Influence of eyelid pigmentation on the diagnosis of meibomian gland dysfunction

To determine whether reliance on eyelid margin vascularization as a diagnostic criterion for meibomian gland dysfunction (MGD) results in underdiagnosis of MGD in individuals with dark skin pigmentation. This cross-sectional study enrolled consecutive cornea clinic patients in Buffalo, New York. Eyelid margin vascularization was graded qualitatively from slit-lamp photos. Skin pigmentation was quantified from digital photos using red/green/blue (RGB) pixel analysis and dichotomized using the RGB median. MGD was defined as abnormal quantity or quality of meibum or increased pressure required to express meibum. Additional testing included infrared meibography, Schirmer's testing, and a dry eye questionnaire. Sensitivity of MGD diagnosis by visualization of vascularization, compared to diagnosis by expression of meibum, was estimated with and without stratification by skin pigmentation. Among 47 participants, 15-79 years old, meibomian gland truncation/dropout, abnormal tear production, and dry eye symptoms affected individuals of all skin pigmentations. Eyelid margin vascularization was less common in subjects with dark (n=21%) compared to light pigmentation (65%; =0.002), although the prevalence of MGD assessed via clinical evaluation did not vary significantly between those groups. Use of eyelid margin vascularization alone was not sensitive (33%) for MGD diagnosis. The sensitivity was 17% when limited to those with dark pigmentation. Our findings highlight the importance of gland expression and suggest limiting reliance on eyelid margin vascularization for MGD diagnosis, especially in those with dark eyelid skin pigmentation.