Clinical Analysis On Nonarteritic Anterior Ischemic Optic Neuropathy

Non-arteritic anterior ischaemic optic neuropathy (NAION) is the most common acute optic neuropathy in people aged 50 years and older. The condition is caused by infarction of the laminar or retrolaminar portion of the optic nerve head supplied by the short posterior ciliary arteries (SPCAs), which are branches vessel of internal of carotid artery. The underlying aetiology and pathophysiology of NAION is poorly elucidated. So far, few treatments with good results on NAION were reported. Moreover, there were not so much clinical studies about the relationship of NAION, carotid artery lesions and their relevant risk facors. The exact relationship among them is not clear.Objective1. To observe carotid atherosclerosis and carotid artery hemodynamics parameters changes of NAION patients and explore the relationship between NAION and carotid artery lesions.2. To evaluate cadiovascular risk factors on the impact of NAION patients and provide an objective basis for clinical treatment and prevention.MethodsData were collected from 30 patients (34 eyes) clinically diagnosed with NAION and 30 patients of age-matched non-NAION diseases (such as cataract without cardiovascular risk factors). Carotid artery color Doppler ultrasound examinations were employed to evaluate the hemodynamic parameters of carotid artery with measurement of cardiovascular risk factors including blood presure, blood glucose, blood lipid level, homocysteine, and so on.Statistical analysis was done by SPSS16.0 software. Intima-media thickness of carotid arteries, carotid atherosclerosis plaque between two groups was compared byχ2 test; Carotid artery stenosis between two groups was compared by Fisher's Exact Test; Internal carotid artery resistance index, carotid artery diameter, total cholesterol, triglyceride, low-density lipoprotein cholesterol, high-density lipoprotein cholesterol between two groups were compared by the two sample t-test; P <0.05 indicates the difference had statistical significance.Results1. 26 eyes (76.47%) accompanied with ipsilateral carotid atherosclerosis in NAION group, whereas 12 eyes (40.00%) in control group. Concerned with intima-media thickness of carotid arteries and carotid atherosclerotic plaque, there were 26 eyes (76.47%) and 18 eyes (52.94%) in the NAION group, there were 12 eyes (40.00%) and 7 eyes (23.33%) in the control group, the difference had statistical significance between two groups(χ2=8.788,5.869;P=0.003,0.015).Concerned with the vascular stenosis rate of carotid artery, the difference had no statistical significance between NAION group(only two eyes) and control group(none)(P=0.494).Concerned with the internal carotid artery resistance index, the difference had no statistical significance between NAION group (0.595±0.053) and control group (0.594±0.048) (χ~2=0.453, P=0.501). Concerned with the carotid artery diameter, the difference had no statistical significance between NAION group(4.871±0.756mm) and control group(5.127±0.657mm) (t=1.375,P=0.509) .2. In NAION group, 14 patients (46.67%) accompanied with hyperlipidemia; 6 patients (20.00%) with hypertension; 8 patients (26.67%) with type-2 diabetes. Hyperhomocysteinemia were found in 8/12(66.67%) NAION patients. There were 8 patients (26.67%) without hypertension, type-2 diabetes, hyperlipidemia, hyperhomocysteinemia and other systemic diseases.The levels of plasma total cholesterol (4.71±1.11mmol/L), triglycerides (1.98±1.01mmol/L), low-density lipoprotein cholesterol (2.75±0.81mmol/L) in NAION patients were higher than that in the control group (3.88±0.70mmol/L, 1.55±0.54mmol/L and 2.32±0.57mmol/L, respectively), the difference had statistical significance (t=3.468,2.027,2.342;P=0.047,0.021,0.045). Compared with the level of high-density lipoprotein cholesterol in the control group(1.12±0.22mmol/L),the cases in NAION group had higher leve(l1.05±0.20mmol/L), the difference had no statistical significance (t=1.291,P =0.377).Conclusions1. The pathogenesis of NAION is associated with intima-media thickness of carotid arteries and carotid atherosclerotic plaque. There were no similar reports in China.Carotid color Doppler ultrasound provided some basis for the diagnosis of NAION.2. Cardiovascular risk factors were associated with the episode of NAION; Maybe corresponding measures should be taken in prevention and treatment of NAION.