Impairment of Lacrimal Secretion in the Unaffected Fellow Eye of Patients with Recurrent Unilateral Herpetic Keratitis

Purpose: To assess the impact of recurrent unilateral herpetic keratitis (HK) on the tear secretion of the unaffected fellow eye. Design: Prospective, noninterventional study. Participants and Controls: Thirty-five patients with a history of recurrent unilateral HK (clinically quiescent for at least 3 months) (HK group) and 35 patients who were age-and sex-matched with no history of corneal disease (control group). Methods: Tear osmolarity, tear instability (tear break-up time [TBUT]), tear reflex (Schirmer's I test), and central corneal sensitivity with the CocheteBonnet esthesiometer (Luneau, France) were measured in the HK and control groups. Main Outcome Measures: Tear osmolarity, TBUT, Schirmer's I, and central corneal sensitivity were compared between the affected and unaffected eyes of the HK and control groups. Results: Tear osmolarity and tear secretion reflex were similar between the affected and unaffected eyes of the HK group. Corneal sensitivity and TBUT were statistically lower in the affected eyes compared with the unaffected eyes in the HK group (P = 0.001 and P < 0.001, respectively). The central corneal sensitivity of unaffected eyes in the HK group was not significantly different from that in the control group (P > 0.05). The tear stability and tear secretion reflex were decreased and tear osmolarity was increased in the unaffected eyes of the HK group compared with the control group (P < 0.05, all cases). The difference between unaffected and control eyes varied according to the type of HK. All 4 tests were modified in patients with neurotrophic keratitis (KN). In the keratouveitis subgroup, only corneal sensitivity was normal, whereas Schirmer's I results were also normal in patients with archipelago keratitis. Tear osmolarity was consistently affected in both eyes of herpetic patients. Conclusions: Tear function is impaired in the unaffected eyes of patients with unilateral recurrent HK, even when the disease is apparently quiescent. The higher severity of results in the unaffected fellow eye of patients with KN in comparison with other herpes subgroups suggests that recurrent HK induces a reduction in the afferent pathways of the tear secretion reflex from the affected eye, leading to tear dysfunction in the unaffected eye.