Lid Wiper Microvascular Responses as an Indicator of Contact Lens Discomfort

PurposeTo analyze quantitatively the alterations in the microvascular network of the upper tarsal conjunctiva, lid wiper, and bulbar conjunctiva relative to ocular discomfort after contact lens wear.DesignA prospective, crossover clinical study.MethodsFunctional slit-lamp biomicroscopy was used to image the microvascular network of the upper tarsal conjunctiva, lid wiper, and bulbar conjunctiva. The microvascular network was automatically segmented, and fractal analyses were performed to yield the fractal dimension (Dbox) that represented vessel density. Sixteen healthy subjects (9 female and 7 male) with an average age of 35.5 ± 6.7 years (mean ± standard deviation) were recruited. The right eye was imaged at 9 AM and 3 PM at the first visit (day 1) when the subject was not wearing contact lenses. During the second visit (day 2), the right eye was fitted with a contact lens for 6 hours. Microvascular imaging was performed before (at 9 AM) and after lens wear (at 3 PM). Ocular comfort was rated using a 50-point visual analog scale before and after 6 hours of lens wear, and its relationships with microvascular parameters were analyzed.ResultsThere were no significant differences in Dbox among the upper tarsal conjunctiva, lid wiper, and bulbar conjunctiva among the measurements at 9 AM (day 1 and day 2) and 3 PM (day 1) when the subjects were not wearing the lenses (P > .05), whereas after 6 hours of lens wear, the microvascular network densities were increased in all 3 of these locations. Dbox of the lid wiper increased from 1.411 ± 0.116 to 1.548 ± 0.079 after 6 hours of contact lens wear (P < .01). Dbox of the tarsal conjunctiva was 1.731 ± 0.026 at baseline and increased to 1.740 ± 0.030 (P < .05). Dbox of the bulbar conjunctiva increased from 1.587 ± 0.059 to 1.632 ± 0.060 (P < .001). The decrease in ocular discomfort was strongly related to the Dbox change in the lid wiper (r = 0.61, P < .05). There were no correlations between the changes of ocular comfort and the microvascular network densities of either the tarsal or bulbar conjunctivas (P > .05).ConclusionsThis study is the first to show that the microvascular network of the lid wiper can be quantitatively analyzed in contact lens wearers. The microvascular responses of the lid wiper were significantly correlated with contact lens discomfort.