Abstract
Purpose :
Purpose: To investigate effects of ceasing (washout) for 3 months and restarting contact lens (CL) wear for 3 months on the sensory responses to repetitive cooling stimuli.
Methods :
Methods: Twenty-four symptomatic soft CL wearers were included based on Contact Lens Dry Eye Questionnaire-8 (CLDEQ-8) scores ≥ 14 and comfortable wearing time < 8 hours. Thresholds to cooling stimuli were determined using a modified Belmonte esthesiometer while wearing habitual CLs (BL_M0) and repeated at each month over the 3 months of washout (W_M1, W_M2, W_M3) and the 3 months rechallenge phase (CL_M4, CL_M5, CL_M6). At each visit, subjects received three sets of 20 repetitive 22°C cooling stimuli (2 second trials with 10 seconds between) at threshold, 25% below (subthreshold) and 25% above (suprathreshold). Subjects rated the perceived intensity of each repetitive stimulus using a 5-point scale in 0.5 increments. Changes in threshold and intensity ratings for repetitive stimuli were analyzed using repeated measures ANOVA and post-hoc tests.
Results :
Results: Thresholds at each visit increased gradually (become less sensitive) during the 3 months washout and then tended to decrease during the re-challenge phase; the W_M2, W_M3, CL_M4 and CL_M6 were significantly higher than BL_M0 (all p≤ 0.035). The intensity rating to subthreshold repetitive stimuli decreased during both washout and rechallenge phases (both p<0.001). The intensity rating for threshold stimuli decreased during the washout (p= 0.048), in comparison to the BL, while the intensity rating for suprathreshold stimuli showed no significant differences (p> 0.05). There were no significant differences in intensity ratings within each set of repetitive stimuli at any of the visits (all p> 0.05).
Conclusions :
Conclusion: Corneal sensitivity and responses to subthreshold and threshold repetitive cooling stimuli decreased following a no-CL washout period, suggesting possible attenuated sensitization in symptomatic CL wearers. No significant reduction in the responses within each set of repetitive stimuli indicated an altered adaptative function to the repeated cooling stimuli, which persisted despite a 3 months no-CL washout. These results underscore the complex role of corneal sensory processing in contact lens discomfort.
This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.