Eye movement affects glaucomatous vision

Fort Lauderdale, FL-Researchers in the United Kingdom have shown that face recognition is an issue worthy of study in patients with glaucoma. Preliminary work has suggested that certain eye movement patterns are associated with better face recognition performance in patients with central glaucomatous visual field loss.

“A lot of research in glaucoma tends to focus on clinical measures such as visual fields for detecting and monitoring the disease within a clinical environment; however, it is also important to consider how these largely numerical values translate to the person’s functioning in day-to-day activities,” said Fiona C. Glen, MA, a PhD researcher in the Department of Optometry and Visual Science, City University London, United Kingdom.

“This is going to be information that is most important to the patients. They will want to know what changes to expect in their life, when to expect them, and whether they will still be able to carry out the activities that are most important to them,” Glen said.

Impairment in face recognition ability could be significant as well as extremely distressing for a patient. Glen and colleagues at City University London, Moorfields Eye Hospital, and University College London examined whether patients with glaucoma had difficulty recognizing faces and recently published a paper in Investigative Ophthalmology & Visual Science¹ demonstrating that patients with glaucoma and advanced visual field loss and poor contrast sensitivity were more likely to experience problems with face recognition than people of a similar age with healthy vision.

This research also showed that the type of visual field defect appeared to be important. Patients who had defects closer to fixation, in the central 10º, performed worse at face recognition. However, the researchers noticed that some of the patients were still good at the task despite advanced defects.

“We speculated that some of these patients might be doing something differently that allowed them to perform better at the task, and based on other work we had been carrying out we thought there might be reason to believe that their eye movements were different,” Glen said.

Work presented this spring at the annual meeting of the Association for Research in Vision and Ophthalmology represented the first stage in exploring that theory. In that study, Glen and colleagues recorded the eye movements of 26 patients with glaucoma and 38 age-similar controls. The movements were recorded with an Eyelink 1000 while the subjects performed the Cambridge Face Memory Test (CFMT).

The participants had visual acuity better than 6/9, underwent various visual function tests, and were in good cognitive health. The patients with glaucoma had a median 24-2 mean deviation (MD) of –7.7 dB and significant central 10º visual field defects as defined by 10-2 MD <1% normative value, all in the better eye.

“We found that some of the patients who had advanced loss in the central 10º seemed to show some sort of different eye movement behavior, and some of these patients were also performing very well at the task. However, we did not see as much of an association between eye movement and performance in the people who had normal vision,” Glen said. “It is speculative at this stage, but we believe this could indicate that some patients may use eye movements to help them adapt to their vision loss in activities like face recognition.”

In the patient group, the researchers found a significant partial correlation (controlling for age) between the percent of correctly identified faces in the CFMT and the number of saccades made per second when they first viewed a single face (r = 0.68, p <0.001). No significant association was found between face recognition performance and the number or size of saccades in the controls (r = 0.16, p = 0.34 and r = 0.24, p = 0.16, respectively).

An interesting question for future research is whether some patients are consciously coming up with strategies such as changes in eye movement to help them manage tasks such as face recognition despite their vision defects, or whether it is an unconscious adaptation, Glen said. She added that the research group also is studying eye movement in other tasks and that some of this work is already published.^2,3

Glen did not report any relevant commercial relationships.

References

1. Glen FC, Crabb DP, Smith ND, Burton R, Garway-Heath DF. Do patients with glaucoma have difficulty recognizing faces? Invest Ophthalmol Vis Sci. 2012;53:3629-3637.

2. Crabb DP, Smith ND, Rauscher FG, et al. Exploring eye movements in patients with glaucoma when viewing a driving scene. PLoS One. 2010;5:e9710.

3. Smith ND, Crabb DP, Glen FC, Burton R, Garway-Heath DF. Eye movements in patients with glaucoma when viewing images of everyday scenes. Seeing and Perceiving. 2012;1-22. DOI: 10.1163/187847612X634454.

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