Tear film osmolarity in ocular mucous membrane pemphigoid.

Abstract

The aim of this study was to evaluate tear film osmolarity in patients with ocular mucous membrane pemphigoid (MMP). This observational cross-sectional study included 40 patients with biopsy-proven ocular MMP at Foster stage III referred to the tertiary-care Ocular Immunology and Uveitis Service at the San Raffaele Scientific Institute in Milan from June 2010 to August 2013. We evaluated the following clinical parameters: tear film osmolarity, ocular surface disease symptoms (OSDI) questionnaire, Schirmer test, tear film break-up time (TFBUT), and corneal and conjunctival staining. Forty patients (27 women and 13 men) were enrolled. All patients were undergoing systemic immunosuppressive therapy: 19 patients (47.5%) were on methotrexate, 9 (22.5%) were on mycophenolate mofetil, 9 (22.5%) were on low-dose corticosteroids, and 3 (7.5%) were on azathioprine. The mean osmolarity was 322.90 ± 33.39 mOsm/L, the mean OSDI score was 73.2 ± 17.9, the mean TFBUT was 6.60 ± 3.13 seconds, and the mean Schirmer test value was 4.07 ± 3.58 seconds. Tear film osmolarity significantly correlated with the TFBUT (r = 0.80; P < 0.0001), whereas no clinical correlation was found with the Schirmer test value (r = 0.01; P = 0.40) or with the OSDI score (r = 0.02; P = 0.29). Osmolarity did not turn out to be statistically different in the subgroups according to the Oxford corneal staining scale (P = 0.71) and to the Van Bijsterveld conjunctival staining score (P = 0.31). Tear osmolarity increased in patients with ocular MMP and correlated with the TFBUT. This result emphasizes the role of evaporative dry-eye condition in patients with ocular MMP. Tear osmolarity may be considered as a useful test in the diagnostic assessment of dry eye associated with MMP and for targeting therapeutic decisions.