[Clinical study on microcirculation changes of bulbar conjunctiva after contact lens wear].

Objective: To explore the changes of microcirculation of the bulbar conjunctiva after wearing the contact lens and the relationship between contact lens discomfort and bulbar conjunctiva microcirculation. Methods: Prospective cohort study. The postgraduate students from School of Ophthalmology & Optometry and School of Biomedical Engineering of Wenzhou Medical University were included in this prospective cohort study. The subjects wore soft contact lenses, and the right eye was selected as the experimental eye. The ocular surface disease index (OSDI) questionnaire, Schirmer I and tear break-up time tests were completed before and after wearing the contact lens, and the conjunctival blood flow velocity and microvascular network density were also assessed by using functional slit lamp biomicroscopy. The changes of the indicators after wearing the contact lens were observed and the correlation between the subjective feelings of the wearers and the microcirculation parameters of the bulbar conjunctiva and the main factors affecting the subjective feelings of the wearers were analyzed. Results: Twenty-seven subjects were enrolled in the study, including 8 males and 19 females, aged (22.7±1.6) years. The OSDI score was 11.860± 7.783 before wearing the contact lens and 24.017±12.181 after wearing the contact lens. The comparison before and after wearing the contact lens was statistically significant (t=-4.356, P<0.001). The conjunctival blood flow velocity was (0.534±0.132) mm/s before wearing the contact lens and (0.587±0.134) mm/s after wearing the contact lens. The comparison was statistically significant before and after wearing the lens (t=-2.076, P=0.048). OSDI was positively correlated with blood flow velocity at 1 month after wearing the contact lens (correlation coefficient r=0.383, P=0.048). The test results of the independent variables in the generalized estimating equation model showed that time and blood flow velocity were statistically significant (P<0.05). Conclusions: The blood flow velocity of the bulbar conjunctiva was increased after wearing the contact lens, and the contact lens discomfort of the wearers was positively correlated with the blood flow velocity of the bulbar conjunctiva. (Chin J Ophthalmol, 2019, 55: 98-104).