A view on glaucoma--are we seeing it clearly?

Abstract

Successful clinical management of glaucoma should not simply be about control of intraocular pressure, but must equate to correct decisions about intensifying treatment when patients are at risk of developing 'visual disability'. Yet little is known about what visual field defects, at different stages of glaucoma, specifically affect patients' abilities to perform everyday visual tasks. One way to do this is to measure patient performance in tasks in a lab setting. Another way is to ask patients themselves. The latter can be revealing and demystify views about how patients perceive the world. This short commentary highlights some of the current research in this area.

Figure 1

Humphrey visual field grayscale representations for seven different eyes. The location and spatial extent of the visual field defect is different for each eye but the mean deviation value is—MD =−5 dB for each case. Therefore, information is 'lost' when we only consider the visual field indices.

Figure 2

Six images were shown to 50 patients with bilateral visual field defects. For all six, the same outdoor scene image was used but each was manipulated to provide views of the image obscured and degraded in a range of distinct ways. None of the 50 participants in this study chose the image altered to have ‘a tunnel with black edges' effect or the image with ‘black patches'. Thirteen participants (26%) were completely unaware of their VF defect affecting their visual function, choosing the original unedited image. Twenty-seven (54%) and eight (16%) participants chose the images with ‘blurred patches' and ‘missing patches', respectively. The ‘missing patches' is a very subtle but potentially realistic effect (see the red car) because we used a photograph filling tool to replace the missing parts with the background. Only two participants chose the image with a ‘tunnel with blurred edges' (4%).

Figure 3

A word cloud showing the occurrence of descriptors of glaucomatous vision loss calculated as the number of participants who used the term (a). The size of a word in the visualisation is proportional to the frequency of its use. Similarly, a word cloud of named everyday activities where visual field loss was noticed by an individual is shown in b.

Figure 4

Screenshots of the Glaucoma in Perspective App designed for patients to demonstrate the subtle effect of visual field loss. The user can use the touch screen to draw visual field defects on both eyes. Overlapping defects manifest in the image changing. In this example, a very subtle change occurs in the kitchen scene (right), with kettle and coffee mugs disappearing from the work surface (left), an electric socket disappearing, and an open kitchen cabinet door starting to appear blurred.