Short wavelength sensitive cone acuity: individual differences and clinical use

Acuity of the short wavelength sensitive (SWS) cone pathways was evaluated in 195 observers ages 5-72. A rapid staircase procedure gave comparable results to a longer frequency-of-seeing procedure. Large and reliable individual differences were found among normal observers. Interindividual variability could not be accounted for by differences in density of prereceptoral filters, differences in sensitivity of the SWS cones, or effects of the macular SWS cone-free region, but could be accounted for in part by differences in the accommodative state. Therefore it is important to control the accommodative state in younger observers. SWS cone acuity can be measured reliably and rapidly in a clinical environment and provides a complement to increment threshold measures of the SWS cone pathways.