Purpose: To compare nerve growth factor (NGF) levels in tears and on the ocular surfaces of normal control and non-Sjögren's type keratoconjunctivitis sicca subjects, and to investigate the effect of 0.1% prednisolone eyedrops on NGF levels in keratoconjunctivitis sicca patients.
Design: Prospective, double-masked, randomized, comparative clinical trial.
Participants: Forty-one keratoconjunctivitis sicca patients and 23 age- and gender-matched healthy subjects.
Methods: Baseline tear NGF levels were measured in keratoconjunctivitis sicca patients and healthy control subjects using enzyme-linked immunosorbent assays. Keratoconjunctivitis sicca patients received 0.1% prednisolone drops in one eye and 0.1% hyaluronic acid drops in the other, 3 times a day for 28 days. Also, impression cytology (IC) and immunostaining for NGF on conjunctival epithelium were performed on both groups.
Main outcome measures: Tear NGF/total tear protein (TP) concentration ratio, IC and NGF immunocytologic staining, subjective symptom scale, tear breakup time, and Schirmer values.
Results: Keratoconjunctivitis sicca patients were found to have baseline tear NGF concentrations higher than those of age- and gender-matched healthy control subjects (65.9+/-14.5 vs. 122.1+/-45.3 pg/mug, P<0.0001). In keratoconjunctivitis sicca patients, prednisolone treatment for 28 days resulted in a decrease in tear NGF levels, symptom scores, and IC scores, whereas hyaluronic acid treatment had no such effect (68.2+/-25.0 pg/mug vs. 108.0+/-43.4 pg/mug, P<0.0001 for tear NGF/TP ratio; 2.16+/-1.01 vs. 3.39+/-1.50, P = 0.0014 for symptom scale; 1.05+/-0.67 vs. 1.61+/-0.86, P = 0.0317 for IC). Measurements taken at both 14 and 28 days indicated that neither prednisolone nor hyaluronic acid treatment affected breakup time or Schirmer values.
Conclusion: Keratoconjunctivitis sicca patients showed elevated levels of tear NGF, which were decreased by treatment with 0.1% prednisolone. These data suggest that ocular surface NGF may play an important role in ocular surface inflammation processes associated with dry eyes.