Free radicals in the aqueous humor of patients with glaucoma

Eiki Oshida, Yukihiro Matsumoto, Kiyomi Arai

¹Department of Ophthalmology, Dokkyo Medical University Koshigaya Hospital, Koshigaya, Saitama, Japan

Purpose: To clarify the presence of oxidative stress in glaucoma and discuss whether free radicals contribute to neovascular glaucoma (NVG) and non-NVG.

Methods: Two patient groups were formed: the NVG group (n = 10) and the non-NVG group (n = 17). Free radicals in aqueous humor were detected by measuring the electron spin resonance (ESR). To identify free radical species, either superoxide dismutase (SOD) or catalase was added to the aqueous humor and compared with aqueous humor in which SOD or catalase was not added.

Results: In the NVG group, free radical waveforms were detected that differed from ascorbate-free radical (AFR) in all cases. Under SOD was added, the characteristic waveforms disappeared and the AFR of a specific waveform appeared. After catalase was added, the waveforms were unchanged. In the non-NVG group, the AFR of specific waveforms were detected in all cases. In 4 cases, the waveforms detected the presence of a trace of superoxide.

Conclusions: In the NVG group, superoxides were detected, suggesting that superoxide scavenging activity was decreased markedly. L-ascorbic acid likely has an antioxidative function in the non-NVG group, suggesting that the aqueous humor in the NVG group was under higher oxidative stress compared with the non-NVG group.

Keywords: oxidative stress, free radicals, glaucoma, ascorbate