Alpha-tocopherol in plasma, red blood cells and lenses with and without cataract.

Abstract

To compare levels of alpha-tocopherol in human lenses with cataract to clear human lenses and to determine associations between levels of alpha-tocopherol in plasma, red blood cells, and human lenses with cataract. Cross-sectional study. Concentrations of alpha-tocopherol were measured by high-performance liquid chromatography in blood and in human lenses with and without cataract. Lenses were obtained during cataract surgery and from a regional eye bank. Peripheral alpha-tocopherol status in patients was assessed as plasma alpha-tocopherol (total and corrected for low-density lipoproteins) and as red blood cell bound alpha-tocopherol. Data (mean +/- standard error of the mean) are expressed as microM alpha-tocopherol/g lens protein, microM alpha-tocopherol/l plasma, microM alpha-tocopherol/g low-density lipoproteins, and microM alpha-tocopherol/T red blood cells. Concentrations of alpha-tocopherol were measured in 27 lenses of cataract patients, 8 cadaver lenses with cataract and in 14 clear cadaver lenses. The concentration of alpha-tocopherol was significantly higher in cataract than in control cadaver lenses (0.49 +/- 0.04 vs 0.35 +/- 0.03, P < .05). The difference between alpha-tocopherol in lenses of cataract patients and control cadaver lenses was even higher (0.7 +/- 0.1 vs 0.35 +/- 0.03, P < .01). No significant correlation was observed between plasma alpha-tocopherol or red blood cell bound alpha-tocopherol and lens alpha-tocopherol in patients. Serum and red blood cell levels of alpha-tocopherol may not reflect the alpha-tocopherol status of the lens itself and therefore may not be clinically relevant markers for cataract risk. Mechanisms leading to increased levels of alpha-tocopherol in cataract lenses need to be explored in future research.