Abstract
Purpose :
Corneal sensitivity is an important factor in several ocular and systemic conditions, however, current measurement methods for corneal touch sensitivity are rather complicated and impractical to use. In a prospective clinical study, we evaluated a novel type of rebound technology based esthesiometry (RTE).
Methods :
One hundred and eight subjects with mean age of 51,5 years (SD 18,2) were included in the study. The method used was a rebound technology-based prototype instrument employing a lightweight probe driven by a magnetic field. The corneal sensitivity of the subject was assessed by establishing the minimal perceivable kinetic energy probe velocity touching the center of the cornea for about 2 milliseconds. Test subjects used trigger button to report sensation. The stimuli were implemented in linear increments, starting with 0.67 µJ and ending with 26.01 µJ of energy (on average), in 10 steps, where velocity of the probe, the impact level, was linearly scaled. Thresholding algorithm was set to increase the stimulus intensity gradually, then to assess the final threshold by bracketing up and down. The final result was defined as the lowest intensity of the probe to which participants responded successfully twice. Classic Cochet – Bonnet (C–B) esthesiometer was used for comparison.
Results :
All 216 eyes were successfully measured from which 26 exceeded the measuring range of the RTE and were excluded from the results. Average measured corneal sensitivity with the RTE was at the level of 3.4 µJ (SD 5.4 µJ) and with the C–B esthesiometer, 54.7 mm (SD 8.8 mm). The correlation of both types of measurements was r = -0.70 at significance level p < 0.001. The average within-subject deviation of the positive responses around the threshold obtained with RTE was 0.98 µJ. Dividing measurements to normal versus decreased corneal sensitivity using cut-off values of 56 mm (C-B) and 1.0 µJ (RTE) resulted in agreement between the two methods in 83 % of tested eyes.
Conclusions :
We propose a novel method for corneal esthesiometry using rebound technology which could represent a practical and reliable way of measuring the corneal touch sensitivity in a clinical practice.
This is a 2021 ARVO Annual Meeting abstract.