Biometry of the ocular globe is an interesting technique in some cases: when one wants to compare the length of a globe with the fellow eye, to make the differential diagnosis between exophthalmia and buphthalmos; moreover, before implantation of an intrascleral prosthesis, completing the measurement of the horizontal diameter of the cornea.
Obviously, the eye of a pekinese dog is more bulky than a collie or a poodle eye.
Material and Methods
The equipment we used is an echograph machine specially dedicated to ophthalmology, the ULTRASCAN of Alcon Laboratory, with a 10 Mhz transducer for B mode echography, with possibility to perform A mode, alone or in conjunction with B mode.
The second transducer is an A mode biometry sound used only for biometrical measurements. We have compared the results of the two transducers: it appears clearly that the biometry sound gives better results, after many measurements, than the other one.
The animal is ever conscious or anaesthetized. In the first case, a topical anaesthetic drop is instilled on the cornea. We have mostly seize the opportunity of animals yet anaesthetized for a surgical problem, since the ocular movements are reduced or non-existent.
The biometry transducer is applied on the cornea, in the center, and in the optic axis of the globe. We make ten measurements for each eye, the machine gives directly the length of the anterior chamber, of the lens, of the vitreous chamber. It also gives the average of the length of the globe, which is the only one we consider in this enquiry.
We have a more important selection of dogs than of cats, so we shall not give the results we have got in this species, considering also that there is a great uniformity in the eye size in the cats.
All the results, with the averages, will be presented and discussed.