Abstract
Purpose:
To investigate diurnal blink patterns in contact lens wearers in various environmental conditions.
Methods:
A wearable continuous blink tracking telemetric device was used to record electromyograms corresponding to activity of the orbicularis oculi muscle. Four contact lens wearers were tracked over a period of six days (6-14 hours per day). The first four days (Visits 1-4) consisted of continuous blink recording while wearing each of the following: 1) spectacles; 2) habitual lenses; 3) soft extended wear lens A; and 4) soft extended wear lens B. On the final two days (Visits 5 and 6), the effect of exposure to the controlled adverse environment (CAESM) wearing lenses A and B at separate visits was investigated. Blink rate, as measured by interblink interval (IBI), was the primary outcome variable.
Results:
Mean diurnal IBI was 3.671 (SD 3.94) seconds during lens wear vs 5.095 (SD 5.573) seconds during spectacle wear (p<0.0001). Under non-stressed conditions, there was no difference (p=0.54) in diurnal IBI wearing lens A (IBI: 3.941, SD 4.005 seconds) versus lens B (IBI: 3.932, SD 4.061 seconds). Mean diurnal IBI for lens B (3.62, SD 1.06) decreased significantly (p=0.028) during CAESM challenge. Mean symptom score during the CAESM was 1.02 on a scale of 0 to 4 (0 being none and 4 being worst discomfort) for lens B vs 0.408 for lens A (p=0.073). For both lenses, IBI and symptoms were significantly correlated during CAESM exposure (Spearman coefficients: lens A, -0.3378, p = 0.0037; lens B: -0.5055, p < 0.0001).
Conclusions:
Mean diurnal IBI during spectacle wear was significantly longer than when wearing contact lenses. Mean diurnal IBI during the CAESM was significantly shorter with lens B compared to lens A. This was associated with higher discomfort scores, and a significant correlation between IBI and symptoms. This continuous blink tracking device provides a sensitive method for high-throughput screening of different lens materials and designs by monitoring diurnal blink patterns, comfort, and compensatory responses during a challenge in adverse environmental conditions.
Keywords: 486 cornea: tears/tear film/dry eye •
477 contact lens •
468 clinical research methodology