BACKGROUND: There are two commonly used techniques of primary orbital implant placement, one is using sclera to cover hydroxyapatite prosthesis after evisceration and the other is using sclera to wrap around the hydroxyapatite prosthesisafter enucleation, which one is more efficient and safer.OB.IECTIVE: To compare the clinical safety of the two kinds of surgery for placing hydroxyapatite prosthesis in the orbit.DESIGN, TIME AND SETTING: A retrospective case analysis was performed.between June 2000 and June 2005 at Xiangya Hospital, Central South University, Changsha, Hunan Province, ChinaPARTICIPANTS: Fifty eyes of 50 cases who were admitted between June 2000 and March 2003 to accept enucleation implants, including 39 cases with atrophic eyeball, 6 cases with anterior scleral staphyloma, 1 case with absolute glaucoma, 4cases with eyeball rupture. Forty-nine eyes of 49 cases who were admitted between April 2003 and June 2005 to accept evisceration implants, including 36 cases with atrophic eyeball, 8 cases with anterior scleral staphyloma, I case with absolute glaucoma, 4 cases with eyeball rupture. All the operations performed by the same surgeon.METHODS: In enucleation implant group, autologous sclera-wrapped hydroxyapatite orbital implant was placed into the muscle cone after enucleation. In evisceration implant group, the bared hydroxyapatite orbital implant was placed into muscle cone after evisceration, and was covered by autologous sclera in anterior.MAIN OUTCOME MEASURES: Appearance improvements and complications of patients after orbital implant placement. RESULTS: There was no significant difference between the two groups in appearance improvement. In enucleation implant group, 7 patients experienced conjunctival dehiscence and 5 patients experienced orbital implant exposure. In evisceration implant group, no conjunctival dehiscence and orbital implant exposure occurred. There were significant differences between the two groups in conjunctival dehiscence ( x2 =7.380, P < 0.01) and orbital implant exposure( x2 =5.160, P < 0.01 ).CONCLUSION: Evisceration with sclera-covered orbital implant is more simple, safe, convenient and effective than enucleation with sclera-wrapped orbital implant.