Abstract
Purpose:
To evaluate the impact of time of day and length of wear on contact lens (CL) comfort in subjects who are asymptomatic (ASYM) and symptomatic (SYM) for end of day CL discomfort.
Methods:
24 adapted soft CL wearers were enrolled (10 ASYM and 14 SYM). Classification was according to intensity and frequency of late day dryness [Young et al. 2011] and the difference between total and comfortable wearing time (≤ 2hrs for ASYM; ≥ 3hrs for SYM). Biofinity CLs were worn bilaterally for six cycles. Cycles 1 and 2 included 12 hours of spectacle and CL wear, respectively. Cycles 3-6 included 3hrs of lens wear at different times of the day (8am-11am, 11am-2pm, 2pm-5pm and 5pm-8pm, respectively). Cycles were completed in random order on separate days. In all cycles comfort was rated hourly using a 0-100 visual analogue scale.
Results:
The ASYM group had minimal change in comfort with spectacles or CLs over the 12-hour cycle (4±8 and 13±16, respectively, both p>0.05). Comfort in the ASYM group did not reduce significantly over any 3-hour wearing period in cycles 3-6 (2±6, 3±5, 4±5 and 4±6, respectively, all p>0.05). Comfort declined significantly in the SYM group with CLs over the 12-hour cycle (32±21, p<0.01), but not with spectacles (6±15, p>0.05). The change in comfort for the SYM group during cycles 3-6 was 2±9, 8±15, 14±13 and 14±15 and was statistically significant for cycles 4-6 (p<0.05). The decline in comfort with 12hrs of wear was greater than the maximal change over 3hrs (32±21 vs. 14±15, respectively, p<0.05).
Conclusions:
In this study comfort was negatively impacted by both time of day and length of wear in subjects who were SYM for end of day CL discomfort.