Abstract
Purpose:
Postoperative refractive outcome is important to successful cataract surgery. This measurement can be compared to a predicted refractive outcome calculated preoperatively; the difference between these two values gives the prediction error. The relationship between glaucoma surgeries and successful outcomes following cataract extraction with intraocular lens (IOL) placement has been well studied. Despite such investigations few, if any, reports have compared the refractive outcome of glaucoma patients to patients who are glaucoma suspects and patients without glaucoma. This study aims to analyze prediction errors in these three populations in an effort to determine whether differences exist. It also examines the effect of glaucoma drops on prediction error.
Methods:
This retrospective study reviewed charts of 130 eyes from patients who underwent phacoemulsification with IOL implantation. Patients were classified as having glaucoma (56 eyes), being glaucoma suspects (34 eyes), or not having glaucoma (40 eyes). The criteria for glaucoma suspect classification were: IOP >21 mm Hg and/or 0.4 - 0.6 cup/disc ratio without visual field changes and/or asymmetric cupping greater than 0.1. The criterion for glaucoma classification was: 0.6 or greater cup/disc ratio with visual field changes.
Results:
Seventy percent of non-glaucomatous patients, 71% of glaucoma suspect patients, and 54% of glaucoma patients fell within the range of -0.5 to +0.5D from the predicted refractive outcome. There was no statistical difference when comparing patients without glaucoma to patients with glaucoma (P = 0.10) or to glaucoma suspect patients (P=0.96). The mean number of glaucoma medications taken by glaucoma patients falling within the -0.5 to +0.5D range for prediction error compared to those falling outside the same range was 1.70 versus 2.04 (P = 0.13).
Conclusions:
The observed trend suggests that fewer glaucoma patients fall within a tight range around the predicted refractive outcome, though the data are not statistically significant. This trend holds regardless of previous glaucoma surgery. Preservatives in glaucoma eye drops have been shown to affect the corneal surface and, thus, could affect preoperative biometry measurements. However, the observed trend does not seem to be due to differences in the number of eye drops taken by glaucoma patients.
Keywords: 445 cataract •
567 intraocular lens