Ischemic optic neuropathy and blindness after arterial occlusion for treatment of guttural pouch mycosis in two horses.

The study examines the occurrence of ischemic optic neuropathy and blindness in two horses after a surgical procedure to treat guttural pouch mycosis resulted in the occlusion of major arteries. The blindness was suspected to have been caused by retinal damage due to lack of blood supply, suggesting such complications can occur when all potential bleeding sources are occluded during the procedure.

Explanation of the Research

• The study primarily focuses on two cases of ischemic optic neuropathy in horses that were pursued for treatment of guttural pouch mycosis, a fungus-related disease. This condition had necessitated surgical intervention which entailed occluding (blocking) the external and internal carotid and greater palatine arteries.
• The method used is arterial occlusion, which is a common management strategy for treating guttural pouch mycosis. This disease affects the air-filled guttural pouch located in the horse’s head, and is characterized by a persistent and typically serious fungal infection.
• After the operation, the horses developed ischemic optic neuropathy, a condition where the optic nerve (the ‘cable’ transmitting visual information from the eye to the brain) doesn’t receive enough blood, thus becoming damaged. Consequently, the poor blood supply likely led to ischemic retinal damage, a condition where the retina (the light-sensitive tissue at the back of the eye) also doesn’t receive enough blood. These ischemic incidents led to an acute and unilateral type of blindness, meaning it occurred suddenly and in one eye. The research suggests the occlusion of major arteries was the cause.
• The study emphasizes that arterial occlusion is a recommended method for treating guttural pouch mycosis and it has been effective in managing the serious fungal infection. However, the research also raises concerns about the potential risks and side-effects of the procedure.
• Most notably, the study warns that if during the operation all possible sources of hemorrhage are occluded, this could lead to ischemia in the areas supplied by those arteries. These areas include essential parts of the eye, like the retina and the optic nerve. If these are not receiving adequate blood supply, retinal damage may occur, potentially resulting in blindness.