Reflex and steady state tears in patients with latent stromal herpetic keratitis.

Abstract

PURPOSE: To compare tear production in patients with stromal herpetic keratitis with that in healthy control subjects. METHODS: After instillation of 2 microL fluorescein into both eyes, the tear-fluorescein concentration was measured by fluorophotometry. During the first 10 minutes, steady state tear turnover (TTO-1) was determined. After a nasal alcohol stimulus to induce reflex tears, a second steady state tear turnover (TTO-2) was obtained during 15 minutes. The index of reflex lacrimation (IRL) was calculated as the percentage decrease in tear fluorescein concentration directly after the stimulus. TTO-1, TTO-2, and IRL were determined in the patients' affected eyes (n = 12), in the patients' healthy contralateral eyes, if possible (n = 9), and in one eye of healthy control subjects (n = 24). RESULTS: The TTO-1 in the affected and healthy eyes of patients was approximately two times lower than the TTO-1 in eyes of healthy control subjects (P = 0.012 and P = 0.024, respectively) and almost equal to the TTO-2 in eyes of healthy control subjects (P = 0.32 and P = 0.40). There were no significant differences in the values of TTO-1, IRL, and TTO-2 between affected and healthy eyes of patients (P > 0.5). IRL and TTO-2 did not differ significantly among the three groups (P > 0.5). CONCLUSIONS: Both eyes of the patients were dry. The dryness could be due to a defective reflex lacrimation under physiological conditions that can still be induced by nonphysiological nasal excitation. The cause of this may be demyelination of both trigeminal root entry zones as a result of a unilateral eye infection by the herpes virus. Another possibility is that dryness predisposes to herpetic infection or recurrent inflammation.