Reducing confounding effects of cataract on glaucoma monitoring

The authors developed a method of measuring visual field components that can help reduce the confounding effects of cataract progression and extraction on measured perimetric progression in patients with coexisting glaucoma and cataract.

This retrospective study included 68 patients (85 eyes) with open-angle glaucoma who underwent cataract extraction and had a total of five or more reliable visual field measurements before and after surgery.

The researchers used pointwise exponential regression to perform trend analysis on thresholds at visual field test locations before and after cataract surgery. They ranked the visual field locations according to their decay rate and divided them into slow and fast decay rate groups.

They found a significant decrease in mean deviation and in the mean slow component rate after cataract surgery compared with before surgery. However, there was no significant difference in the fast component mean rate per year before and after surgery.

They conclude that cataract progression seems to be the main determinant for the slow visual field rate component and does not change the fast visual field rate component.

They note that the results may not apply to patients with more advanced glaucomatous damage since all the subjects had mild to moderate glaucoma.