Background Orbital blow-out fracture often results in the abnormalities of appearance and function of eye.Because of the special and complex anatomical structure of orbital cavity,it is difficult to design and manufacture the corresponding orbital implants.The computer-aided designing and manufacturing (CADM) technology provides a new approach to orbital implants.However,the clinical value of this method is still under evaluation.Objective This study was to investigate the application and the therapeutic effect of CADM for orbital blow-out fracture.Methods The clinical data of 74 eyes of 74 patients who received surgery for orbital blow-out fracture from July 2006 to July 2012 in Henan Eye Institute,Henan Eye Hospital were retrospectively analyzed.Fiftyeight patients underwent CADM implanted surgery and 16 patients received non-CADM surgery in the same period with matched age,gender and lateral eyes in both groups.The individualized 3D orbital implants were designed and manufactured by the technology of CADM and then were implanted in the bone defects in the CADM group,while the traditional hydroxyapatite artificial bone or high density porous polyethylene material (Medpor) was utilized in the non-CADM group with a fellow-up duration for 22 to 69 months.The best corrected visual acuity (BCVA),eyeball exophthalmos,ocular position,eye movement,diplopia and postoperative complications were evaluated.Results The preoperative BCVA were 0.71±0.37 and 0.69±0.41,and the postoperative BCVA were 0.74±0.38 and 0.72±0.41 in the CADM group and the non-CADM group,respectively,showing an insignificant intergroup difference (Fgroup =0.043,P=0.837),but a significant variation was found over time (Ftime =13.576,P ＜ 0.01).The BCVA was significantly improved after surgery compared with before surgery in both groups (both at P＜0.05).No significantdifferences were found in the number of eyes with curative and improved diplopia and eye movement disorders between the two groups during the fellow-up duration (Z =-0.298,P =0.766;Z =-0.548,P =0.584).The preoperative eyeball exophthalmos values were (3.93±0.99)mm and (3.88±0.97)mm and the postoperative ones were (0.91 ±0.67)mmand (1.84±0.80) mm in the CADM group and the non-CADM group,respectively,without significant differencebetween the two groups (Fgroup =3.558,P =0.063).However,the eyeball exophthalmos values after operation wereremarkably lower than those before operation in both groups (both at P＜0.05).CT imaging displayed implants fitting well with fracture defect and attached to bone tissue accurately in all of the eyes in the CADM group,but in the nonCADM group,the bulge of implants damaging extraocular muscles or optical nerve was found in 2 eyes.No postoperative complication was seen throughout the fellow-up duration in the CADM group.Conclusions CADM technology for orbital blow-out fracture can reconstruct a 3D bony orbit and effectively repair ocular position and appearance,and furthermore restore eye movement and visual functions.The therapeutic outcome of CADM technology for orbital blow-out fracture is superior to conventional implants.