Causes and prognosis of neovascular glaucoma after pars plana vitrectomy in patients with diabetic retinopathy.

BACKGROUND

This study aims to investigate factors and prognosis of neovascular glaucoma (NVG) after pars plana vitrectomy (PPV) in patients with proliferative diabetic retinopathy (PDR).

METHODS

A total of 200 PDR patients with 225 eyes from May 2017 to January 2023 were retrospectively analyzed, including 115 males (128 eyes) and 85 females (97 eyes) with ages ranging from 30 to 75 years. All 25G PPV surgeries were completed by the same experienced chief physician. During the surgery, the anterior retinal fibrous vascular membrane was fully removed, and laser panretinal photocoagulation (PRP) was performed, phacoemulsification was combined in 114 patients. The average postoperative follow-up time was 10.65 ± 6.84 months and occurrence of NVG was recorded. Potential risk factors of NVG included age, glycated hemoglobin (HbAlc), blood urea nitrogen (BUN), severity of preoperative fundus lesion, preoperative treatment of anti-vascular endothelial growth factor (VEGF), preoperative PRP application, combination of phacoemulsification.

RESULTS

Among the total 225 eyes, 15 (6.7%) eyes developed NVG 1-12 months after surgery, including 11 cases within 6 months. Incidence of NVG was associated with age (t=-3.974), preoperative treatment of anti-VEGF (χ = 5.706), preoperative PRP application (χ = 4.744), comorbid tractional retinal detachment (TRD) (χ = 3.883), comorbid fibrovascular proliferation (FVP) (χ = 4.093), and combination of phacoemulsification (χ = 6.179), with all P values less than 0.05. On the other hand, no differences were found in HbAlc (t = 0.733) and BUN (t = 0.470), with both P values greater than 0.05. By the end of follow-up, all NVG cases after PPV underwent intravitreal injection of anti-VRGF drugs and supplementary retinal laser therapy, of which 8 patients had stable intraocular pressure control, 5 patients received drainage valve implantation surgery to control intraocular pressure, 1 patient abandoned surgery due to no light perception at presentation, and 1 patient underwent cyclophotocoagulation. The postoperative best corrected visual acuity (BCVA) after NVG was statistically significant compared with that before NVG (P < 0.05).

CONCLUSIONS

Occurrence of NVG in PDR was related to preoperative PRP and anti-VEGF, and might further have impact on prognosis. In addition, comprehensive consideration of patient's age, severity of preoperative fundus lesion and appropriate surgical method (i.e., whether combined with phacoemulsification) could be protective factors of NVG.

TRIAL REGISTRATION

ClinicalTrials.gov, NCT02399887, Registered 25 March 2019.