The Effect of Weighted Contact Lens on Physiological Nystagmus in Young Healthy Subjects

Background and Aim: Contact lenses correct the visual functioning of patients with low vision due to congenital nystagmus. This research presents a new method to reduce nystagmus using contact lenses in healthy subjects. Methods: Thirty-three normal people (13 women, 20 men) aged 18 to 25 with an average age of 23.3 years participated in this study. In the studied subjects, nystagmus was evoked by an optokinetic stimulus. Then, it was measured and recorded. Next, the Conventional Contact Lens (CCL) and a special lens that was designed and made heavier than the conventional lenses were placed in the eyes of the participants. Once again, nystagmus was recorded with the optokinetic stimulus while the contact lens was placed in the participant’s eyes. Results: No significant difference was observed for the Slow Phase Velocity (SPV) and gain of nystagmus with and without CCL (p>0.05), but this parameter had a significant difference with and without Weighted Contact Lenses (WCL) (p<0.05). Also, the comparison between the two lenses demonstrated a significant difference (p<0.05), which indicates the positive effect of the WCL in reducing the SPV and gain of nystagmus. Conclusion: Using weighted contact lenses can significantly reduce the SPV and gain of optokinetic nystagmus in healthy subjects. Investigating the effect of this lens in inhibiting pathological nystagmus is recommended in future research. Keywords: Nystagmus; optokinetic nystagmus; weighted contact lens