Heinzman, Zachary1; Linton, Edward1; Marín-Franch, Iván2; Turpin, Andrew2; Alawa, Karam3;
Wijayagunaratne, Anushi1; Wall, Michael1
1University of Iowa Department of Ophthalmology and Visual Sciences; 2Computational Optometry, Curtin School of Population Health, Curtin University
; 3Department of Ophthalmology, Massachusetts Eye and Ear, Harvard Medical School
Purpose: Visual field testing is used extensively in the diagnosis and surveillance of many ocular diseases. Projection-based perimeters are most commonly used and can cost upwards of $30,000. This high price point restricts access to visual field testing, particularly for individuals in low-income areas, such as underdeveloped countries. The purpose of this study is to assess the validity of visual field results from the Iowa Head-Mounted Display (HMD) Open-Source Perimeter, an open-source virtual reality headset programmed for visual field testing. With hardware costs of approximately $150, this system has the potential to improve perimetry access.
Methods: We tested 20 healthy and 9 glaucoma patients on the HMD and Octopus 900 perimeters using the Open Perimetry Interface platform with size V stimuli, a custom grid spanning the central 26 degrees of the VF, and a ZEST thresholding algorithm. Historical data from the Humphrey Field Analyzer (HFA) was also analyzed. Repeatability was analyzed with the repeatability coefficient (RC), and VF defect detection was determined through side-by-side comparisons.
Results: The pointwise RC was 2.6 dB and 3.4 dB for the HMD and Octopus 900 perimeters in ocular healthy subjects, respectively. Likewise, the RC was 4.2 dB and 3.5 dB in glaucomatous patients. Limits of agreement between the HMD and Octopus 900 perimeters were ±4.6 dB (mean difference 0.4 dB) for healthy patients and ±8.9 dB (mean difference 0.1 dB) for glaucomatous patients. Retrospective analysis showed pointwise RCs on the HFA2 perimeter to be between 3.4-3.7 dB for healthy patients and 3.9-4.7 dB for glaucoma patients. VF defects were similar between the HMD and Octopus 900 for glaucoma subjects.
Conclusions: The Iowa Virtual Reality Headset Open-Source Perimeter accurately reproduces visual field defects, is as repeatable as the Octopus 900 perimeter, and is a more portable and less expensive alternative than traditional perimeters.
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