Abstract： Objective To investigate the characteristics and risk factors of biological ocular structures in the development of diabetic retinopathy in diabetes mellitus (DM) patients.Methods Retrospective case series study.Systemic condition,results of laboratory examination,fundus examination,refractive status and ocular biometry measured by IOL Master,were collected from the DM group(118 type-Ⅱ diabetic patients with diabetes more than 10 years) and the control group (50 cataract subjects without diabetes).The DM group was classified to three subgroups:none diabetic retinopathy,minimal and moderate nonproliferative diabetic retinopathy (NPDR) and vision-threatening diabetic retinopathy.Chisquare and Kruskal-Wallis rank sum tests were used to compare the difference between the DM and control groups.Ocular biometry,including axial length (AL),anterior chamber depth (ACD),corneal diameter,corneal curvature and spherical equivalent refraction (SE) were analyzed with multivariate logistic regression.Results 1.There was no significant difference in systemic factors.2.Ocular factors:There were significant differences of AL and ACD between the DM and control groups.The risk for the development of DR and the severity of DR were increasing with shorter AL and ACD between the three DR subgroups,especially the risk of and the occurrence of macular edema (ME) (OR =16.869,7.248,6.577 ;P ＜0.05,respectively).3.The risk of advanced DR increased significantly in hyperopia (OR =1.301,95％ CI =1.044 to 1.621 ;P ＜ 0.05).Conclusions The ocular risk factors of type-Ⅱ DM patients with diabetes more than 10 years are the AL and ACD,which have significant relationship with the development and the progress of DR.