Purpose: To investigate the relationship between tear meniscus volumes and ocular discomfort during daily soft contact lens wear in symptomatic and asymptomatic wearers.
Methods: Three groups of subjects (n = 20 each) were enrolled. Group 1: symptomatic lens wearers; group 2: asymptomatic lens wearers; group 3: asymptomatic non-lens wearers. Lenses were worn on both eyes and imaged at 2, 4, 6, 8, and 10 hours by optical coherence tomography (OCT). Afterward, a re-wetting drop was instilled onto a randomly selected eye of each subject and re-imaged immediately and at 5, 10, 20, and 30 minutes. Tear meniscus volumes were calculated based on meniscus areas and eyelid lengths. Ocular comfort was also ranked at each time point.
Results: Upper and lower meniscus volumes in group 1 were the lowest among the three groups at each time point (P < 0.05). For each group, meniscus volumes decreased gradually during the 10-hour study period (P < 0.05). Among the individuals in each group, the comfort ratings were linearly correlated with the tear meniscus volumes during the 10 hours of lens wear (r = 0.21-0.47, all P < 0.05).Tear volume increased after re-wetting, but lasted only 10 - 20 minutes. Ocular comfort in groups 1 and 2 increased after instillation, but lasted only 10 and 20 minutes, respectively. Ocular comfort in group 3 did not improve.
Conclusions: Tear volume decreased gradually during lens wear and contributed to the ocular comfort in both symptomatic and asymptomatic wearers. The efficacy of re-wetting was brief.