Cataract Surgery and Visual Field Progression in POAG
American Journal of Ophthalmology, May 2019
Comorbid cataract and glaucoma present a clinical challenge, as glaucoma treatment can hasten cataract development, and the presence of cataract causes diffuse visual field (VF) loss. Kim et al. hypothesized that cataract surgery would slow rates of VF decay in patients with primary open-angle glaucoma (POAG), compared with rates during cataract progression. However, they found that despite improvement in intraocular pressure (IOP), VF decay accelerated significantly.
The authors reviewed medical records of patients with POAG who had four or more reliable VFs before and after cataract surgery, which involved placement of an IOL. The operations occurred during a 12-year period. The researchers also looked at a comparison group of pseudophakic eyes that had 10 reliable VFs after surgery. They then used the Glaucoma Rate Index (GRI), a new algorithm, to estimate the rate of change for the entire VF.
Among the 134 study eyes (99 patients; mean age, 66 years), the mean follow-up periods were 6.5 years before and 5.3 years after surgery. All IOP parameters improved after surgery. However, except for patients with previous trabeculectomy, VF indexes (mean ± standard deviation per year) showed worsening rates of decay after cataract surgery versus beforehand.
Higher postoperative peak IOP and worse baseline mean deviation (MD) correlated significantly with faster postoperative peak VF decay. Subgroup analysis showed that VF decay measured by MD, VF index, and GRI was worse in the latter half of the postoperative period, which may relate to the nonlinear natural history of glaucoma.
In addition to concluding that reduced IOP after cataract surgery does not slow VF decay in POAG, the authors suggested that high postoperative peaks in IOP may signal further decline after surgery.
The original article can be found here.