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Editors Selection IGR 16-4

Clinical Examination Methods: A virtual reality perimeter

Comment by Chris Johnson on:

116724 Validation of a Wearable Virtual Reality Perimeter for Glaucoma Staging, The NOVA Trial: Novel Virtual Reality Field Assessment, Bradley C; Ahmed IIK; Samuelson TW et al., Translational vision science & technology, 2024; 13: 10

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Automated perimeters that utilize a hemispheric bowl that have projected stimuli presented at different locations are a common form of visual field testing. However, they are quite expensive, require a dedicated testing room, are uncomfortable for some older patients, and require trained personnel to administer the test. As a result, portable devices for visual field testing such as tablets and virtual-reality headsets are now being developed. Alignment problems (head and eye), ambient light interference, glare, test distance consistency and other factors limit the utility of using tablets as an alternative means of performing perimetry. Virtual-reality headsets are able to overcome some of these difficulties.

There are a number of potential advantages associated with virtual-reality headsets: (1) they are portable, so testing can be performed anywhere; (2) head alignment can be maintained; (3) patients prefer testing with a virtual-reality headset; (4) virtual-reality headsets are more comfortable for testing; (5) both eyes can be tested at the same time. However, there are also disadvantages: (1) the range of intensities is smaller than for bowl perimeters; (2) older patients are not familiar with using headsets; (3) quantitative comparisons with automated bowl perimetry are still being performed; (4) there is no standard procedure for performing visual field testing with virtual-reality headsets. This paper represents a comparison of results with a headset in comparison to the Humphrey Field Analyzer in a group of glaucoma patients and glaucoma suspects. This is admirable, but there are some difficulties associated with this investigation. (1) The test algorithm, method of determining reliability and other factors are proprietary, which basically means that one is dealing with a black box, making it difficult to assess its true performance, benefits and limitations. (2) Some of the statements are opinions that do not have evidence-based results to support them. (3) There is no indication as to how the headset was calibrated. (4) Much of the conclusions are descriptive rather than quantitative. A more comprehensive and thorough follow up study would be helpful.

What can be done to improve the clinical utility of virtual-reality headsets? When automated perimetry was first introduced, there were many manufacturers who introduced devices, most of which had different methodologies and test conditions, whereas now there are only a few that have similar procedures. It is likely that the same situation will occur for headsets. To overcome some of the current limitations, it is essential that headsets are developed with the intent of performing quantitative visual function testing. Most of the present devices utilize headsets that were originally designed for video game users that have been adapted for vision testing. This severely limits the capabilities of these instruments.

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