In this paper, we propose a hybrid level set model with application to the segmentation of eye socket. Compared with other level set methods, the hybrid model is more robust and accurate due to the combination of region and boundary information. It solves the leaking problem of boundary based level set method. The segment results of hybrid level set model can be used in 3-D eye socket reconstruction and calculation of hydroxyapatite implant, which are useful in computer-aided surgery. Experiments have shown that hybrid level set model has very good performance in the segmentation of eye socket.
Computer Graphics ; Humans ; Image Interpretation, Computer-Assisted ; methods ; Ophthalmologic Surgical Procedures ; instrumentation ; Orbit ; anatomy & histology ; diagnostic imaging ; surgery ; Surgery, Computer-Assisted ; Tomography, X-Ray Computed

PURPOSE: We explored the performance of and pressure elevation caused by small-diameter microtubes used to reduce overfiltration. METHODS: Using a syringe pump-driven constant-flow setting (2 µL/min), pressures were measured for polytetrafluoroethylene (PTFE) microtubes 5 mm in length with inner diameters of 51, 64, and 76 µm and for polyether block amide (PEBAX) microtubes with an inner diameter of 76 µm. Experiments (using microtubes only) were initially performed in air, water, and enucleated pig eyes and were repeated under the same conditions using intraluminal 9/0 nylon stents. RESULTS: The pressures measured in air in 51-, 64-, and 76-µm-diameter PTFE microtubes differed significantly (22.1, 16.9, and 12.2 mmHg, respectively; p < 0.001), and that of the 76-µm-diameter PEBAX microtube was 15.8 mmHg (p < 0.001 compared to the 12.2 mmHg of the 76-µm-diameter PTFE microtube). The pressures measured in water also differed significantly among the three microtubes at 3.9, 3.0, and 1.4 mmHg, respectively, while that in the PEBAX microtube was 2.6 mmHg (all p < 0.001). Using the intraluminal stent, the pressure in water of the three different PTFE microtubes increased to 22.6, 18.0, and 4.1 mmHg, respectively, and that in the PEBAX microtube increased to 10.5 mmHg (all p < 0.001). Similar trends were evident when measurements were performed in pig eyes. CONCLUSIONS: Although microtubes of smaller diameter experienced higher pressure in air, reduction of the inner diameter to 51 µm did not adequately increase the pressure attained in water or pig eyes. Insertion of an intraluminal stent effectively elevated the latter pressures. PEBAX microtubes created higher pressures than did PTFE microtubes.
Animals ; Disease Models, Animal ; Glaucoma/physiopathology/*surgery ; *Glaucoma Drainage Implants ; Intraocular Pressure/*physiology ; Ophthalmologic Surgical Procedures/*instrumentation ; *Polytetrafluoroethylene ; Prosthesis Design ; Swine

OBJECTIVEThis study is aimed at describing the clinical outcome of amniotic membrane transplantation for exposure of porous sphere implants.

METHODSA retrospective review of consecutive cases of porous sphere orbital implant exposure was carried out. Eight cases were presented between May 2004 and Oct. 2006 (5 males, 3 females; mean age 44.5 years). Six had enucleation and two had evisceration. Exposure occurred in two primary and six secondary. Orbital implant diameter was 22 mm in seven cases and 20 mm in one case. Six patients are with hydroxyapatite and two with high-density porous polyethylene (Medpor) orbital implants. The mean time from implantation to exposure was 1.1 months (range 0.8-2 months). All patients required surgical intervention.

RESULTSThe time of follow-up ranged from 3.0 to 28.0 months (mean 16.5 months). Amniotic membrane grafting successfully closed the defect without re-exposure in all of these patients. The grafts were left bare with a mean time to conjunctiva of about 1 month (range 0.8-1.5 months).

CONCLUSIONExposed porous sphere implants were treated successfully with amniotic membrane graft in all of patients. The graft is easy to harvest. This technique is useful, dose not lead to prolonged socket inflammation and infection, and it is valuable application extensively.

Adult ; Amnion ; transplantation ; Female ; Graft Survival ; Humans ; Male ; Middle Aged ; Ophthalmologic Surgical Procedures ; instrumentation ; methods ; Orbital Implants ; Prosthesis Implantation ; methods ; Retrospective Studies ; Treatment Outcome

PURPOSE: To evaluate the outcomes of surgery for Brown syndrome. METHODS: We reviewed the charts of 15 patients who underwent surgery for Brown syndrome. The limitation of elevation in adduction (LEA) ranged from -2 to -4 degrees. A superior oblique muscle (SO) tenotomy was performed in 4 patients, a silicone expander was inserted in the SO of 9 patients, and a SO recession was performed in 2 patients. The results of surgery were analyzed with a follow-up period of more than 6 months, 42.3+/-48.42 months on average. RESULTS: Nine female patients and 6 male patients with unilateral Brown syndrome were selected for this study. The left eye was the affected eye in 9 patients. The degree of preoperative LEA was -2 to -4 in 4 patients in whom SO tenotomy was performed, -3 to -4 in 9 patients treated with the silicone expander, and -2 to -4 in 2 patients treated with SO recession. The LEA was released after surgery in all patients without postoperative adhesion. However, unilateral overaction of the inferior oblique muscle due to excessive weakening of the SO occurred in 1 patient with tenotomy (25%) and in 1 patient with insertion of a silicone expander (11%). CONCLUSIONS: LEA was released after tenotomy, insertion of a silicone expander and recession of the SO in 13 of 15 patients with Brown syndrome. SO palsy due to overcorrection and under-correction with postoperative adhesion should be avoided.
Treatment Outcome ; Time Factors ; Syndrome ; Silicone Elastomers ; Prosthesis Implantation/instrumentation ; Ophthalmologic Surgical Procedures/*methods ; Oculomotor Muscles/physiopathology/*surgery ; Ocular Motility Disorders/physiopathology/*surgery ; Male ; Humans ; Follow-Up Studies ; Female ; Eye Movements/physiology ; Child, Preschool ; Child ; Adult