Measurement of corneal sensitivity in 20 ophthalmologically normal alpacas.

OBJECTIVE

To determine corneal sensitivity in 20 healthy adult alpacas (40 eyes) in order to establish reference values.

DESIGN

Prospective study.

ANIMALS

Twenty healthy, adult alpacas.

PROCEDURES

Corneal sensitivity was determined by the corneal touch threshold (CTT) using a Cochet-Bonnet esthesiometer. Five different regions of the cornea were evaluated (nasal, ventral, lateral, dorsal, and central).

RESULTS

Corneal touch threshold values (in mm filament length) obtained from five corneal regions demonstrated varying corneal sensitivities. The central region (34.5 ± 7.1 mm) was the most sensitive, followed by the ventral (29.5 ± 7.2 mm), medial (29.3 ± 7.3 mm), dorsal (25.6 ± 6.3 mm), and lateral (21.8 ± 5.7 mm) regions. All pairwise comparisons of regional differences were statistically significant (P < 0.05), except for the comparison between the ventral and medial regions (P = 0.88). Evaluation of the CCT while controlling for age (2-5 years vs. 6-10 years) demonstrated an increased CTT with an increasing age for the central, ventral, medial and lateral regions. A decrease in the CTT of the dorsal region was noted with increasing age.

CONCLUSION AND CLINICAL RELEVANCE

Corneal touch threshold values in 40 eyes of 20 healthy adult alpacas were determined using a Cochet-Bonnet esthesiometer. This study demonstrated the central corneal region to be most sensitive. Values obtained may serve as reference values in subsequent studies.