This was a retrospective, comparative and non-randomized study, in line with the principles of the Helsinki Declaration, and was approved by the Ethics Committee of the First Affiliated Hospital of Shenyang, China Medical University. We reviewed the medical notes of 63 patients with PDR who underwent vitrectomy with or without pretreatment as a result of non-absorbent VH between January 2013 and December 2015 and who completed at least 6 months of follow-up. Patients were divided into the IVR group and the control group according to whether an intravitreal injection of ranibizumab (IVR) was administered before surgery. In the control group, 32 patients received vitrectomy only from January 2013 to December 2014; 31 patients in the IVR group underwent vitrectomy from January 2015 to December 2015. Pre-IVR pretreatment, all participants signed an informed consent form explaining the benefits and risks prior to surgery.
All patients underwent a comprehensive examination with the best-corrected visual acuity (BCVA), intraocular pressure (IOP), B-ultrasound, slit lamp biomicroscopy and 90D Non-Contact Slit Lamp Lens. During follow-up, macular edema was measured by fundus photography, optical coherence tomography and fluorescein angiography (FFA).
The inclusion criteria were as follows: (1) patients with PDR and moderate vitreous haemorrhage (only disc faintly visible) and severe haemorrhage (no fundus view) was selected as the study object; (2) patients with type 2 diabetes aged at least 50 years old (according to the American Diabetes Association or World Health Organization guidelines) and preoperative haemoglobin A1c at most 10%; (3) non-clearing vitreous haemorrhage within 1 month secondary to PDR; (4) the diagnosis of macular edema dependent on the presence of apparent retinal thickening or lipids in the posterior pole seen by the surgeon during vitrectomy. The severity was classified on the basis of the International Clinical Diabetic Retinopathy and Diabetic Macular Edema Disease Severity Scales : mild—partial retinal thickening or hard posterior pole exudation but away from the centre of the macula; moderate—retinal thickening or hard exudation close to the centre of the macula but not involved in the centre; and severe—thickening of the retina or hard exudate involving the centre of the macula; (5) during the follow-up period, the DME severity grading standard was examined by fundus photography and FFA: (1) no obvious DME—no obvious retinal thickening or hard exudation at the posterior pole; (2) mild DME—thickening or hard exudation of the retina in the posterior pole away from the centre of the macula; (3) moderate DME—retinal thickening or hard exudation near but not involving the macular centre; and (4) severe DME—retinal thickening or hard exudation involving the macular centre. The exclusion criteria included (1) history of vitrectomy, other intraocular surgery and ocular trauma; (2) complete PVD and an anterior macular membrane; (3) retinal detachment traction (tractive, rhegmatogenous or exudative), macular disease secondary to the outer membrane of the retina, retinal vein occlusion, optic neuropathy and other serious eye diseases; (4) history of laser or anti-VEGF injection; (5) DM accompanied by severe cardiovascular and cerebrovascular diseases, abnormal liver or kidney function and other systemic diseases; (6) coexisting ocular disease caused by macular edema (e.g. branch vein occlusion or central retinal occlusion); and (7) follow-up period less than 6 months.
One surgeon (Na Cai) with over 20 years of experience in posterior segment surgery performed all injections and surgeries. Patients in the IVR group were intravitreally injected with ranibizumab (0.5 mg/0.05 ml) 3 days before PPV and stripped. Ranibizumab was aspirated into a 1-ml syringe and injected into the vitreous cavity through a 30-gauge needle . All patients underwent standard three-hole 20-gauge pars plana vitrectomy (PPV). The procedures included the removal of the anterior and central vitreous and the vitreous cortex; detachment of the posterior hyaloid created by suction with the vitrectomy instrument; the removal of proliferative membranes with intraocular forceps; endodiathermy or increased infusion pressure used to stop intraoperative bleeding; and ILM peeling performed with ILM forceps by using a continuous curvilinear capsulorhexis technique without staining of the ILM. The ILM was moved and extended approximately 6-disc diameters horizontally and from the upper arcade to the lower arcade vertically around the fovea. All patients underwent intra-retinal laser photocoagulation. All phacoemulsification procedures were performed with phacoemulsification, and intraocular lenses were implanted to avoid the development of cataracts. Finally, C3F8 gas or silicone oil (SO) was used when needed at the end of the operation. Subconjunctival injections of dexamethasone (2 mg), topical antibiotics and corticosteroid drops were administered postoperatively.
The primary outcome measures after vitrectomy included the BCVA, comparison of visual acuity improvement, and CMT. The secondary outcome measures included intraoperative bleeding, required internal diathermy frequency, need for tamponade, operative time, number of iatrogenic retinal breaks, and postoperative complications.
To compare the similarities between the two groups, we scored vitreous haemorrhage from 0 to 3 , (0—none, clear field of view; 1—mild, visible fundus details but difficult to assess retinal nerve fibre layers or small blood vessels; 2—moderate, only the intervertebral disc was faintly visible; and 3—severe, fundus details were invisible). The severity of intraoperative bleeding was defined as follows: mild bleeding, spontaneous or stopped with a litre bottle; severe bleeding, covering half or more of the posterior pole, required intra-arterial diathermy treatment . We considered recurrent vitreous haemorrhage (VH) as grade 1 or higher VH occurring more than 1 week after surgery. If the incidence rate was 4 weeks or less, it was considered early recurrent VH; otherwise, it was considered late recurrent VH .
The baseline characteristics of patients were collected and analysed using SPSS version 22 (IBM, Armonk, NY, USA). The Snellen visual acuity was converted to logarithm of the minimum angle of resolution (logMAR) units for statistical analyses. Student’s t test was used for pairwise comparisons of age, duration of diabetes, BCVA, IOP, CMT and mean surgical time between the two groups. The results are presented as the mean and standard deviation. The chi-square test or Fisher’s exact test was used to analyse differences in sex, intraoperative bleeding, the incidence of iatrogenic retinal breaks, the use of endodiathermy and SO endotamponade, vitreous haemorrhage score and grade of ME. One-way analysis of variance (ANOVA) was used to evaluate BCVA at follow-up and baseline stages. P < 0.05 was set for statistical significance. Improvement or reduction in BCVA was defined as two or more change lines; otherwise, BCVA was defined as unchanged. The Mann–Whitney U test was used to determine whether there was a significant difference in visual improvement between the two groups.