Diagnosis of postretinal blindness caused by intracranial disease in three dogs
Fonte: Joon-Young KIM
Findings of magnetic resonance imaging. A) A transverse T2-weighted image from case 1 showing hyperintense lesions in the right occipital region and midbrain. B) A transverse T2-weighted image from case 2 showing higher intensity in the left portion than in the right portion in the region of the optic chiasm. C) A sagittal postcontrast T1-weighted image from case 3 showing a homogeneous contrast-enhancing mass in the optic chiasm. D) A transverse T2-weighted image from case 3 showing a hyperintense lesion in the white matter and a mass in the optic chiasm region.
In this report, we provide clinical information on the diagnosis of postretinal blindness in veterinary ophthalmology. We have diagnosed three dogs with postretinal blindness (bilateral in one case and in the left eye in two cases). The electroretinogram results were normal and the optic axis was relatively clear in all cases. Our findings indicate that the reason for the blindness in these dogs was an intracranial lesion. Fundus photography did not reveal any significant changes, except in the optic disc. A normal optic disc, an optic disc that appeared to be smaller than that in the other eye, and a severely hyperemic and edematous optic disc were seen in cases 1, 2, and 3, respectively. On magnetic resonance imaging, two dogs had optic chiasm lesions (one a tumor, one inflammation) and the remaining dog had inflammation in the right optic tract and occipital lobe even though bright flash electroretinograms were normal. Magnetic resonance imaging and electroretinography can be used as diagnostic tools for detection and localization of central nervous system lesions in the visual pathways.