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Glaucoma affects recognition of gender, facial expression
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Patients with glaucoma, even when visual acuity is still good, require a significantly shorter viewing distance to recognize gender and facial expression as compared with healthy subjects, which may be due to higher sensitivity to crowding, according to a study.
When questioned about their difficulties with everyday life, patients with glaucoma often report having difficulties with face recognition, a skill that is critical for social interaction.
A group of researchers at two French universities investigated the effect of viewing distance on face recognition skills in 16 patients with glaucoma and 16 age-matched controls. The age range was 48 to 80 years. Faces were centrally displayed on a screen at six sizes, from 0.75 m to 24 m, simulating different viewing distances.
Patients were asked to recognize gender and facial expressions, namely happy, angry and neutral. Each of the three facial expressions were presented five times with male faces and five times with female faces, for a total of 30 trials.
Glaucoma patients needed a significantly shorter distance and, therefore, a larger size image, to recognize gender and expression than the controls. Gender was recognized at a longer distance than expression, and happy faces were recognized at a longer distance as compared with angry and neutral faces.
A subgroup analysis, where patients with lower visual acuity were excluded, showed that patients with glaucoma and normal acuity still require longer distances than controls. Age also had no significant influence on the results.
“We suggest that the patients requiring larger faces than those of the controls might result from a higher sensitivity to crowding, which alters the appearance of faces and increases the difficulty to perceive the relevant features for recognition of sex and facial expressions,” the authors wrote. Crowding, they explained “describes an inability to recognize an object (or a letter) when other objects (letters) are present nearby.”
Further studies on a large number of patients are needed to corroborate this hypothesis, they concluded. – by Michela Cimberle
Disclosure: The authors reported no relevant financial disclosures.
Perspective
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Carl H. Jacobsen, OD, FAAO
“Glaucoma affects peripheral vision first, but may progress to affect central vision in advanced disease.” This is what I was taught, and this is what I tell patients on a daily basis. Is it true? Not entirely.
OCT teaches us that macular ganglion cells may be damaged early in glaucoma with subsequent loss of paracentral visual field. Behavioral studies find glaucoma patients have relative deficits in motion, shape and object perception – abilities requiring central vision. Schafer and colleagues have found that another central vision-mediated ability, face perception, is also affected by glaucoma.
Successful social interactions are dependent on being able to accurately assess a person’s face. In this study, glaucoma patients needed to be closer to their subject to determine sex and mood. Might this impact our patients? Possibly so, but probably not. Still, it is good to know that the effects of glaucoma reach further than previously thought.
Next time you have a patient with the odd complaint of having difficulty recognizing people, understand that it might be a bona fide complaint caused by glaucoma.
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