Abstract
Purpose:
Lid-wiper epitheliopathy (LWE) is defined as an epitheliopathy of the marginal conjunctiva of eyelids that wipes the ocular surface during blinking, and it is thought to be related to the increased friction that occurs during the blink process. It is also reportedly associated with dry eye. The purpose of this present study was to investigate the relationship between LWE, tear abnormalities, and blink in dry-eye patients.
Methods:
This study involved 45 eyes of 45 female dry-eye patients (mean age: 57.6 years). In all eyes, tear meniscus radius (TMR, mm), spread grade (SG) of the tear-film lipid layer (i.e., SG 1-5: 1 being the best), fluorescein breakup time (FBUT, seconds), LWE grade (LWEG: 3 points maximum) of the upper eyelid, and the Schirmer 1 test (ST1, mm) were evaluated. Blink rate (BR, per minute), palpebral aperture height (PAH, mm), ascending/descending distance (AD/DD, mm) of the upper eyelid, ascending/descending time (AT/DT, msec) of the upper eyelid, and maximum ascending/descending velocity (MAV/MDV, mm/sec) of the upper eyelid were measured by use of a high-speed blink analyzer. Finally, the factors that determine LWEG were investigated by multiple regression analysis in which the parameters were chosen using the stepwise procedure.
Results:
Significant correlations were found between LWEG and SG [R=0.75 (p<.0001)] and FBUT [R=-0.79 (p<.0001)]. LWEG was found to be described as: 0.382 + (0.271 x SG) - (0.437 x FBUT) + (0.005 x MDV) (R2=0.78, p<0.0001).
Conclusions:
Considering that LWEG was described by SG, FBUT, and MDV (which are thought to be related to aqueous tear volume, tear viscosity that affects tear film thinning, and eyelid velocity during blinking, respectively), the present results suggest that LWE of the upper eyelid must be caused by the shear friction, which is described by the following equation:η(viscosity of tear) x U (velocity of eyelid) / h (tear film thickness), acting between lid-wiper region of the upper eyelid and eyeball surface.