We compared two methods for assessing changes in the human lens associated with age. The first is a subjective method for quantifying light absorption by the lens. It is useful for determining the functional effect of age-related increases in lens density, especially for short-wavelength light. The second method objectively and rapidly measures the increase in scattered light with increasing lens density. These two methods accurately measured age-related changes and were highly correlated with each other (r = 0.72, P less than 0.001). Both methods were evaluated in a population of normal eyes, eyes with ocular hypertension, and eyes with primary open angle glaucoma. We found ni significant differences among these groups with either method.