Appliance of digital ultrasonic technique in canine cornea investigations

Abstract

The aim of this study was to adapt digital ultrasonic technique for corneal thickness investigation in the dog and evaluate corneal thickness changes after eyeball enucleation. Corneal thickness measurements, using digital ultrasonic technique, showed that the thickest cornea was in 10-15-day-old puppies, but there were no clear signal from the posterior surface of the cornea [corneal endothelium] in 10-15-days-old puppies as well as in 20-days-old puppies. In adult dogs this signal appeared very clear. The lens of young dogs is very close to the posterior surface of the cornea and this may be reason of such appearance. The increase on corneal thickness plays a significant role in cornea transplantation. Due to the linear relationship between hydration and corneal thickness, pachymetry provides information about the hydration status of the cornea. Our study of the cornea thickness changes after eyeball enucleation showed the increasing of corneal thickness in all point of the cornea in both eye. The graphic oscilograms of the cornea showed that 1-4 hour corneal signals amplitude changed marginally. Later the amplitude decreased. 5 hours after eyeball enucleation the secondary reflection appeared in the oscilograms. The low-key secondary reflection was shoed in the oscilogram of peripheral temporal point. The increase in corneal thickness is attributable to uptake of fluid, particularly on the stroma. Secondary reflection appeared in corneal oscilograms may show the changes of corneal stroma ultra structure. When cornea swells increased the diameters of collagen fibrils, changed the packing of the fibrils. But the large portion of the water goes not into interfibrilar space but into another space, such as lakes (region devoid of collagen fibrils). So we suggest that the corneal tissue can be taken for preservation till the 5th hour after the dog’s death. The ultrasonic investigation can be used as very informative and inexpensive method to evaluate cornea suitability for transplantation.