Researchers have recently identified why it is that adults with age-related macular degeneration (AMD) have trouble recognizing and identifying people’s faces, they believe that it could largely be due to abnormal eye movement patterns and fixations associated with the condition.
The findings come from a study published in the January issue of Optometry and Vision Science.
AMD is a condition in which the retina becomes severely damaged, subsequently impairing a person’s vision in the center of the visual field, which makes everything seem blurry.
People with AMD often have extreme difficulty reading faces as a result and aren’t able to properly focus on people’s internal features, such as the eyes, nose and mouth. AMD becomes more common as people get older. The incidence of AMD among Americans aged 40+ years has dropped over the last 15 years.
The researchers carried out a study which compared the ability of AMD patients and normal healthy controls to recognize the internal features of the Mona Lisa, one of the most famous and well known faces in the world. They were able to examine and analyze the interior of the eyes of patients with AMD using a technique called optical coherence tomography/scanning laser ophthalmoscopy (OCT-SLO).
This sophisticated technique allowed the researchers to make microscopic movies of the interior of eye of the patients with AMD, which they then studied to see the movement patterns and fixations (where they looked at) of the patients as they were looking at the face.
The two groups (AMD patients and healthy controls) were found to have numerous differences in their eye movement patterns and fixations. On average, those in the control group were found to have more fixations on the internal features of the face compared to the AMD patients (87 percent versus 62 percent), while AMD patients were more likely to have fixations on the external features compared to the controls (38 percent versus 13 percent).
The authors found that the AMD patients made more frequent eye movements, known as saccades, compared to those with healthy vision. This could indicate that the problem that AMD patients have with recognizing faces is not only due to their overall vision loss, but also related to an abnormality in eye movement patterns.
These abnormal scanning patterns which cause difficulty in reading faces are also associated with other conditions, such as schizophrenia and autism. The researchers have proposed a few reasons behind why these abnormal patterns in AMD patients occur. They believe it could have a lot to do with the way the brain coordinates eye movement.
Another study mentioned how focusing on specific parts of the face, such as the internal features, could improve face perception among AMD patients. Dr Seiple and co-authors conclude:
“That report gives hope that eye movement control training and training of allocation of attention could improve face perception and eye scanning behavior in individuals with AMD.”
Written by Joseph Nordqvist