Ophthalmic imaging.

The availability of advanced imaging modalities in veterinary medicine has greatly widened the diagnostic imaging capabilities possible. Ultrasonography provides a rapid noninvasive modality that provides detailed examination and resolution of the intraocular structures and soft tissues surrounding the orbit of opaque eyes. Ultrasonography is cost-effective and widely available to practitioners,referral centers, and academic institutions. In many areas,mobile specialist ultrasonographers are available to supplement the equipment and skills of the practitioner. The added strengths of CT and MRI lie in their cross-sectional capability and better image quality. Unfortunately, the cost of CT and MRI currently limits their availability to referral centers and academic institutions. Primarily because of financial considerations, CT is currently more widely available for evaluation of equine disorders than MRI. A thorough evaluation of the multiple images and an understanding of normal anatomy and abnormal tissue patterns are indicated to maximize the use of each modality. Unlike ultrasonography, which can be performed in awake horses, the costs and contraindications of general anesthesia in some critical patients should also be considered when using CT and MRI. Finally, imaging artifacts are frequently encountered with each of these modalities. Thus, a thorough understanding of the various types of artifacts that occur is important so as to avoid interpretation pitfalls.