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The aim of this prospective cross-sectional cohort study was to clinically test whether corneal sensation decreases with age, based on subject feedback (psychophysical method), and whether it correlates with general pain perception.Methods: Subjects were recruited from 2 equally large age groups: group A (18-30 years) and group B (50-70 years; n = 45 per group). The inclusion criteria were healthy eyes, Ocular Surface Disease Index #13, and no contact lens wear. Corneal sensitivity threshold (CST) measurements were performed twice during each of the 2 visits, with the aid of the new Swiss liquid jet esthesiometer for corneal sensitivity (SLACS) and Cochet-Bonnet (CB) esthesiometer. A general pain sensitivity score was obtained from all participants.Results: Ninety subjects completed the study (n = 45 per age group, average age in group A: 24.2 6 2.94 years, group B: 58.5 6 5.71 years). Statistically higher CSTs for age group B were only observed for SLACS (mean difference: 1.58 dB, P , 0.001). No correlation was observed between the pain score and the CSTs obtained with either esthesiometry method (r = 0.11, P = 0.25 for liquid jet and r=20.076, P = 0.61 CB). Conclusions:A statistically significant decrease in corneal sensitivity was observed for the older age group with SLACS in this study, with CB however only a trend in the same direction was noted. General pain perception was not found to correlate with ocular surface sensation.

Purpose. The aim of the study was to test a newly developed prototype for corneal sensitivity measurement (liquid jet (LJ) with saline as stimulus) for repeatability and correlation with the Cochet-Bonnet esthesiometer (CB). This is an excerpt of a master thesis, which was part of a larger study Material and Methods. Corneal sensitivity thresholds (CST) were determined for 30 subjects, in a clinical trial with 30 subjects, with each device on two separate dates (with inter- vals of at least one day and a maximum of fourteen days). In addition, the pain sensitivity questionnaire (PSQ) was applied to determine any possible correlation with corneal sensitivity. Results. Similar standard deviations of the CSTs for LJ and CB were obtained (LJ (M ± SD): 24.3 ± 2.0 dB; CB (M ± SD): 20.0 ± 2.0 dB). No statistically significant difference in CST was found between the two visits for LJ (mean differen- ce: -0.063 dB, p = 0.78), however there was a statistically significant difference for CB (mean difference: -0.641 dB, p = 0.003). LJ CSTs correlated moderately positively with CB CSTs and PSQ (LJ-CB: r = 0.476, p < 0.001; LJ-PSQ: r = 0.437, p < 0.001). Conclusion. LJ offers a significantly larger stimulus bandwidth than CB. Better reproducibility was observed for LJ, while correlation between the results for the two instruments was good. Significant moderate positive correlation was found between LJ CSTs and general pain sensitivity. Keywords esthesiometry, Cochet-Bonnet, Liquid Jet, prototype, PSQ