A new portable Fresnel magnifying loupe for nystagmus observation: A clinical education and clinical practice setting study

Background: Dizziness is a common complaint of patients treated by primary care physicians. It is predominantly caused by peripheral vestibular disorders; however, central nervous system disorders should be excluded. Examination of the eye movements and nystagmus can help differentiate between central and peripheral diseases; however, it is often not performed appropriately. In medical education practice, nystagmus observation may facilitate an understanding of vestibular function and nystagmus characteristics. Thus, we proposed a medical education practice to master nystagmus observation using a recently developed portable Fresnel magnifying loupe that could be shielded by one eye. Methods Thirty-three students from the Department of Physical Therapy and the Department of Speech, Language, and Hearing Therapy of the Mejiro University participated in this study. Postrotatory nystagmus was measured and compared using the new loupe and control methods, namely the naked eye and Frenzel goggles; we rated the ease of visibility using a five-point scale. Results The number of cases of nystagmus was significantly higher with the new loupe than with the naked eye ( p  = 0.001). In addition, there were no significant differences in the nystagmus counts between the observations using the new loupe and Frenzel goggles ( p  = 0.087). No significant difference was observed in the visibility of eye movements between the loupe and naked eye ( p  = 1.00). The Frenzel goggles provided better visibility compared to that by the loupe ( p  = 0.034); however, none of the participants reported poor visibility using any of these methods. Conclusions The Fresnel magnifying loupe was superior to the naked eye and equivalent to the Frenzel goggles for nystagmus observation. Moreover, it has several advantages, such as being lightweight, thin, durable, and portable, compared with the Frenzel goggles. The loupe does not require a power source and can be observed under normal room light. It can be used without contact with patients and disinfected with alcohol. Furthermore, it is less expensive than the conventional Frenzel goggles and can be easily used in student practice. Trial registration: This study was approved by the Medical Research Ethics Committee of Mejiro University (approval number: 21medicine-021).