Contrast sensitivity measured by two different test methods in healthy, young adults with normal visual acuity

Area of Science:

• Ophthalmology
• Visual Science
• Optometry

Background:

• Establishing reliable contrast sensitivity (CS) reference values is crucial for assessing visual function.
• Previous studies have yielded varied results due to differences in methodology and population selection.
• Normal visual acuity does not guarantee optimal contrast sensitivity.

Purpose of the Study:

• To determine contrast sensitivity (CS) and index of contrast sensitivity (ICS) reference values in healthy young adults with normal uncorrected visual acuity.
• To evaluate the agreement between two different CS test methods (Optec 6500 and CSV-1000E).
• To assess the utility of the index of contrast sensitivity (ICS) for comparing different CS measurement techniques.

Main Methods:

• A cohort of 180 military recruits aged 18-25 years with 0.00 LogMAR or better visual acuity and normal color vision were recruited.
• Contrast sensitivity was measured using the Optec 6500 (FACT) under photopic and mesopic conditions and the CSV-1000E under photopic conditions.
• The Bland-Altman technique was employed to analyze the agreement between the index of contrast sensitivity (ICS) values derived from the different tests.

Main Results:

• Contrast sensitivity data exhibited a significant ceiling effect, particularly in photopic conditions.
• Median ICS values varied across tests and lighting conditions: Optec 6500 (85 cd/m2) was -0.15, Optec 6500 (3 cd/m2) was -0.00, and CSV-1000E was 0.30.
• There was poor agreement between mesopic and photopic test results (mean difference -0.43), suggesting they are not interchangeable.

Conclusions:

• Reference values for contrast sensitivity (CS) and index of contrast sensitivity (ICS) were established for a young, healthy adult population.
• Photopic tests demonstrated interchangeability, while mesopic testing showed limited agreement with photopic conditions.
• Mesopic contrast sensitivity testing may be more suitable for differentiating candidates in medical selection processes.