Corneoscleral Limbus in Glaucoma Patients: In Vivo Confocal Microscopy and Immunocytological Study

PURPOSE. To investigate morphologic changes of the corneoscleral limbus in glaucoma patients using laser scanning confocal microscopy (LSCM) and impression cytology (IC). METHODS. Eighty patients with glaucoma and 20 with dry eye were enrolled; 20 healthy subjects served as controls. Patients underwent the Ocular Surface Disease Index (OSDI) questionnaire, tear film break-up time, corneal staining, Schirmer test I, and LSCM of the limbus. Laser scanning confocal microscopy evaluated the limbal transition epithelium (LTE) regularity, dendritic cell (DC) density, and palisades of Vogt (POV). Impression cytology was performed and samples stained with HLA-DR and IL6. RESULTS. Glaucomatous patients were divided into three groups: Group 1 (40 eyes): one drug; Group 2 (20): two drugs; and Group 3 (20): three or more drugs. Limbal transition epithelium regularity was worse, and DC density higher in Groups 2, 3, and dry eyes compared with Group 1 and controls (P < 0.01). Preserved drugs worsened LTE regularity and induced higher DC density compared with preservative-free (PF) drugs (P = 0.041; P = 0.004). Despite typical POV architecture was preserved, signs of inflammation were found in glaucoma groups. HLA-DR and IL-6 positivity were higher in Groups 2, 3, and dry eye compared with controls (P < 0.001), and in preserved versus PF drugs (P < 0.05; P < 0.001). Dendritic cell density and LTE regularity correlated with HLA-DR, IL-6, and OSDI score in glaucoma groups and dry eyes (P < 0.001). CONCLUSIONS. Laser scanning confocal microscopy and IC documented antiglaucoma therapy induced morphologic alterations of limbus, which may play a role in the glaucoma-related ocular surface disease. Further studies are required to determine if limbal changes affect stem cell viability.