Objective To observe serum homocysteine (Hcy) levels in retinal vein occlusion (RVO) patients with different ages and types.Methods A total of 79 patients (79 eyes) diagnosed with RVO were enrolled.There were 33 females and 46 males,the mean age was (57.00± 9.29) years.Eighty-two age-and sex-matched patients (82 eyes) without retinal vascular disease were included as controls.There were 32 females and 50 males,the mean age was (60.00± 10.15) years.Among RVO patients,there were 24 patients younger than 50 years old (young patients) and 55 patients older than 50 years old (elderly patients);35 patients with central RVO (CRVO) and 44 patients with branch RVO (BRVO).Fasting plasma Hcy,serum vitamin (Vit) B6,B12 and folate levels were measured in all patients.The relationship of high Hcy,low VitB6,low folate and RVO with different age were analyzed.Results Hcy level was significantly higher in RVO patients than control subjects (t =2.946,P ＜ 0.01).Blood concentration of folate and VitB6 were significantly lower in RVO patients than control subjects (t=2.641,2.889;P＜0.01).Blood level of VitB12 was significantly different in RVO patients from control subjects (t =1.665,P＞0.05).Concentrations of Hcy,folate,VitB12 and VitB6 were not different between patients with CRVO and BRVO (t =0.756,1.306,0.682,1.306;P＞ 0.05).Hcy level was significantly higher in the young RVO patients than in the elderly RVO patients (t=2.394,P＜0.05).Blood concentration of folate and VitB6 were lower in the young RVO patients than in the elderly RVO patients,but the difference were not significant(t=1.318,1.694;P＞0.05).The number of patients with high Hcy [x2=13.67,odds ratio (OR) =3.327,95％ confidence interval (CI) =1.742-6.354],low VitB6 (x2 =5.28,OR =2.068,95％CI=1.103-3.878) and low folate status (x2 =8.642,OR=2.546,95％CI=1.349-4.806) in RVO patients were more than control subjects (P=0.0001,0.023,0.004).Conclusions High Hcy,low folate and low VitB6 were risk factors for the onset of RVO.Hcy may play more important role in young patients with RVO.Hcy,folate and VitB6 levels were similar in CRVO and BRVO patients.

Ethical review is an important protective measure for research participants when conducting life sciences and medical research involving humans. "Exemption from ethical review" was proposed in The Measures for Ethical Review of Human Life Sciences and Medical Research Involving Humans issued in February 2023. To implement the exemption from ethical review within the permitted scope of laws and regulations, and to protect the privacy and rights of research participants when utilizing their data information and biological samples, multiple factors need to be considered, including the person responsible for exemption from ethical review, the conditions for exemption from ethical review, and the specific process for exemption from ethical review. As with other review procedures, exemption from ethical review also required the development of corresponding systems, implementation of responsibilities, and reliance on the construction of subject protection systems. It is hoped that this discussion can provide considerations for the implementation of exemption from ethical review.