Conjunctival vascular adaptation related to ocular comfort in habitual contact lens wearers.

PURPOSE: To investigate the bulbar conjunctival vascular responses in habitual contact lens (HCL) and non-contact lens (NCL) wearers after short-term lens wear and their relationships with ocular comfort. DESIGN: A prospective, comparative before-and-after study. METHODS: Twenty-seven subjects (13 HCL and 14 NCL wearers) were enrolled. Microvasculature and microcirculation on the temporal bulbar conjunctiva were imaged at baseline and 0.5 and 6 hours after wearing contact lenses (1-Day Acuvue TruEye; base curve, 8.5 mm; power, -0.50 diopters) on both eyes. The measurements included vessel diameter (D), axial (VA) and cross-sectional (VS) blood flow velocities, blood flow volume (Q), and vessel density (Dbox) and complexity (D0). A Contact Lens User Experience (CLUE) questionnaire was used to assess ocular comfort. RESULTS: No significant change (P > .05) was observed in D, VA, VS, Q, Dbox, and D0 in the HCL wearers after contact lens wear. By contrast, VA, VS, Q, Dbox, and D0 increased significantly after lens wear (after 0.5 and 6 hours) in NCL wearers, compared to the baseline (P < .05). Moreover, the changes from the baseline to 0.5 hours (VA, VS, and Dbox) and 6 hours (VA, VS, Q, Dbox, and D0) after contact lens wear in NCL wearers were significantly greater than that in HCL wearers (P < .05). The CLUE score 6 hours after lens wear was higher in HCL wearers than in NCL wearers (P < .05). It was also significantly correlated with VA, VS, and D0 after 6-hour lens wear in HCL wearers (P < .05). CONCLUSIONS: This is the first study to reveal the relationship between ocular comfort and conjunctival vascular responses in habitual contact lens wearers.