Why does the human visual system age in the way it does?

The tentative observation that the decrease of lenticular glutathione in man and in cattle may be under genetic control is extended to other biological functions which show a systematic reduction with age. Ocular and visual parameters are shown to decline consistently with the view that the human eye has evolved in keeping with other biological functions sustaining a life-span of approximately 120 years. Analysis of the data suggests that presbyopia represents an outlier in the distribution of ocular attributes, and should not be used as a biomarker for ageing.