Low luminance reduces face recognition, especially among those with central vision loss
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Key takeaways:
- Facial identity discrimination accuracy decreased by 20.4% under low luminance for those with central vision loss.
- Worse visual acuity and contrast sensitivity were associated with reduced face recognition.
Poor visual acuity and contrast sensitivity may predict worse face recognition under low luminance conditions, particularly in adults with central vision loss, according to research published in Ophthalmic and Physiological Optics.
“Face recognition is a vital aspect of communication and social connection,” Dinesh Venugopal, and colleagues at the School of Optometry and Vision Science at Queensland University of Technology, wrote. “People with vision impairment report difficulties with both discrimination of familiar faces and recognition of facial expressions under a range of conditions, with potential to cause anxiety, embarrassment, avoidance of social situations and social isolation.”
In a study of 17 adults with central vision loss (CVL), 17 with peripheral vision loss (PVL) and 20 controls, researchers assessed facial identity discrimination (FID) and facial expression recognition (FER) under photopic and low luminance conditions.
To assess FID, participants had to identify the odd-face-out from 12 sets of three faces with neutral expressions. To assess FER, participants were asked to name the expression on 12 faces. The researchers assessed photopic and low luminance visual acuity and contrast sensitivity for all groups, using the Humphrey Field Analyzer for the PVL group.
According to results, FID accuracy decreased by 20.4% under low luminance compared with photopic luminance in the CVL group, while FID accuracy decreased only by 7.8% under low luminance in the PVL group. The control group exhibited the same FID accuracy regardless of luminance conditions.
For the CVL group, FER accuracy decreased by 24.7% under low luminance compared with photopic luminance, but both the PVL and control groups exhibited the same FER accuracy regardless of luminance conditions.
The CVL group exhibited worse FID performance than FER under both luminance conditions, while the PVL group exhibited worse FID performance than FER in low luminance but not photopic conditions. The control group exhibited no significant differences regardless of luminance.
Worse visual acuity and contrast sensitivity were associated with significantly reduced face recognition, accounting for 75% of the variance in low luminance FID. Photopic visual acuity proved a strong predictor of face recognition under low luminance conditions, explaining 61% of the variance in low luminance FER.
“The findings indicate that for practical purposes, clinical measures of VA are a good predictor of face recognition under both low luminance and photopic conditions,” Venugopal and colleagues wrote. “Overall, the current study provides a more comprehensive understanding of face recognition under low luminance in adults with CVL and PVL that will be useful for clinicians managing the challenges experienced by patients with low vision.”
Perspective
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Adults with vision impairment frequently report difficulty with facial recognition. This study looked at how adults with both central and peripheral vision impairment performed in facial recognition tasks in low light conditions.
People with central vision loss, compared with peripheral loss and controls, showed the greatest difficulty with facial recognition in these conditions. As one would expect, these results were associated with worse visual acuity and contrast sensitivity. Most optometrists are unlikely to perform low luminance facial recognition testing during a routine clinical exam; however, the study did show that photopic VA is a good predictor of this type of concern. Although this was a relatively small study, it provides valuable clinical information for those addressing these types of concerns in low vision or in primary care. Clinicians can help patients learn to modify the environment to improve this area of visual function.
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