Abstract
Purpose :
Mesopic contrast sensitivity (CS) testing in clinical investigations of intraocular lenses (IOL) is guided by ISO/ANSI standards. The standards require a pilot study in young adults with healthy eyes to determine the illuminance of the glare source. The appropriate illuminance level will be achieved when a decrease of about 0.1 log units at 6 cycles per degree (cpd) is achieved. We conducted a pilot study to determine the appropriate glare level for CS testing with the M&S Technologies, Clinical Trial Suite (CTS) system.
Methods :
One eye of young adults (18 to 40 years) with best-corrected distance vision (BCDVA) of at least 20/20 and no known ocular abnormalities was enrolled. Mesopic CS at 6 cpd was measured with CTS in 40 subjects without glare and with five different glare levels: 44 lux, 68 lux, 89 lux, 150 lux and 188 lux at corneal plane, before 1.5 ND filter at 2.5 meters. The mean difference and two-sided 95% CI of the difference between CS without and with glare was calculated.
Results :
As per the ANSI/ISO standards, eyes with improved CS under glare condition were excluded from the analysis. Following ANSI/ISO criteria, mean decrease in CS with glare at 6 cpd was 0.16 log units for 44 lux (95% CI [0.11, 021] , n=23), 0.18 log units for 68 lux (95% CI [0.14, 0.23], n=31), 0.20 log units for 89 lux (95% CI [0.14, 0.27] , n=31), 0.25 log units for 150 lux (95% CI [0.18, 0.31] , n=30), and 0.29 log units (95% CI [0.23, 0.35], n=34) for 188 lux, all above the 0.1 log unit criterion.
Conclusions :
Following ANSI/ISO criteria, all glare levels tested on CTS exceeded the required 0.1 log units drop at 6 cpd. The current CTS standard glare source (~150-180 lux) provides between 2.5- and 3-times larger drop in CS than required. These results suggest that to meet the ANSI/ISO criteria for mesopic CS testing a lower glare level should be used.
This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.