Abstract
Purpose :
To investigate the changes in symptoms and corneal thresholds to cooling stimuli in a group of symptomatic contact lens (CL) wearers when habitual CL wear is first ceased (washout phase) and then restarted (re-challenge phase) for 3-month periods, in an attempt to understand the neural mechanisms underlying CL discomfort.
Methods :
Twenty-four symptomatic soft CL wearers (based on Contact Lens Dry Eye Questionnaire-8 (CLDEQ-8) scores and comfortable wearing time) completed the study. Corneal detection thresholds to cooling stimuli (approximately 22°C) were estimated by a modified Belmonte esthesiometer at study entry while still using habitual CLs (BL) and repeated at each month over the 3-month of washout (M1, M2, M3) and 3-month re-challenge phase (M4, M5, M6). The CLDEQ-8 was administered at BL, M4, M5 and M6. Repeated measures ANOVA and post-hoc tests with Bonferroni adjustment were used for data analysis.
Results :
There was a significant difference in detection threshold between study visits (p<0.001), with the threshold increasing gradually (become less sensitive) during no-CL lens wearing washout and then decreasing during the re-challenge phase (Figure 1). The cooling threshold at BL was significantly different than M2, M3, M4 and M6 (all p≤ 0.035), but not M1 (p=0.082) and M5 (p=0.188). The CLDEQ-8 was significantly different between visits (p< 0.001), with CLDEQ-8 scores for M4, M5 and M6 all significantly lower compared to baseline (all p< 0.001) but similar to score during the re-challenge phase (all p≥ 0.941) as shown in Figure 2.
Conclusions :
The study demonstrated that corneal sensitivity to cooling stimuli decreased while symptoms improved following a no-CL washout in a group of symptomatic CL wearers. Sensitivity tended to increase again after restarting CL wear. These results suggest that sensory function contributes to CL discomfort and point to the complex role that corneal sensory processing plays in the group of symptomatic CL wearers.
This is a 2021 ARVO Annual Meeting abstract.