The purpose of this study was to evaluate the possibility of taking three-dimensional (3D) ultrasound images for better visualization of the feline eye and also taking the normal values of the optical long axis by using this technique.

A total of 16 (8 males and 8 females) previously healthy, 2-year-old cats. General Electric's Voluson Pro ultrasound equipment with "3D small parts" option of a 3D and 4D linear trapezoid 5–12 MHz transducer was applied for all the examinations. Ultimately the normal values of the optical long axis were measured from a line between cornea and optic disc in males and females, lefts and rights. All the obtained data were analyzed by paired sample t-test statistically.

The relationships and connections between vitreous membranous, retina, and ocular wall are finely displayed, and due to the stored 3D ultrasound tissue information, it was simple to be analyzed. The values of the optical long axis in obtained 3D images were measured. There was a significant difference between male and female dogs, but there was not any between left and right eye as it was expected (p<0/05).

The 3D data acquisition time required 5–10 seconds depending on the selected 3D box size of the interested region and also the desired image quality. This was also found in the cat, but a later independent study reported no significant difference. In veterinary medicine, ocular biometry can be used in establishing lens implant size, calculating lens power, and estimating prosthetic globe size after enucleation.