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Study investigates patient perception of visual field defects
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COPENHAGEN, Denmark — A study carried out at the City University London and Moorfields Eye Hospital investigated patients’ perception of glaucoma-related visual field defects.
“Patients are often misled by images shown in the Web that are meant to depict the visual symptoms of the disease. What they see ubiquitously is black tunnels and black patch effects,” David Crabb, MD, said at the European Glaucoma Society meeting.
David Crabb
The perception of visual field defects is more complex. Compensatory mechanisms are involved, so patients are not aware of visual symptoms until the late stages of the disease.
“When they compare the black tunnel images with the way they see, they might become convinced that they do not have glaucoma and do not need to take medications,” Crabb said. “To raise awareness about symptoms or lack of symptoms, we need to depict visual symptoms better.”
The study was based on interviews in which patients described their visual experience and on the presentation to patients of a series of images in which the same view was modified by a black tunnel, a blurred tunnel, black patches, blurred parts and missing parts.
“Black areas and tunnel vision did not describe the visual experience of the patients in our study. A combination of ‘blur’ and ‘missing’ areas appeared to be more realistic,” Crabb said.
These findings were used to generate images more representative of what patients may or may not see when their visual field defect reaches the point at which they have symptoms.