Abstract
Purpose: :
End-of-day (EOD) occurs at different times for different people and possibly with different CLs, making the interpretation of this comfort rating more complicated. A general EOD time point for ratings excludes cases where CLs are removed earlier due to discomfort. A new variable to quantify comfort was developed to incorporate wearing time into the interpretation of EOD comfort by summing the comfort scores for each hour (hr) of lens wear, termed "cumulative comfort".
Methods: :
104 participants wore 3 different types of lenses (Dailies Total1 (DT1), Clariti 1-Day (C1D) and 1-Day Acuvue TruEye (ATE)) each for 3 days. On day 2, comfort ratings were recorded after 4, 8, and 12 hrs of wear and at EOD (prior to removal) using a 0-100 visual analogue scale (VAS). Times of insertion and removal were also recorded.Cumulative comfort was estimated using the available 4, 8, and 12 hr ratings until the removal time was reached. The EOD rating was used for remaining hrs. As an example, if someone was only able to wear their lenses 10 hrs, the cumulative comfort score would be: 4*VAS@4 hrs + 4*VAS@8 hrs + X*VAS@EOD = cumulative comfort score, where X = 2.
Results: :
Mean ± SD comfort ratings at 4, 8, 12 hrs and EOD were 92±9, 88±12, 84±16 and 79±17 for DT1, 88±12, 83±17, 81±17 and 72±21 for C1D and 89±14, 85±16, 83±17 and 78±21 for ATE. Comfort ratings at EOD were higher for DT1 than C1D (p=0.001) but not different to ATE (p>0.05) and wearing times varied from 7 to 19 hrs, with 85, 82 and 79 participants reaching 12 hrs with DT1, C1D and ATE, respectively. Mean ± SD cumulative comfort was higher for DT1 (1184±258) than both C1D (1094±318, p=0.002) and ATE (1122±297, p=0.047).
Conclusions: :
Cumulative comfort was different for two lenses despite similar EOD comfort ratings. Cumulative comfort is an attempt to take into consideration the impact the number of hrs a lens is worn as EOD comfort ratings alone are not reflective of those who might respond to poor comfort by removing lenses earlier than desired.
Clinical Trial: :
http://www.clinicaltrials.gov NCT01371552
Keywords: contact lens • clinical research methodology