one eyes optic nerve is more damaged than the other, it will produce an important sign called an afferent pupillary defect.Defective light perception in one eye causes an asymmetrical pupillary constriction reflex called the afferent pupillary defect (APD). Arteritic PION
A-PION most commonly affects Caucasian women, with an average age of 73. At onset vision loss is unilateral, but without treatment it rapidly progresses to involve both eyes. Vision loss is usually severe, ranging from counting fingers to no light perception. Associated symptoms are jaw pain exacerbated by chewing, scalp tenderness, shoulder and hip pain, headache and fatigue. Perioperative PION
Vision loss is usually apparent upon waking from general anesthesia. Signs observable to a bystander include long surgery duration and facial swelling. Vision loss is usually bilateral and severe, ranging from counting fingers to no light perception. Cause
PION is a watershed infarction of the optic nerve that may cause either unilateral or, more often, bilateral blindness. PION typically occurs in two categories of people:
People who have undergone non-ocular surgery that is particularly prolonged or is associated with a significant blood loss. People who have experienced significant bleeding from an accident or ruptured blood vessels. In these cases, the person may develop anemia (too few oxygen-delivering red blood cells in the bloodstream) and often have low blood pressure as well. This combination can produce circulatory shock, and PION has sometimes been called shock-induced optic neuropathy.The combination of anemia and low blood pressure means that the blood is carrying less oxygen to the tissues.
The mean patient age was 62 years in one series (range 18 to 90 years).The mean age varies by etiology category; patients with giant cell arteritis (GCA) are older (mean 78 years, range 50 to 82 years), while those with PION in the setting of spine surgery are younger on average.There is a higher than expected prevalence of atherosclerotic risk factors and comorbid vascular disease, especially in patients with nonarteritic (idiopathic) PION, with 87 percent of patients having at least one risk factor for, or one other manifestation of, atherosclerotic vascular disease. While anterior ischemic optic neuropathy (AION) appears to be more common than PION after cardiac surgery, PION is relatively more common in cases of spine surgery. References
Further reading
Luneau K, Newman NJ, Biousse V (November 2008). "Ischemic optic neuropathies". The Neurologist. 14 (6): 341–54. doi:10.1097/NRL.0b013e318177394b. PMID 19008740. S2CID 8445417. Remigio D, Wertenbaker C (2000). "Post-operative bilateral vision loss". Survey of Ophthalmology. 44 (5): 426–32. doi:10.1016/S0039-6257(00)00107-7. PMID 10734242. Buono LM, Foroozan R, Savino PJ, Danesh-Meyer HV, Stanescu D (June 2003). "Posterior ischemic optic neuropathy after hemodialysis". Ophthalmology. 110 (6): 1216–8. doi:10.1016/S0161-6420(03)00257-4. PMID 12799249. == External links ==