Ultrasonographic and biometric evaluation of the eye and orbit of dogs.

The normal B-scan ultrasonographic anatomic features of the eye and orbit of mesocephalic and dolichocephalic dogs were described. The B-scan appearance of ocular and orbital structures correlated well with the visual morphologic features of the specimens. The eyes of mesocephalic and dolichocephalic dogs were measured by use of ultrasonographic methods; those measurements were compared with direct measurements of the specimens. The 2-tailed Student t-test was used for all statistical analyses (P = 0.05). Measurements made included mid-cornea to anterior lens surface, lens thickness, vitreous body (posterior lens surface to retina), and axial globe length. The A-scan measurements of all 4 ocular distances were significantly different, compared with direct measurements. The B-scan measurements of mid-cornea to anterior lens surface, lens thickness, and vitreous body were significantly different from direct measurements; however, there was no significant difference between B-scan and direct measurements of axial globe length. There was no significant difference between A- and B-scan measurements. These findings suggest that A- and B-scan measurements are similar and that B-scan measurements are reasonably accurate for axial globe determination. Several variables were compared by B-scan and direct measurement methods. The axial globe length of dolichocephalic dogs was significantly longer than that of mesocephalic dogs. The axial globe length of male and female dogs was not significantly different in mesocephalic or dolichocephalic dogs. There was no significant difference in the axial globe length of right and left eyes in mesocephalic or dolichocephalic dogs.