Optimized coloured light for enhancing colour discrimination in blurred and cloudy visions

Radsamrong Anukul – Thailand, Chulalongkorn University

Aim: A part of our study on optimized light sources for enhancing colour discrimination of the low vision people is selecting and mixing coloured lights from short, medium and long wavelengths based on colour discrimination. The objective of this part of the study is obtaining the optimized LED channels that can enhance colour discrimination for subjects wearing blurred and cloudy low vision glasses.
Procedure: Four of Munsell patches 5R5/8, 5Y5/8, 5G5/8 and 5B5/8 were measured with a spectroradiometer under 14 channels of the Telelumen-colour tunable LED luminaire. The measured data were used for generating colours and arranged them into 6 main pairs (5R/5Y, 5R/5G, 5R/5B, 5Y/5G, 5Y/5B and 5G/5B) for individual channel. The luminance of individual colour of the main pairs then was generated from 5% to 95% percents with 5% interval and each of generated patch was paired to obtain the highest luminance contrast ratio to the lowest. These pairs were displayed and masked on calibrated Eizo monitor. Fifty-two subjects discriminated the colour pairs through the blurred (n=26) and cloudy (n=26) low vision glasses from 2 distances, 35 and 70 cm. The response time of discrimination (answer “see the difference” or “not see the difference”) was recorded. The thresholds of colour discrimination of coloured paired (the minimum difference that subjects still perceive) were determined and the CIE 1976 colour difference (dEab*) of the pairs were calculated.
Results: Both LED channels and distances significantly affected the response time for 2 types of glasses. The fastest response time for both types of glasses were found under channels 420, 555 and 615 for short, medium and long wavelengths respectively. The response times under channels 410 and 435 were comparable to channel 420. The minimum dE* of the “see the difference” pairs in the group (coloured pairs in the group were counted if the majority of more than 13 subjects agreed). Through cloudy glasses, at 35 and 70 cm, for all coloured pairs, the average of minimum dE* were found in 475 nm, 525 nm (595 nm was also comparable) and 700 nm for short, medium and long wavelengths. Through blurry glasses, at 35 and 70 cm, for all coloured pairs, the average of minimum dE* were found in 435 nm, 525 nm (595 nm was also comparable) and 660 nm for short, medium and long wavelengths.