Central corneal thickness increases with age in cattle

The aim of this study was to identify the physiological reference values for central corneal thickness (CCT) and the age-related changes in CCT in healthy dairy cattle. The age of 50 dairy cows was recorded in days and the CCT values of both eyes were measured using an ultrasonographic pachymeter device. The mean age of the cows was 781.38 days and the mean CCT value was 799.44 mu m. There was a positive correlation between age and CCT (p<0.001, y = 751.34 + 0.0616x, R2=0.2104). Knowing the corneal thickness and age-related changes is important physiologically and pathologically. Medical treatment costs in eye diseases, injury due to extra procedure, decreased weight gain, decreased milk production and the transfer of animals that do not respond to treatment cause economic loss. In literature searches, no studies were found on this subject, except for a few studies (one of them postmortem) conducted about 25 years ago. The present study is the first study conducted on dairy cattle in the same environmental conditions in an organic farm. According to the presented study corneal thickness increases with age. In conclusion, corneal thickness in cattle changes over their lifetime and is similar to that reported in other mammals. Knowing the agerelated physiological change of corneal thickness has diagnostic, epidemiological and pathological importance.