Predictors of visual outcome after pars plana vitrectomy secondary to proliferative diabetic retinopathy.

Objective: Advanced proliferative diabetic retinopathy can lead to serious ophthalmological complications, including blindness. This research aimed to determine visual outcomes after pars plana vitrectomy secondary to proliferative diabetic retinopathy, as well as to identify its predictors. Methods: This prospective clinical study was performed in the Ophthalmology Clinic of the Clinical Centre University of Sarajevo. 60 subjects (eyes) with performed pars plana vitrectomy secondary to proliferative diabetic retinopathy were included in the study. Results: After univariate linear regression analysis, glucose, HbA1c, vascular endothelial growth factor, previous pan-retinal laser photocoagulation, baseline best corrected visual acuity, gas injection, vitreous haemorrhage, iris rubeosis, and glaucoma were found to be statistically significant parameters associated with postoperative visual outcome (p<0.05). Multivariate linear regression analysis was performed to evaluate the association between factors and postoperative best corrected visual acuity. Only intravitreal vascular endothelial growth factor concentration, previous pan-retinal photocoagulation, and gas injection remained statistically significant associated with postoperative best corrected visual acuity (p<0.05). Conclusion: Vitrectomy is an effective treatment for advanced proliferative diabetic retinopathy. Factors correlated with the better visual outcome are good systemic control, previous pan-retinal photocoagulation, low intravitreal vascular endothelial growth factor concentration, younger age, intraoperative internal gas tamponade, combined phacoemulsification and pars plana vitrectomy surgery, and the absence of postoperative complications. Abbreviations: PDR = proliferative diabetic retinopathy, VEGF = vascular endothelial growth factor, TDR = tractional retinal detachment, BCVA = best corrected visual acuity, DR = diabetic retinopathy, RDD = rhegmatogenous retinal detachment, NVG = neovascular glaucoma, BRVO = branch retinal vein occlusion, CBC = complete blood count, DBT = differential blood count, ESR = erythrocyte sedimentation rate, HbA1c = glycosylated hemoglobin, PHACO = phacoemulsification, ILM = internal limiting membrane, PPV = pars plana vitrectomy, IOP = intraocular pressure, PRP = pan-retinal photocoagulation, ETDRS = Early treatment diabetic retinopathy study.

Effect of pan-retinal laser photocoagulation on intravitreal vascular endothelial growth factor concentration in proliferative diabetic retinopathy.

Objective: This study aimed to determine the intravitreal concentration of VEGF in eyes with PDR and to evaluate the effects of previous PRP on its level. Methods: It was a cross-sectional study performed at the Clinical Centre University. It included 90 eyes surgically treated with PPV, divided into three groups, group A - patients with PDR with previous PRP, group B - patients with PDR without previous PRP, and group C - PPV performed due to the indication unrelated to diabetes. A vitreous sample was obtained during PPV, and the VEGF concentration was determined using an Enzyme-linked immunosorbent assay test (ELISA). Shapiro-Wilk, nonparametric tests Kruskal-Wallis, Mann-Whithney U test, ANOVA and Spearman's correlation test were used. Results: The highest vitreous VEGF concentration was in group B - 972.96 (743.33-1149.13) and was higher than in group A - 69.22 (37.33-225.15) and in group C - 19.93 (1.15-32.17) (p<0.001). There was a positive correlation between VEGF vitreous concentration and glucose level in group A patients (Rho=0.410; p=0.027). Conclusion: As a treatment before PPV surgery, PRP showed to be effective in the reduction of VEGF levels, which also highlighted a decrease in complications during and postoperatively. Abbreviations: DRS = Diabetic Retinopathy Study, PDR = proliferative diabetic retinopathy, VEGF = vascular endothelial growth factor, PRP = pan-retinal photocoagulation, PPV = pars plana vitrectomy, HbA1c = glycosylated hemoglobin, ETDRS = Early treatment diabetic retinopathy study, ESR = erythrocyte sedimentation rate, BCVA = best corrected visual acuity, OCT = optical coherent tomography, ILM = internal limiting membrane, PHACO = phacoemulsification, IOL = intraocular lens, ELISA = Enzyme-linked immunosorbent assay test, AUC = area under the curve, DME = diabetic macular oedema, TDR = tractional retinal detachment, VMT = vitreomacular traction.

Vitreous concentrations of vascular endothelial growth factor as a potential biomarker for postoperative complications following pars plana vitrectomy.

INTRODUCTION: The aim of the study was to investigate the effects of vascular endothelial growth factor (VEGF) concentration in vitreous on postoperative complications after pars plana vitrectomy (PPV). MATERIAL AND METHODS: Ninety subjects were surgically treated with PPV and followed up for 12 months at the Clinical Centre University Sarajevo, Clinic for Eye Disease. Exclusion criteria were presence of other eye diseases, systemic acute/chronic inflammatory conditions, or malignant neoplasms; previously performed PPV surgery; previously received intravitreal or systemic anti-VEGF therapy. A vitreous sample was obtained while performing the PPV procedure, using the Quantikine ELISA test to determine VEGF level, as a risk factor. Outcome measures were intraoperative and postoperative complications reported using categorical data: blunt and sharp dissection of membranes, intraoperative hemorrhage stopped by increasing infusion pressure, pressing with blunt instrument, or using diathermy. The following postoperative complications were assessed on the first day and at the 12-month follow-up visit: vitreous hemorrhage, fibrovascular proliferation (FVP), rubeosis iridis, and neovascular glaucoma (NVG). RESULTS: Levels of vitreous VEGF at the time of PPV were significantly higher in eyes with: vitreous hemorrhage on the first day after PPV (p = 0.003); FVP on the first day and 12 months after PPV (p = 0.002 and p < 0.001, respectively); iris rubeosis on the first day and 12 months after PPV surgery (p < 0.001, and p = 0.001, respectively); NVG on the first day and 12 months after PPV surgery (p = 0.043 and p = 0.011, respectively), compared to the eyes without complications. CONCLUSIONS: Preoperative levels of VEGF in vitreous can be a useful biomarker and predictor of the postoperative outcome in terms of intraoperative and postoperative complications.