WesternU College of Optometry team recommends standardized luminance for visual acuity systems

A team from the College of Optometry at Western University of Health Sciences conducted research on display screen luminance that could improve the accuracy of visual assessment and standardize various testing measures used medically. 

“If the measured visual acuity is wrong, it may lead to errors in clinical decisions like considerations of cataract surgery, treatment with injections for macular degeneration, or the need for retinal surgery that are based on the level of visual acuity measured,” said College of Optometry Professor and Director of Research Pinakin Davey, PhD, OD, FAAO, who led the study. 

The team includes first-year College of Optometry student Kaydee McCray, MS, second-year College of Optometry student Michelle M. Hammond, and David Evans, PhD, of Guardion Health Sciences (VectorVision Inc). They presented a poster, “Luminance and visual acuity: 20/20 may not always mean 20/20!” at the 2018 Annual Meeting of the Association for Research in Vision and Ophthalmology (ARVO) in Honolulu, Hawaii April 29-May 4, 2018. 

Visual acuity is one of the fundamental tests performed in an eye examination. Visual acuity of 20/20 is assumed to be 100 percent vision. This study examined the variability of luminance levels across computerized visual acuity (CVA) systems in different clinics, the variability of luminance across the display surface, and the impact of this variance on measured visual acuity in ocular healthy individuals.

The results of the study show that measured visual acuity is dramatically influenced by luminance levels or brightness levels of the monitor that the vision chart is displayed on.

Luminance is not accounted for in equipment that measures vision in various clinics, Davey said. Different vision measurements are acquired depending on which room or which clinic is used by a patient because luminance is not standardized, he said. 

The results of this study may affect other fields of medicine. 

“The overarching implications in medicine is that luminance is not standardized in computer monitors and any field of medicine that uses computer screens and displays as a diagnostic aid, such as interpreting radiology images like mammograms, CAT scans and other key diagnostic tests, will need standardization,” Davey said. 

The study recommends that luminance levels in CVA units be standardized with continuous monitoring as they tend to vary and are prone to degradation over time.