Advanced Vision Analyzer: Is virtual reality perimetry the next big thing?
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Amar Agarwal, MS, FRCS, FRCOphth, is a master surgeon, prolific writer and superb educator. He just submitted his 200th column to OSN on ocular surgery complication management. I want to personally thank him for this exceptional achievement.
Richard L. Lindstrom, MD
OSN Chief Medical Editor
An immersive and simulated experience generated by virtual reality technology is rapidly transforming medical health care.
The benefit of VR is its adaptability and numerous applications that can be modified to conform to different medical niches. Currently, health care organizations are adopting VR technology that encompasses diagnosis, robotic surgery, skills training and surgery simulation. So, the question arises: Can automated perimetry on a VR platform take over the standard automated bowl perimetry?
The Advanced Vision Analyzer (AVA, Elisar Vision Technology) is a novel VR automated headset perimeter that allows visual field tests to be performed in patients with suspected visual field involvement. AVA has four basic components: a headset or head-mounted device (HMD; Figure 1), a patient response (PR) button, a tablet and a backend server. The HMD has an adjustable headband, and it also allows adjustment of the interpupillary distance. Trial lenses can be placed for refractive error correction, and the test can be performed without the need to close one eye. Goldmann size III stimulus is presented, and the patient presses the PR button upon visualization of the stimulus, after which the response is recorded and saved. 30-2, 24-2 and 10-2 strategies are integrated into the device, which houses three types of algorithms: full threshold, Elisar standard and Elisar fast. AVA has its own normative database incorporated into the device.
Source: Priya Narang, MS, Amar Agarwal, MS, FRCS, FRCOphth, and Ashvin Agarwal, MD
The eye tracking system tracks eye movements while the visual field test is ongoing, and it offers qualitative assessment and helps to check for fixation loss. False positive and false negative catch trials are incorporated into the device; these trials are stringent and help to validate the reliability of the visual field test.
We are the lead investigators for assessment of the clinical performance of AVA. The device demonstrated satisfactory test-retest variability and accurate blind spot localization with no lens rim artifacts. In a major clinical trial in a group of glaucomatous and normal cases, AVA (Elisar standard algorithm) demonstrated competitive diagnostic accuracy when compared with Humphrey field analyzer (HFA; SITA standard). The clinical trial that compared AVA with HFA depicted agreement of values of mean sensitivity, mean deviation and pattern standard deviation between the devices. The pointwise sensitivity evaluation of all locations in the 24-2 visual field showed strong correlation with similar points on HFA.
Because AVA is a portable device, it has the potential to be an integral part of telemedicine by allowing the performance of visual field tests even in remote areas of the world. The reports (Figure 2) can be shared at the tertiary care level with an ophthalmologist, and opinions can be sought. Hence, with the availability of remote clinical services, tremendous improvement in the level of medical care can be achieved. The patient’s data can be stored on the cloud backend server, and reports can be retrieved when needed. The VR headset is lightweight, and it can be positioned on the patient’s head in reclining, semi-reclining or any other position that is comfortable to the patient. Patients with neck or spinal deformities or with neurological disorders who cannot attend the clinic can perform the visual field test with ease at their home.
AVA has made indelible improvements to the assessment of visual fields and has a far-reaching impact that can improve the lives of people with an appropriate diagnosis, which eventually translates into early and better treatment.
- Reference:
- Narang P, et al. Ophthalmol Sci. 2021;doi:10.1016/j.xops.2021.100035.
- For more information:
- Amar Agarwal, MS, FRCS, FRCOphth, director of Dr. Agarwal’s Eye Hospital and Eye Research Centre, is the author of several books published by SLACK Books, sister company of Healio publisher Ocular Surgery News, including Phaco Nightmares: Conquering Cataract Catastrophes, Bimanual Phaco: Mastering the Phakonit/MICS Technique, Dry Eye: A Practical Guide to Ocular Surface Disorders and Stem Cell Surgery and Presbyopia: A Surgical Textbook. He can be reached at 19 Cathedral Road, Chennai 600 086, India; email: aehl19c@gmail.com; website: www.dragarwal.com.
- Ashvin Agarwal, MD, can be reached at Dr. Agarwal’s Eye Hospital, #222, TT Krishnamachari Road, Alwarpet, Chennai- 600018, India; email: agarwal.ashvin@gmail.com.
- Priya Narang, MS, can be reached at Narang Eye Care & Laser Centre, Ahmedabad, India; email: narangpriya19@gmail.com.
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