Cone-isolation contrast sensitivity - do pupil and stimulus sizes matter?

Area of Science:

• Ophthalmology
• Visual Science
• Optometry

Background:

• Computer-based color perception tests aid in assessing cone-specific pathways.
• These tests are crucial for diagnosing hereditary and acquired color vision deficiencies.
• Understanding factors influencing these tests can improve their clinical utility.

Purpose of the Study:

• To evaluate the impact of pupil diameter and stimulus size on cone contrast sensitivity (CCS).
• To assess CCS using the ColorDx device across different stimulus sizes and chromaticities.
• To determine how variations in pupil size affect color perception measurements.

Main Methods:

• Forty young adults (21-31 years) participated in the study.
• Two stimulus sizes (small: 2.68°, large: 8.58°) and three chromaticities (L, M, S-cones) were used.
• Subjects were tested with natural pupil size (4-5 mm) and a 2.5-mm artificial pupil.

Main Results:

• Pupil size significantly affected CCS for all three cone types (p < .001).
• Stimulus size significantly impacted M-cone (p = .015) and S-cone (p < .001) sensitivity.
• No significant interaction was found between pupil size and stimulus size.

Conclusions:

• Reduced retinal illuminance affected CCS across all conditions.
• Only S-wavelength CCS showed a significant difference between small and large stimuli with a 2.5-mm pupil.
• Further research is needed to explore CCS changes in older individuals with varying pupil sizes.