ASSESSMENT OF THE TEAR FILM WITH TANDEM SCANNING CONFOCAL MICROSCOPY

Purpose: To evaluate the confocal microscopic appearance of the tear f ilm by correlating the interference pattern created by the lipid surfa ce with physiologic measurements of tear function and with clinic diag nosis. Methods. A series of 53 patients was examined with a battery of tests to evaluate the tear film and with confocal microscopy to evalu ate the interference pattern created by the lipid surface of the tear film. Assessment of the tear-film appearance involved five nonparametr ic scales: degree of debris in the tear film, variability of the inter ference pattern over time, linearity of the interference pattern, numb er of dry spots seen, and relative thickness of the lipid layer. For 1 0 other subjects, the confocal appearance of the tear film and evapora tion from the ocular surface was tested for before and after meibomian gland expression. Results, The confocal appearance correlated with mu ltiple physiologic variables and clinical diagnosis. Patients with seb orrheic meibomian gland dysfunction had a thicker lipid layer, greater variability, and more debris than did patients with obstructive meibo mian gland dysfunction. After meibomian gland expression, lipid thickn ess and linearity increased, whereas pattern variability and evaporati on decreased significantly. The mean reduction in evaporation was 48%. Conclusions, Confocal microscopy can be used to examine the tear film , and its appearance correlates significantly with physiologic variabl es in normal individuals and in disease states. The confocal appearanc e of the lipid interference patterns and evaporation from the ocular s urface are altered after lipid expression from meibomian glands.