Saturday 23 March 2013

How does glaucoma look?

A study has found that patients with glaucoma do not perceive their vision loss as a black tunnel effect, which is commonly shown in images and simulations of what patients with the condition are believed to perceive.
Fifty patients with visual acuity better than 20/30 and with a range of glaucomatous visual field defects in both eyes were included in the study. 
All participants were shown six manipulated images of an outdoor scene. Each image was manipulated to provide views of the image obscured and degraded in a range of distinct ways: a tunnel with black edges, a tunnel with blurred edges, black patches, blurred patches and missing patches.
Patients were asked to select the image that most closely represented his or her perception of their visual field loss.
Writing in the journal Ophthalmology, the research team reports that none of the patients chose the images with a distinct black tunnel effect or black patches. Only two patients chose the image with a tunnel effect with blurred edges.
Thirteen participants were completely unaware of their visual field defect affecting their visual function, choosing the original unedited image.
Fifty four percent of patients chose an image depicting blurred patches while 16% chose one with missing patches. 
The researchers said: “The results from this study are important in terms of stimulating the design of appropriate information about the visual symptoms of glaucoma.”

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