Variation of mesopic and photopic spatial resolution in drivers older than 65 years old.

Abstract

In the last century, the proportion of people over the age of 65 years has tripled (Haegerstrom-Portnoy, 1999). According to the US census 2000, persons over 65 years of age comprised 12.4% of the inhabitants of the United States (Schwager, 1999). The spanish National Institute of Statistics estimated this proportion at 16.8% of the population of Spain in 2009, representing a growth rate far higher than shown by other age groups (INE, 2009). Besides this increase, the number of elderly people who continue to drive is set to show a spectacular rise after 2010, due to the incorporation of the "baby-boom" generation and the considerably greater number of women drivers. Added to this social changes and the improved health of the elderly subject are raising the mean age of drivers (Hakkinen, 1984). Spherical and astigmatic defects worsen with age, negatively affecting visual acuity and sensitivity to contrast and glare. Ageing is also associated with diminised myopia, increased hyperopic and tendency towards inverse astigmatism (Adams, 1988). In addition, the retina often undergoes macular degeneration (Morgan, 1986). The physiological alterations of ageing also lead to changes in our sensitivity to light. Enhanced light scattering in the eye gives rise to glare, a decreased pupil diameter with the consequent reduced retinal illumination and to a general decline in visual perception (Van Den Ber, 1986). The present investigation was designed to evaluate the refractive error in vehicle drivers over the age of 65 years and to determine the possible effects of improving their habitual optical correction on visual acuity.