• corneal touch threshold;
  • dog;
  • intraocular pressure;
  • proparacaine;
  • rat


Objective  To determine the effect of 0.5% proparacaine in tonometry by evaluating corneal touch threshold (CTT) and intraocular pressure (IOP).

Animal studied  Nine rats (18 eyes, Sprague–Dawley) and 10 dogs (20 eyes, Beagle)

Procedures  The IOP and CTT were measured in each eye before and after topical anesthesia with 0.5% proparacaine. The IOP was evaluated using Tonopen for dogs and Tonolab for rats. The corneal sensitivity was evaluated by CTT through a Cochet–Bonnet aesthesiometer.

Results  The mean IOP was not significantly changed in rats or dogs before and after topical anesthesia. However, after application of proparacaine, CTT was significantly increased in both animal groups compared with that before application of proparacaine.

Conclusion  From this study, topical anesthesia was found to significantly lower the corneal sensitivity but have little effect on IOP measurements. In ophthalmologic examination, topical anesthesia can be used to reduce corneal sensation without an effect on IOP.