Effect of induced glare on pupil size in ocular healthy adults

Abstract

Purpose : Glare testing in clinical setting is complicated due to the lack of clear gold standard. This becomes particularly important when evaluating for cataract surgery where decisions are made on the basis of changes in visual performance with glare. We sought to investigate two calibrated glare inducing systems and evaluate the change in pupil size when the light levels were standardized.

Methods : One hundred eyes of 50 individuals in age range 20 to 35 were included in the study. Subjects underwent an ocular health examination that included vision testing, fundus photography and measurements with Optical Coherence Tomography. The glare units were placed at 8 feet viewing distance from the subject. The glare system 1 (GS1) involves LED light illumination and is constructed with four LED lights at four corners of the monitor. The glare system 2 is a retro illuminated chart with two halogen lamps placed at either side of the box. The background illumination of GS1 and GS 2 system measured at 1 foot was 3 and 25 lux. With the glare levels turned on both units were set at 48 lux. Pupillary measurements were obtained twice using NeurOptics® VIP™-200 with glare system off and glare system turned on.

Results : Figure 1 provides the pupil size with and without induced glare. The baseline pupil measurements when inducing glare GS1 LED system had pupil size of 5.93 which decreased to 4.01 mm with glare. The baseline pupil measurements when inducing glare GS2 halogen system had pupil size of 5.46 which decreased to 3.96 mm with glare. The change in pupil size was significant with both glare systems (Paired samples t-test t=23.77; p<0.001 and t=23.41; p<0.001). The pupil measurements without the glare lights on was different when using the GS1 versus GS2 with pupil 0.47 mm larger when using GS1 (Independent samples t-test t= 7.29; p<0.001). The pupil size was not significantly different when the glare lights were turned on (Independent samples t-test t= 1.12; p=0.26).

Conclusions : Difference in background illumination of glare systems caused a measurable difference in pupil size at baseline. The calibration of glare systems is an important factor in predicting the outcome of visual performance and should be considered when using different glare units. The pupil size is not affected by the glare source; LED versus Halogen.

This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.