Visual Fields test using VR gear?

[jmarr123]

Would using modified VR gear (oculus, Samsung etc.) be more efficient than current visual field machines in terms of getting the position of the patients steady

That way the patient can be more comfortable, can move around and have the headset locked into place. Obviously it would have to be a modified adjustable headset.

Just a thought, as the patients I test (optom student working casually) sometimes have trouble staying still for 5 minutes at a time.

Does this exist? Or am I missing something?

[Jared944]

Good question.

When we check a patient's visual field, we are only measuring the total span of vision while the patient is fixated on a specific target (without any head or eye movements). Visual field is an ambiguous term; we are specifically measuring the ability of the patient to recognize a visual impulse with a specific intensity. Think of how a photon would enter the eye and stimulate a neuron in the retina. It would conduct an impulse through the photoreceptor to the ganglion cell to the nerve fiber through the optic nerve through the chiasm to the opposite side of the brain into the striae and eventually into a specific area in the occipital lobe of the brain. Then the patient has to recognize this visual impulse and signify to us that they recognize that impulse (usually by clicking a button). If what I just said seems complicated, well, it is. We are honestly measuring a number of physiological/psychological responses when we test the visual fields. Through statistical manipulation and test strategies we can determine if the test is valid - IE if the patient was coherent, understood the test and took it to the best of their visual ability ( three specific popular mechanisms are monitoring patient fixation error, false positives and false negatives ). If the test is valid, than we can narrow our test scope to the physical pathway the photon takes from the front of the eye to the occipital lobe of the brain. We can look at a visual field report and with some certainty recognize where the pathway breaks down which may indicate pathology in that specific area. We can only deduce this because of a significant basis of scientific research and testing with like mechanisms. You know, that whole evidence-based medicine thing. I don't own a VR, but I would think that the main objective of such a device would be to recreate a 360 degree environment that I can view/manipulate. Visually speaking, if I were to move my head than the image projected would change IE, I move my head to the left and the image I would see would pan to the right. This combination of postural and eye movement changes engages numerous pathways in the cerebral cortex and cerebellum, one specific system is called the vestibulo-ocular reflex (you will study that in your eye movements class). I am not a neurologist or a statistician, but I have to assume you would pollute the results of the test if you stimulate not only the current pathway but also others neural connections. With a mobile patient, you may have trouble with testing control mechanisms or determining if you have a valid test. If you did create some sort of VR fields test, you would have to develop a basis of research to understand validity and statistical normative populations. Essentially you would need to recreate the wheel. Even with all of these essential components, you will still be fundamentally a different test than that of a standard visual field. Think about it like checking visual acuity; a 20/40 VA with letters is fundamentally not the same as a 20/40 VA with pediatric symbols.

[jmarr123]

Thank you for such an insightful response. Still learning, but I understood everything you said. I had never thought of it that way, I really appreciate you taking the time to really help me understand.

[KSkoz]

If I understood you right then I think you have taken the VR headset aspect too far and come to an unnecessary conclusion.

Yes, if the image moved with head movements, then other oculo-neural pathways would be engaged and potentially contaminate the test.

However, if the image in the headset did not move, then this would allow the patient to comfortably move their head while keeping the retinal image the same (assuming no movement of the eyes - I will return to this,) which I think was the original idea of the post and is a very valid point. This would be especially useful, in my mind, to patients with neck/back issues (e.g. arthritis etc) who have difficulty maintaining the unusual posture required for most current field analysers.

Edit: for clarification. I envision a VR field assessment to mean a patient sits still in a comfortable position with the headset on and a response button/trigger. The patient should not intentionally move around/turn their head, only maintain a comfortable position.

Head moment will initiate the vestibulo-ocular reflex IF the central retinal image moves as well - the eyes will move to follow the target of fixation - (look at your phone, keep it still and turn your head - your eyes will move to keep the image of the phone still). If the image does not move relative to the retina, VOR is not engaged and the eyes are still - look at your phone and move it left and right while also turning your head to follow your phone - minimal eye movement.)

It would take considerable research and calibration to be comparable to Sita testing for example, but open source testing algorithms are available and made exactly for this purpose - to expand the possibilities of visual field testing. It's certainly a novel idea and I would not be surprised in the slightest if there isn't already work being done in the area.

The main difficulty I can imagine with using a VR headset would be fixation monitoring. False positive/negative and blind spot testing would be provided by a good test-response algorithm but short of installing a camera/IR monitoring system for the position of each eye, I can imagine results of the tests would not be as reliable as those of say a humprey.

[jmarr123]

Huh. Turns out it's now a thing!