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.
Pulmonary capillary hemangiomatosis (PCH) is a disease affecting the blood vessels of the lungs, where abnormal capillary proliferation and venous fibrous intimal thickening result in progressive increase in vascular resistance. It is a rare cause of pulmonary hypertension, and occurs predominantly in young adults. Together with pulmonary veno-occlusive disease, PCH comprises WHO Group I causes for pulmonary hypertension. Indeed, there is some evidence to suggest that PCH and pulmonary veno-occlusive disease are different forms of a similar disease process. Presentation
These are non specific. Typical symptoms include dyspnea, cough, chest pain and fatigue. Genetics
At least some cases appear to be due to mutations in the eukaryotic translation initiation factor 2-alpha kinase 4 (EIF2AK4) gene. Diagnosis
Lung biopsy is essential to make this diagnosis. This can be difficult if the pulmonary pressure is high. Investigations
Chest X ray may show enlargement of the heart and ill-defined patchy lesions in the lung fields. CT chest typically shows wide spread ill-defined centrilobular nodules of ground glass opacity. This is a nonspecific finding and may be seen in a number of pulmonary diseases. CT pulmonary angiography usually shows enlargement of the main pulmonary artery. When measured by echocardiography or pulmonary angiography, the pulmonary arterial pressure is typically elevated. Differential diagnosis
Pulmonary veno-occlusive disease

Associations
This condition has been reported in patients with Ehlers Danlos syndrome, CREST syndrome and scimitar syndrome. Treatment
The only definitive treatment for this condition currently is lung transplantation. Median survival without treatment is 3 years.Imatinib may be of use.Epoprostenol does not appear to be of use.