Decreased substance P concentrations in tears from patients with corneal hypesthesia.

Abstract

To determine whether substance P concentrations in tears reflect corneal hypesthesia. Sixteen patients with unilateral corneal hypesthesia participated in this study. Unstimulated tears were collected from each eye of all subjects. Substance P concentrations in tears were measured by an enzyme immunoassay system. Substance P concentrations in tears from the affected eye were lower than those in tears from the unaffected eye in all subjects. The mean concentration of substance P in tears from affected eyes was 197.7 +/- 69.5 pg/mL, markedly lower than those from unaffected eyes (333.2 +/- 74.6 pg/mL). Substance P concentrations in tears, which are thought to reflect the neuropeptides levels in ocular tissues, can be used as an indicator of corneal denervation.