An investigation to determine the influence of illumination sources on colour discrimination in normal subjects and smokers

  • Kalpen Mistry

Student thesis: Doctoral ThesisOphthalmic Doctorate


Accurate colour vision testing requires using the correct illumination. With the plethora of 'daylight' lamps available, is there a cost-effective alternative to the discontinued MacBeth Easel lamp? Smoking is a known risk factor for macula degeneration. As the macula is responsible for colour discrimination, any toxin that affects it has the potential to influence colour discrimination.
Aims: To find a costeffective light source for colour vision testing. To investigate the effect of smoking on colour discrimination. To explore how deuteranomalous trichromats compare with normal trichromats.
Methods: Using the Ishihara colour vision test subjects were classified into the groups: 'Normal/Control', 'Smoker/Test', and 'Case Study' (subjects who failed the screening test and did not smoke). They completed the Farnsworth Munsell 100 Hue test under each of the three light sources: Phillips EcoHalo Twist (tungsten halogen - THL), Kosnic KCF07ALU/GU10-865 (compact fluorescent- CFL), and Deal Guardian Ltd. GU103X2WA4B-60 (light-emitting diode - LED) Results: 42 subjects took part in the study: 18 in the Normal/Control group, 18 in the Smoker/Test group, and 6 in the Case Study group. For the Normal/Control group the total error scores (TESs) were significantly lower with the CFL than with the THL (p = 0.017) as it was for the Case Study group (p = 0.009). No significant differences were found between the Normal/Control group and the Smoker/Test group for each light source. Decision tree analysis found pack years to be a significant variable for TES. Discussion: All three light sources were comparable with previous studies. The CFL provided better colour discrimination than the LED despite them both being 6500 K. Deuteranomalous trichromats showed a greatest deviation than normal trichromats using the LED.
Conclusions: The Kosnic KCF07ALU/GU10-865 is a cost-effective alternative for colour vision testing. Smoking appears to have an effect on colour vision, but requires further investigation.
Date of Award9 Mar 2015
Original languageEnglish
Awarding Institution
  • Aston University
SupervisorRobert P Cubbidge (Supervisor)


  • colour vision
  • smoking
  • tungsten halogen lamps
  • compact fluorescent lamps
  • light-emitting diodes

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