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Saturday stream 1 Session 11.35 - 12.50 Length 25 minutes
P. E. M. Vente , J. E. Bos , W. Bles and G. de_Wit
(1) Rosmolen 100 / 2406 JW Alphen a/d Rijn / The Netherlands. PEM.Vente@kno.nl
Abstract
Purpose: To investigate whether prismglasses according to the guideline of G.P. Utermohlen are useful against car motion sickness Introduction: In the 1940s Utermohlen, prescribed prism spectacles for patients with Meniere's Disease [6]. Later, these glasses were also prescribed for children with dyslexia to improve their mechanical reading skills[1]. It has been well documented that dyslexia may include impairment of the voluntary saccade control, visual attention , abnormalities of vergence and vestibular disorders, [2, 3, 4,], which is why it was thought reasonable to prescribe prism glasses for these patients as well. A side-effect of these prism glasses was the alleviation of car sickness. A placebo effect is unlikely as alleviation of car sickness was not the original intention of the prescription. We herewith present a retrospective study evaluating the effect on motion sickness of wearing prism spectacles. METHODS: Patients were selected by psychologists [5]. We furthermore only used the data of patients who reported at least one emesis ever due to (car) motion. This resulted in 201 patients to be included in this study. Ages ranged from 6 to 15, (average10 years), 115 males and 86 females. The ability to converge revealed by the Maddox rod method showed a clear insufficiency in 137 patients, and an excess in 41. Prism spectacles were prescribed using the Utermohlen method, which consists of two phases:1) careful refraction correction, and 2) prescribing the correct prisms according to the Extended Utermohlen Test (E.U.T.) [6,7,8,9]. This combination seems to be vital for combating the vertigo [8].Follow-up: After six months (1 year on average) patients were reassessed in the same way as before, except that their motion sickness experiences were now rated. Symptoms were rated in three categories:1) no problems, no vomiting, no feelings of nausea; 2) no vomiting, but with some feeling of nausea; 3) no improvements noticed. RESULTS The effect can be quantified as follows: 90% did not vomit at all during the follow-up period. The greatest subjective improvement was achieved in patients with a convergence insufficiency of at least 4 diopters. The ability to converge showed a clear insufficiency in 137 patients, and an excess in 41. In the E.U.T. all patients with dyslexia showed the same deviant walking pattern as do patients with Meniere's disease and this is also susceptible to correction with prisms in the same way. Also the reading skills showed improvement. It was also striking in several cases that motion sickness symptoms returned as soon as the spectacles were not worn (9). DISCUSSION The effect can be quantified to those patients who were obvious vomiters, that is those who vomited at least twice due to motion (186). Of these, 172 (i.e. over 90%) did not vomit at all during the follow-up period. The average age of the present group is just about the optimum of incidence versus age [10], Despite the relatively short follow-up period, we consider this a remarkably high number. For this study we selected only vomiters and not complaints of nausea (malaise) without vomiting . The prism glasses of Utermohlen are mostly prescribed for Meniere's Disease, which is characterised by attacks of vertigo, tinnitus and hearing impairment. The asymmetrical nature of the vestibular weakness is thought to result in asymmetrical stimulation of the oculomotor system, which, in turn induces orientation anomalies. The prism glasses are thought to decrease the discrepancy between visual and vestibular cues, and to reduce the negative effects of vertigo. It is reasonable to assume a vestibular deficit in these patients as well. In addition, it was found that a marked number of these patients showed a convergence insufficiency. This may also interfere with the discrepancy between visual and vestibular cues as discussed above. CONCLUSION In conclusion we state that:1) prism glasses can help in reducing motion sickness symptoms, 2) the present data supports the hypothesis that prism glasses decrease the discrepancy between visual and vestibular orientation cues. 3) we confirm that a marked number of these patients showed a convergence insufficiency, and could be considered as a early precursor for mechanical reading impairment.
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