By Scott K. Schultz, MD
While interest in the IOP-lowering effect of cataract surgery in glaucoma patients is growing, less is known about the overall visual outcomes and complications of cataract surgery in glaucoma patients. This retrospective study finds that glaucoma patients are at higher risk for complications and show weaker visual improvement. Still, these patients experience significant visual improvement and improved quality of life.
There has been a lot of data published recently about the benefit of cataract surgery in glaucoma patients, but this study helps fill-in the picture. Cataract surgery isn't necessarily easy in these patients. Surgeons need to be aware of the risks and be prepared for the other potential outcomes.
Using the Veterans Affairs Ophthalmic Surgery Outcomes database, investigators compared cataract surgery outcomes between 608 glaucoma patients and 4,306 patients without glaucoma. The authors found that glaucoma patients had a higher risk of posterior capsular tear with vitrectomy (OR 1.8, P=0.03) and sulcus IOL placement (OR 1.65, P=0.03). Postop complications included lingering inflammation (OR 1.73, P<0.0001), IOP >25 after 1 week (OR 2.96, P=0.003) and additional surgery within 30 days (OR 1.92, P=0.03).
Cataract surgery significantly improved visual outcomes in both patient groups (P<0.0001), but glaucoma patients had more modest improvements in best-corrected visual acuity (BCVA) and the visual function questionnaire. Fewer glaucoma patients achieved 20/40 or better BCVA compared to controls (89.6% vs. 94.1%, P=0.003).
The authors believe the disparity in outcomes is linked to factors commonly found in glaucoma patients, such as increased prevalence of small pupils, history of prior intraocular surgery, older age, increased density of the cataract at time of surgery and worse pre-operative BCVA. Additionally, glaucoma seemed to be an independent risk factor for inflammation 30 days after surgery, even after taking into account factors such as pseudoexfoliation, previous surgery, use of pupil expansion devices, alpha blockers, anterior chamber depth, iris trauma, iris prolapse, age and small pupil. Interestingly, the glaucoma group had lower rates of iris prolapse and trauma, possibly due to the higher rate of pupil expansion devices used in this group.
The major shortcomings of this study include the inability to collect additional information about the patients before and after surgery, a varied glaucoma history and a relatively short follow-up of 1 month. Further investigation could reveal useful information about these patients and improve pre-operative patient education and counseling to set expectations.