Colour vision thresholds versus age

Background It is difficult to quantify thresholds in most colour vision tes ts, and this is especially the case for tritan hues, where a strong age-rel ated increase of threshold has been reported. With the development of compu ter-graphic methods it is possible to remove brightness clues caused by len s absorption. This study attempts to give normative values for colour contr ast thresholds and assess the age related changes therein. Patients and methods 115 patients aged between 6 & 71 years were tested for central and peripheral colour contrast sensitivity. No patient had any sys temic or eye disease. As a preliminary, heterochromatic flicker balance bet ween the luminosities of the R and G and B and G phosphors was established, so that all colours subsequently generated were isoluminant for the person tested. Then, using a modified binary search technique, colour contrast th resholds were established using both 2 degree optotypes, for central vision , and a ring, 12.5 degrees in radius for peripheral vision. In the latter c ase, the observer had to name the position of the missing quadrant in the r ing. Stimuli were presented for 200 msec at 1 Hz. Colours were modulated on protan, deutan or tritan colour axis. Results No correlation between age and central colour vision thresholds was observed. By contrast a significant but only minor increase of peripheral colour vision threshold was observed for the peripheral protan and tritan a xis. Discussion The present system removes luminance clues from colour vision te sts and permits both central and peripheral retina to be tested. The result s are simple in that the influence of age can be neglected. The variability of threshold results is small, and it is easy to detect the relatively lar ge changes associated with disease. Since high-quality monitors are standar dised and calibrated, providing the stimulus parameters described are adher ed to, the results given here for upper limits of normal may be used for ot her similar systems.