Procedures
cataract, depression, hemorrhage, retinal detachment
GROUP B, POSTOPERATIVE COMPLICATIONS, RETINA, CATARACT, HEMORRHAGE, LENS, PROLIFERATIVE, NEOVASCULARIZATION, SCLERA, VITREOUS HEMORRHAGE, RETINAL DETACHMENT, MACULAR EDEMA, LEAKAGE
The enrolled patients underwent a comprehensive ocular and general examination before surgery. Their detailed baseline information is shown in Table All operations were performed by two experienced fundus surgeons according to the relevant standardized procedures. Group A was treated with a 27G, 10,000 cuts per minute (cpm) beveled-tip vitrectomy system (27G Advanced Ultravit, CONSTELLATION Vision System, Alcon Surgical, Irvine, CA, USA), and Group B was treated with a 25G, 7500 cpm flat-tip vitrectomy system (25G Ultravit, CONSTELLATION Vision System, Alcon Surgical, Irvine, CA, USA). Three days before vitrectomy, the surgeons evaluated the patients’ fundus condition. If there was a massive vitreous hemorrhage, or dense neovascularization on the proliferative membranes or retina, the patients would receive anti-vascular endothelial growth factor (anti-VEGF) treatment. Then, during the operation, the surgical microscope combined with the wide-field contact lens provided fundus observation, with matching 25G or 27G fibre-optic light providing endoillumination. The surgeon inserted three trocars through the sclera 3.5 to 4 mm posterior to the limbus. Core vitrectomy was performed at the maximum cutting rate, an intraoperative pressure (IOP) of 25 mmHg, and aspiration pressure of 650 mmHg. Then, the peripheral vitreous was removed with scleral depression applied by an assistant. The surgeon removed the proliferative membrane with VP and microforceps to release the traction on the retina. During this process, the VP was set to the maximum cutting rate, and the IOP and aspiration pressure were adjusted according to the surgeon’s need. Typically, the aspiration pressure was maintained within the range of 300–600 mmHg. In the case of retinal detachment, the patient also underwent fluid-air exchange, and an appropriate endotamponade substance was used. For patients who required intravitreous silicon oil injection, the 25G CONSTELLATION® Vision System VFC Syringe (Alcon Surgical, Irvine, CA, USA) and the 27G VFI cannulas (MedOne Surgical, Inc in Sarasota, FL, USA) were utilized in the two groups separately. Intraoperative cataract surgery, retinal laser photocoagulation, electrocoagulation and other treatments were performed in accordance with the conditions of the patient’s lens and fundus. At the end of surgery, the surgeon decided whether to suture the incision based on the presence of leakage. After surgery, the patients with retinal detachment were advised to maintain a strict facedown position for 1 week.The operative efficiency was mainly determined by the total operation time, core vitrectomy time and productivity of cutting the membrane. The total operation time was defined as the time interval from the insertion of the first trocar to the closure of all the incisions. Core vitrectomy time was the time to clear the core vitreous within the visible range provided by the HR Direct 1X Lens (Volk ,Mentor ,OH ,USA). The productivity of cutting the membrane was quantified, and the method is shown in Fig. 
The retinal images captured during the surgery. (Patients were generally asked to follow up at 1 day, 1 week, 1 month, 3 months and 6 months after surgery. BCVA was tested using a standard visual acuity chart, and the measured decimal visual acuity was converted to (logarithm of the minimal angle of resolution) logMAR acuity. IOP was measured by a noncontact tonometer. In addition, patients underwent anterior segment and fundus examinations by slit lamp microscopy and indirect ophthalmoscopy for vitreous hemorrhage, retinal detachment and other postoperative complications. The surgeon recommended appropriate anti-VEGF or retinal photocoagulation treatment based on the presence of persistent macular edema, neovascularization or recurrent hemorrhage, if necessary.