> 0.05 for all).

Conclusions : Among eyes receiving cataract surgery, when compared to control, both goniotomy and iStent lowered the IOP in the immediate postoperative period. Only iStent maintained a statistically significant reduction in IOP at 3- and 6-month follow-up.

This is a 2020 ARVO Annual Meeting abstract.