Osmolarity of tears in eyes affected by recurrent herpetic stromal keratitis

Abstract

Abstract Purpose To assess the osmolarity of tears in eyes affected by recurrent herpetic stromal keratitis. Methods All the patients referred for a recurrent unilateral stromal keratitis infection by either Herpes simplex virus (VZV) or varicella‐zoster virus (VZV). All the patients have been finally tested for dry eye conditions when all clinical signs of ongoing keratitis had resolved. The osmolority was assessed using the TearLab® and then the corneal sensitivity was tested with the Cochet‐Bonnet esthesiometer (Luneau™). Values were compared using non‐parametric tests, and statistical significance was defined as p<0.05 (2‐tailed). Results Fifteen patients (mean age: 57 years +/‐ 11) were consecutively included in the study. The corneal sensitivity was strongly reduced in the affected side (9g/mm2 +/‐ 3.8) compared to the non‐affected side (0.55g/mm2 +/‐ 0.09, p=0.001). There was a trend (p=0.15) for a lower osmolarity in the affected eye (317.3 mosm/l +/‐ 6.2) compared to the non‐affected eye (321.2 mosm/l +/‐ 9.8), but the difference was not significant due to some affected eyes with high values of osmolarity. Indeed, we observed a relationship (p=0.1 for correlation test) between the loss of corneal sensitivity and the modification of tear osmolarity, with relative hypo‐osmolarity when corneal hyposesthesia was moderate and relative hyperosmolarity when corneal aesthesia was severly impaired. Conclusion This study suggests that recurrent stromal herpetic keratitis induces first an increase of tears production, as showed by hypo‐osmolarity with moderate relative hypoesthesia, and then a reduction of tears production when corneal sensitivity decreases below a threshold that remains to be more precisely defined.