Effect of Ginkgo biloba Extract on Visual Field Progression in Normal Tension Glaucoma

Abstract

To evaluate the long-term effect of Ginkgo biloba extract (GBE) on progression of visual field (VF) defects in patients with normal tension glaucoma (NTG). Forty-two eyes of 42 patients with treated NTG who received 80 mg GBE 2 times daily and who had at least 5 VF tests using the Humphrey Visual Field Analyzer for more than a 4-year period before and after GBE treatment were evaluated in this retrospective study. We evaluated the change of progression rate using mean deviation (MD), pattern standard deviation (PSD), and visual field index (VFI) after GBE treatment. The time course of mean total deviation in 10 zones corresponding to the glaucoma hemifield test was analyzed using a linear mixed effects model with unequal random effect variances. The mean follow-up period was 12.3 years. The posttherapeutic intraocular pressures before and after GBE treatment were not significantly different (P=0.509 paired t test). Before GBE treatment, the regression coefficients (RCs) of MD, PSD, and VFI change were -0.619 dB/y, 0.626 dB/y, and -2.153%/y, respectively. After GBE treatment, the RCs of MD, PSD, and VFI change improved significantly to -0.379 dB/y, 0.342 dB/y, and -1.212%/y (P <0.001), respectively. In zone 1, the RC of mean total deviation change was significantly increased after GBE administration (P <0.005). GBE administration slowed the progression of VF damage in patients with NTG, especially in zone 1 corresponding to the superior central field.