Corneal esthesiometry in the healthy horse

To determine corneal sensitivity in healthy adult horses in order to establish reference values.

One hundred eyes of 50 healthy adult horses.

Corneal sensitivity was determined by evaluating the corneal touch threshold (CTT) in five different corneal regions using a Cochet-Bonnet esthesiometer.

Comparing CTT values (in mm filament length) of the five prescribed corneal regions revealed regional variations in corneal sensitivity, with the central region (21.15 +/- 6.23 mm) being the most sensitive, followed by the nasal (20.75 +/- 5.14 mm), temporal (20.70 +/- 5.37 mm), ventral (20.15 +/- 5.88 mm) and dorsal (15.85 +/- 3.70 mm) region. However, differences between the central, nasal, temporal and ventral regions were not statistically significant, whereas the dorsal region was significantly (P < 0.0001) less sensitive compared to the other regions. Division of the horses into three age groups revealed an insignificant decrease in corneal sensitivity with age in the nasal, temporal, ventral and central region, and an insignificant increase with age in the dorsal region. Correlation of corneal sensitivity with age was statistically significant in the central, ventral and temporal region. No statistically significant difference in the CTT was found between left and right eyes and between males and females.

CTT values in 100 eyes of 50 healthy adult horses evaluated with a Cochet-Bonnet esthesiometer generated reference values. Reference values are necessary to determine alterations of corneal sensation accompanying various eye diseases or systemic diseases.