Effect of proparacaine on central corneal thickness values: An evaluation using noncontact specular microscopy and pentacam

PURPOSE: To study the effect of 1 drop of 0.5% proparacaine on central corneal thickness values monitored by nonspecular microscopy and Pentacam, a corneal topographer with rotating Scheimpflug camera. METHODS: Forty subjects were divided into 2 groups with 1 group measured with a noncontact specular microscope and the other group with Pentacam (Oculus, Inc., Wetzlar, Germany). One eye was randomly selected, and corneal thickness values were monitored every 30 seconds for 10 minutes. Baseline corneal thickness values were defined as the average of all measurements taken over 10 minutes. One drop of 0.5% proparacaine was instilled, and the corneal thickness values were monitored by the same instrument every 30 seconds for another 10 minutes after drug instillation. RESULTS: The 2 groups shared similar age range, refractive error, and baseline corneal thickness values. The spontaneous variation of corneal thickness values was within 3 μm for 10 minutes before drug instillation. There was no obvious trend of corneal thickness value change after the instillation of local anesthetics. The variation of corneal thickness values against the baseline was within 5 μm. CONCLUSION: One drop of 0.5% proparacaine does not produce any significant change in central corneal thickness.