THE ROLE OF CONTACT-LENSES IN ELECTRONYST AGMOGRAPHY

During electronystagmography it is necessary to correct defective Visi on for calibration, smooth pursuit, and saccadic eye movements. Theref ore more and more people use contact lenses instead of normal glasses. Given the lack of detailed information about this phenomenon, in the current literature we decided to investigate the influence of soft con tact lenses on electronystagmography. The aim of this study was to fin d out differences in the results of electronystagmography between usin g glasses or contact lenses. Methods: Our investigation involved 20 ve stibular healthy human subjects with myopia. In the first part of the examination they used their contact lenses and in the second part they were wearing normal glasses. After measuring the calibration potentia l we wanted to see if contact lenses would increase the rate of artifa cts in the electronystagmogram. Then we attempted to determine whether contact lenses have an influence on the registration of the optokinet ic nystagmus. Induced saccadic eye movements were recorded and analyse d. Results: Contact lenses had a negative influence neither on the cal ibration potential nor on the rate of artifacts. The latency of the sa ccadic eye movements also showed no differences between both parts of this investigation. Only the velocity of the saccades and the gain val ue during the optokinetic test were reduced when glasses were used. Co nclusions: Contact lenses may stimulate the secretory function of the lacrimal gland and thus decrease friction forces. It is also possible that the reduced image size produced or the reduction-effect of minus by glasses in near sighted persons negatively influences eyeball veloc ity. In summary, our study demonstrates that contact lenses do not hav e a negative influence on electronystagmography. Therefore electronyst agmographic studies of patients with contact lenses are permissible fo r purposes of documenting a medical opinion.