Gupta, Wantland and Klien (1996) propose that many of the peripheral equipments used in VR are possible fomites. A fomite is a safe object that is capable to harbour pathogenic organisms and as such, may work as an agent for the transmission of infectivity.
They then propose that airborne pathogens and skin flora flourish in atmospheres as similar to those of HMDs and hand controller devices. An added thought at this point is that HMDs are frequently of enclosed design and produce a substantial heat in powering the displays. This can regularly lead to some sweating for the user particularly if the immersive task needs a definite amount of physical activity.
Both Gupta et al. (1996) and Viirre (1993) propose that there may also be a chance of injury while the user is using a fully immersive HMD. As Viirre proposes, when a user is using an HMD, they are operationally blind in actual terms.
This can cause problems due to conflict with real world objects or probably the VR system cabling and even if the user has some external vision, the forceful immersive scene may divert attention from the real world. Additional, many HMDs also offer sound cues for the user that effectively reduce aural stimulation from the real world.
Physiological problems are probably the most well documented and at present, well researched sickness problem recently credited to VR systems. In fact some accounted physiological side-effects such as simulator sickness have been studied for some time. Of the probable physiological side-effects, visual symptoms and motion sickness type symptoms emerge to cause the most concern. As a result, majority of the studies into physiological results has been focussed in these areas.
The visual presentation of the virtual atmosphere is very significant. The processing and organisation of visual input engages the use of a larger portion of the brain than for any other sense. North (1993) approximated that for a complicated task such as driving, 90 per cent of the received information is visual. It is therefore not astonishing that producers go to great lengths to offer a compelling visual atmosphere.
As proposed however, stereoscopic semi-immersive systems may have added side-effects. One of the prime causes for the origin of side-effects is proposed to be the dissociation of accommodation and union in the visual system.
Indication of Near Market Development
In 1993, Mon-Williams, Wann and Rushton accounted physiological symptoms in many subjects pursued by immersion in an HMD. Of the 20 subjects who contributed in their experiment, 12 complained of symptoms such as headache, eyestrain and nausea and 4 displayed a transient decrease in binocular visual acuity.
The subjects also displayed symptoms of binocular stress that included modifications in heterophoria and an increment in near point of junction. Mon-Williams and Pascal (1995) proposed that these symptoms of visual/binocular stress were connected, not only to poor image quality and close working distance of the screens, but more primarily with the inconsistency between space and convergence requirement when using a stereoscopic HMD.
This problem will take place in any stereoscopic system where the main image is shaped on a flat screen and stereo images are presented by demonstrating slightly dissimilar images to each eye.
In the natural atmosphere, focus and union are essentially connected. If one accommodates (focuses) on a near object, the eyes will automatically unite. Likewise, if focus is transformed to a distant object, the eyes will mechanically deviate slightly (see Figure 1).
Using stereoscopic display devices such as shutter glasses or HMDs, this will not happen. In this situation, the focal demand is always invariable but the convergence demand modifies as the user regards objects at different geometric depths in the virtual world. This accommodation/ convergence is not a natural occurrence and has been said to result in visual stress.
Probable Health Benefits
Mutually Howarth (1994) and Wilson (1996) point out that in addition to looking for problems; it is significant to make out that VR methods may also attest helpful in various applications. Recently there is much investigation work being carried out in the VR field that will be of benefit to users.
In terms of physical issues, more usual interface methods may reduce static posture problems, the use of LCD displays may minimise vision problems associated with CRT displays and physical loads associated with keying (Wilson, 1996).
VR also presents a much improved method for health and safety training, even though as Howarth (1994) proposes, this function is largely concealed. VR methods can be used in ergonomic assessment of workspace plan, for fast prototyping of control interfaces, for the simulation of probably dangerous surroundings such as nuclear plant maintenance and in education and training of users in parts such as the maintenance of complicated machinery.
As Howarth says, the fact that the use of VR has helped an operator avoid an accident or react correctly in the event of a crisis is largely unseen.
VR also has numerous applications that can be directly linked to healthcare. In a white paper on the usage of Virtual Surroundings for Health Care, Moline (1995) shows numerous parts where patient care can be assisted by VR methods. These include:
· The use of VR for remote telesurgery.
· VR methods used in local surgery such as endoscopy, where the surgeon manipulates instruments by viewing a TV monitor.
· VEs used as surgical simulators or trainers.
· VEs used as therapy devices to reduce anxiety or fear. One example is dentists using 3D eyeglasses to divert a patients attentiveness during dental operations
· VEs are also being used to reduce phobias such as agoraphobia and vertigo.
North, North and Coble (1996) present an indication of existing work in the use of VR methods to decrease phobias in their book VR Therapy.
Investigation into the side effects of VR use is a complicated and difficult business and it is clear that concerns do remain about the outcomes of using such systems. Educational investigation does show that some indications happen whilst using VR tools and that these outcomes (such as nausea) can be quite incapacitating in the interim. Whether or not there is a lasting outcome is difficult to find out, partly because of the fact that VR methods are comparatively new and are constantly evolving.
Bolas, M.T. (1994). Human elements in the design of an immersive system. IEEE Computer Graphics and Applications, 14, pp 55-59.
Cobb, S.V.G., Nichols, S.C. and Wilson, J.R. (1995). Health and Safety Implications of Virtual Reality: In Search of an Experimental Methodology. Proceedings of FIVE ‘95 Conference. London, Dec. 1995.
Costello, P.J. and Howarth, P.A. (1996a). Visual issues in virtual atmospheres – Part 1. Optometry Today, March 11 1996 pgs 34-36.
Costello, P.J. and Howarth, P.A. (1996b). Visual issues in virtual atmospheres – Part 2. Optometry Today, April 8 1996 pgs 38-40.
Costello, P.J. and Howarth, P.A. (1996c). The visual results of immersion in four virtual atmospheres. VISERG Internal Report 9604.
Dain, S.J., A.K. McCarthy, and T. Chan-Ling. (1988). Symptoms in VDU Operators. American Journal of Optometry and Physiological Optics, 65(3): 162-167.
Daum, K.M., G. Good, and L. Tijerina. (1988). Symptoms in Video Display Terminal Fatigue in Visual Display Terminal (VDT) Work. Acta Ophthalmologica, Supplement 185:175-176.
Delaney, B. (1996). Drivers in Virtual Rigs. Cyberedge Journal Vol. 6, No. 6, Nov/Dec, pp 1, 4.
Grandjean, E. (1987). Ergonomics in computerised offices. London, Taylor and Francis. Operators and the Presence of Small Refractive Errors. Journal of the American Optometric Association, 59(9): 691-697.
Gupta, S.C., Wantland, C.A. and Klein, S.A. (1996). Cyberpathology: Medical Concerns of VR Applications. Journal of Medicine and Virtual Reality 1996: 1 (2) 8-11.
Havron, M. and Butler, L. (1957). Evaluation of training efficientness of the 2FH2 helicopter flight trainer research tool. Naval Training Device Centre, Port Washington, New York, NAVTRADEVCEN 1915-00-1.
Health and Safety (Display Screen Equipment) Regulations. (1992). No. 2792. London, HMSO.
Howarth, P.A. (1994). Virtual Reality: an occupational health hazard of the future? Presented at RCN Occupational Nurses Forum, Glasgow, Scotland, “Working for Health”, 22 April 1994.
Howarth, P.A. (1996) Empirical Studies of Accommodation, Convergence, and HMD Use. Proceedings of the Hoso-Bunka Foundation Symposium, Tokyo, December 3 1996
Howarth, P.A. (1996). Virtual Reality (VR) Spans the Atlantic. Optometry Today, June 3 1996 pgs 37-38.
Howarth, P.A. (1997). Oculomotor Changes within Virtual Atmospheres. In Press.
Howarth, P.A. and Costello, P.J. (1996). Visual Results of Immersion in Virtual Atmospheres: Interim Results from the UK Health and Safety Executive Study, Presented at the Society for Information Display International Symposium, San Diego,
Howarth, P.A. and Costello, P.J. (1997). The Occurrence of Virtual Simulation Sickness Symptoms when an HMD was used as a Personal Viewing System. Accepted for publication in Displays..
Howarth, P.A. and Istance, H.O. (1985). The association between visual discomfort and the use of visual display units. Behaviour and Information Technology, Vol. 4, No. 2, pp 131-149.
Howarth, P.A. and Istance, H.O. (1986). The validity of subjective reports of visual discomfort. Human Elements 28(3) pgs 347-352.
Kalawsky, R.S. (1996). Exploiting Virtual Reality Techniques in Education and Training: Technological Issues. SIMA Report Series ISSN 1356-5370.
Kellogg, R.S., Castore, C. and Coward, R. (1980). Psychological results of training in a full vision simulator. Annual Scientific Meeting of the Aerospace Medical Association. California, May 12-17, pgs 885-888.
Kennedy, R.S. and Frank, L.H. (1985). A review of motion sickness with special reference to simulator sickness. (AD-A155 975), p.45. Canyon Research Group, Inc., Westlake Village, CA, 15th Apr.
Kennedy, R.S., Berbauum, K.S., Lilienthal, M.G., Dunlap, W.P., Mulligan, B.F. and Funaro, J.F. (1987). Guidelines for alleviation of simulator sickness symptomatology. (NAVTRASYSCEN TR-87007) (AD-A182 554), p.68, March.
Kolasinski, E.M. (1995). Simulator Sickness in Virtual Atmospheres. U.S. Army Research Institute, Technical Report 1027.
Leuder, R. (1986). Work station design. In R. Leuder (ed.), The ergonomics payoff: Designing the electronic office. Toronto, Ont., Canada: Holt, Rinehart and Winston.
Maddox, E.E. (1893). The Clinical Use of Prisms; and the Decentring of Lenses. John Wright and Sons, Bristol, England.
McCauley, M.E. and Sharkey, T.J. (1991). Cybersickness: Perception of Self-Motion in Virtual Atmospheres. Presence, 1, pp 311-317.
Moline, J. (1995). Virtual Atmospheres for Health Care. White Paper for the Advanced Technology Program (ATP). National Institute of Standards and Technology.
Mon-Williams, M. and Pascal, E. (1995). Virtual Reality Displays, Implications for Optometrists. Optometry Today, Jan. 30th, pp 30-33.
Mon-Williams, M., Wann, J.P. and Rushton, S. (1993). Binocular Vision in a Virtual World: Visual Deficits Following the Wearing of a Head-Mounted Display. Ophthalmic and Physiological Optics. 13th Oct, pp 387-391.
National Research Council. (1983). Visual Display, Work and Vision. National Academy Press.
North, M., North, S. and Coble, J. (1996). Virtual Reality Therapy. IPI Press, Colorado Springs, CO, USA.
North, R. (1993). Work and the Eye. Oxford, Oxford University Press.
Pausch, R., Crea, T. and Conway, M. (1992). A Literature Survey for Virtual Atmospheres: Military Flight Simulator Visual Systems and Simulator Sickness. Presence, Vol. 1, No. 3, pp 344-363.
Peli, E. (1995). Real vision and virtual reality. Optics and Photonics News, July, pp 28-34.
Peli, E. (1996). Health and Safety Issues with Head Mounted Displays (HMD). Proceedings of the Hoso-Bunka Foundation Symposium, Tokyo, December 3, 1996.
Pickwell, D., Jenkins, T. and Yekta, A.A. (1987). The result on fixation disparity and associated heterophoria of reading at an abnormally close distance. Ophthalmic and Physiological Optics, Vol. 7, No. 4, pp 345-347.
Regan, E. and Price, K. (1993a). Some side-effects of Immersion Virtual Reality. APRE Report 93R010.
Regan, E. and Price, K. (1993b). Some side-effects of Immersion Virtual Reality: An Investigation Into the Relationship between Inter-Pupillary Distance and Ocular Related Problems. APRE Report 93R023.
Riva, G. (1996). But, Look at it This Way. Cyberedge Journal Vol. 6, No. 6, Nov/Dec, pp 10-11.
Robinett, W. and Rolland, J.P. (1992). A Computational Model for the Stereoscopic Optics of a Head-Mounted Display. Presence 1, pp45-61.
Schor, C.M. (1986). The Glenn A. Fry Award Lecture: Adaptive Regulation of Accommodative Vergence and Vergence Accommodation. American Journal of Optometry and Physio. Optics, 63, pp 587-609.
Sethi, B. (1986). Vergence Adaptation: A Review. Documenta Ophthalmologica, 63, pp 247-263.
Sheehy, J.B. and Wilkinson, M. (1989). Depth Perception after Prolonged Usage of Night Vision Goggles. Aviation, Space and Environ. Med., June, pp573-579.
Shen, C.S., S.B. Chiu, A.H. Wang, and L.S. Ko. (1988). Accommodation and Visual
Shotton, M.A. (1989). Computer Addiction? A Study of Computer Dependency. Taylor and Francis.
So, R.H.Y. (1994). An investigation of the results of lags on motion sickness with a Head-Coupled Visual Display. In: Proceedings of the UK Informal Group Meeting on Human Response to Vibration. Alverstaoke, Gosport, Hants. 19-21 Sept.
Viirre, E. (1994). A Survey of Medical Issues and Virtual Reality Technology. Virtual Reality World, August, pp 16-24.
Wilson, J.R. (1996). Results of participating in virtual atmospheres: A review of current knowledge. Safety Science, Vol. 23, No.1, pp 39-51.
Wilson, J.R., Nichols, S.C. and Ramsey, A. (1995). Virtual Reality Health and Safety: Facts, Speculation and Myths. VR News, Vol. 4, Issue. 9, pp 20-24.
Youngblut, C., Johnson, R.E., Nash, S.H., Wienclaw, R.A. and Will, C.A. (1996). Review of Virtual Atmosphere Interface Technology, Institute for Defence Analyses (IDA), Paper P-3186.