Researchers at the Department of Small Animal Clinical Sciences, College of Veterinary Medicine, Michigan State University, explained in this informative study how analyzing the fundus allows the detection of diverse systemic diseases in animals.
The fundus is the inside, back surface of the eye that contains the retina and the optic nerve. This region facilitates a unique and noninvasive way to view blood vessels and nerve tissue inside the eye, making it valuable for uncovering underlying issues.
The examination is performed by dilating the pupil and using various instruments, including transilluminators, ophthalmoscopes, retinal cameras, and even smartphones, for a thorough assessment.
Changes in the appearance of retinal blood vessels and nerve tissue, such as color, diameter, outline, and tortuosity - a measure of the geometric complexity of a porous medium - can provide valuable diagnostic information about systemic diseases.
Various types of tumors can spread to the eyes, developing outcomes like retinal thickness, hemorrhages, inflammation of the uvea, and detachments. A large-scale retrospective analysis involving 233 dogs diagnosed with metastatic tumors revealed that approximately 11.6% of dogs had ocular metastases. By reviewing 173 cases of eye tumors in dogs, they concluded that approximately 26% were either metastatic or had spread to multiple locations within the body, with lymphoma and histiocytic sarcoma being the most common types, followed by hemangiosarcoma. Tumors reaching the subretinal space or entering through the optic nerve tend to be more advanced due to the protective barrier surrounding the retina, which can worsen the prognosis.
Examining the fundus should be considered an essential part of a thorough physical examination of animals. Various systemic conditions can manifest in the fundus, and understanding these manifestations can always aid in diagnosis and rapid treatment.
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