NASOLACRIMAL STIMULATION OF AQUEOUS TEAR PRODUCTION

Purpose. Aqueous tear production decreases after anesthetizing the ocu lar surface. Loss of the nasolacrimal reflex is a risk factor for neur otrophic keratopathy and keratoconjunctivitis sicca. The purpose of th is study was to evaluate the effect of nasal mucosal anesthesia on aqu eous tear production. Methods, Eleven healthy human volunteers with a normal ocular surface and Schirmer I tear-test scores >10 mm participa ted in this study. Schirmer I values were obtained daily for 3 days to establish a normal baseline. On a separate day, the right nasal mucos a was anesthetized with aerosolized 10% lidocaine (Xylocaine). After a 10-min period to allow the anesthetic to take effect and reflex teari ng to subside, the Schirmer I test was repeated. A saline nasal spray was used as a control. Results, Baseline Schirmer I values for both ey es had a mean of 22.98 +/- 1.05 mm (SEM). There was no difference in S chirmer scores between the two eyes after nasal anesthesia (p > 0.6); however, when these were compared with the baseline Schirmer I values, a significant decrease in tear production was noted (p < 0.001). The mean Schirmer I value after nasal anesthesia was 15.18 +/- 1.38 mm (SE M), a 34% decrease from baseline. The difference between the baseline and the normal saline control values was not significant (p = 0.160). There was a significant difference in Schirmer test scores between the saline control and nasal anesthesia groups (p < 0.02). Conclusions, I n addition to sensory neural stimulation from the ocular surface, sens ory stimulation of the nasal mucosa also promotes aqueous tear product ion. These results may help explain the decreased tear production obse rved in patients who have nasal mucosal damage, disease, or denervatio n.