Central corneal thickness in koi fish: effects of age, sex, body length, and corneal diameter.
OBJECTIVE
To establish the central corneal thickness (CCT) of normal koi fish by ultrasonic pachymetry, and its relationship to age, sex, body length and corneal diameter.


METHODS
Age, sex and body length of 33 koi fish (17 male and 16 female fish) were recorded. Horizontal and vertical corneal diameters of each eye were obtained using Jameson calipers. Central corneal thickness of all eyes was measured by ultrasonic pachymetry. Intraocular pressure (IOP) by rebound tonometry was obtained for a subgroup of nine koi (18 eyes).


RESULTS
Mean central corneal thickness was 325.9 microm. Central corneal thickness of female koi was greater than CCT of male fish (P < 0.01). Central corneal thickness increased with increasing age overall and within both sexes (P < 0.01). Central corneal thickness increased with increasing body length (P < 0.001). For male and female fish, CCT increased with increasing horizontal and vertical corneal diameters (P < 0.01). Mean horizontal corneal diameter (HCD) was 8.05 mm, mean vertical corneal diameter (VCD) was 7.38 mm, and HCD was consistently greater than VCD. Mean IOP of a subgroup of these koi was 4.9 mmHg by rebound tonometry.


CONCLUSIONS
Koi CCT increases with increasing age, body length and corneal diameter.
Lynch
Gwendolyn L
GL
Eye Care for Animals at City of Angels Veterinary Specialty Center, 9599 Jefferson Boulevard, Culver City, CA 90232, USA. gwendvm@yahoo.com
Hoffman
Allison
A
Blocker
Tiffany
T
D000367:Age Factors; D000818:Animals; D049628:Body Size; D003315:Cornea / Q000033:anatomy & histology*; D005260:Female; D005399:Fishes / Q000033:anatomy & histology*; D008297:Male; D012016:Reference Values; D012737:Sex Factors