Effect of cataract extraction on Visual Field Index in glaucoma

: To determine the effect of cataract on the Visual Field Index (VFI) in glaucoma patients.

: Reliable visual fields (VFs) of 53 patients (53 eyes) with primary glaucoma who underwent phacoemulsification either alone or combined with trabeculectomy were analyzed before and after surgery. All patients had VFs within a period of 15 months before and after surgery. VFI, mean deviation (MD), and pattern standard deviation (PSD) before surgery were compared with those after surgery.

: Median (25th and 75th percentiles) MD after cataract surgery [-10.52 dB (range, -19.25 to -4.86 dB)] was significantly better (P=0.003) than that before surgery [-11.74 dB (range, -20.61 to -7.15 dB)]. Median PSD after surgery [4.76 dB (range, 2.48 to 9.83)] was worse (P=0.01) than that before surgery [3.50 dB (range, 1.93 to 8.20 dB)] when eyes with MD better than -20 dB were considered (41 eyes). VFI after surgery [80% (range, 44% to 94%)] was similar (P=0.92) to that before surgery [77% (range, 37% to 92%)]. MD improved while VFI remained unchanged in both nuclear sclerotic (n=41) and posterior subcapsular cataracts (n=12).

: MD and PSD were significantly affected, whereas VFI was not affected by cataract. VFI may be a more robust measure of VF damage than MD or PSD in glaucomatous eyes with coexisting cataracts.