The occurrence of delayed ocular hypertension and glaucoma after pars plana vitrectomy for rhegmatogenous retinal detachment.

Abstract

Pars plana vitrectomy (PPV) has increasingly been used to treat rhegmatogenous retinal detachment (RRD). However, PPV potentially provokes ocular hypertension and/or glaucoma in the long term (Chang 2006; Wu et al. 2014; Toyokawa et al. 2015). The hypothesized mechanism is postoperative intra-ocular hyperoxygenation causing oxidative damage to trabecular meshwork and decreased aqueous humour outflow capacity (Chang 2006; Siegfried et al. 2010). The purpose of this study was to evaluate the occurrence of delayed ocular hypertension and glaucoma in patients who underwent PPV with gas for RRD because previous studies have not focused on this common subgroup specifically. This retrospective study was conducted at Departments of Ophthalmology, Medical University Graz, Austria, and University Hospital ‘Sveti Duh’, Zagreb, Croatia. The approval was obtained by the respective institutional review boards. Inclusion criteria were primary PPV with gas insufflation performed between January 2005 and May 2014, and a follow-up of ≥12 months. Exclusion criteria were bilateral PPV, retinal redetachment, history of ocular trauma or intra-ocular inflammation, pre-existing glaucoma or ocular hypertension, diabetic retinopathy or postoperatively initiated intravitreal treatment. Unoperated fellow eyes served as control group. Postoperatively all patients received combined topical cortisone and antibiotic therapy for 4 weeks in tapered frequency. Intra-ocular pressure (IOP) was measured with Goldmann applanation tonometry (Haag-Streit, Switzerland). Delayed ocular hypertension was defined as IOP≥24 mmHg on two separate postoperative visits occurring at least 2 months after PPV (Wu et al. 2014; Toyokawa et al. 2015). The results were presented as mean ± standard deviation (range). Kolmogorov–Smirnov test did not reveal normal distribution of IOP; therefore, Mann–Whitney U-test was used to compare intergroup differences. Statistical significance was defined as p < 0.05. Overall, 126 eyes of 63 patients could be enrolled forming the PPV group (n = 63) and the control group (n = 63). The patients' age was 59.2 ± 11.1 years (30–82). All patients were Caucasian. The follow-up averaged 31.6 ± 23.3 months (12–123). The final IOP was 15.9 ± 3.3 mmHg (9–23) in the PPV group and 15.2 ± 2.5 mmHg (10–21) in the control group (p = 0.250). In the PPV group, four eyes (6.3%) developed delayed ocular hypertension with a mean IOP of 26 ± 1.6 mmHg (24–28) occurring 8.5 ± 3.5 months (4–13) after PPV. The affected eyes were consequently treated with antiglaucoma agents. The final IOP averaged 18.8 ± 3.5 mmHg (15–23) in this subgroup. In one of these eyes (1.6%), notching of the superior disc rim was observed 19 months after PPV. On OCT, a corresponding thinning of the retinal nerve fibre layer in the superior segment was noted indicating preperimetric glaucoma (Fig. 1). In the control group, the IOP remained normal without administration of antiglaucoma agents and no suspect glaucoma signs were observed. Our study indicates that delayed ocular hypertension and subsequent glaucoma occur in 6.3% and 1.6% of eyes that underwent PPV with gas tamponade for RRD, respectively. The vitreous contains antioxidant ascorbate which consumes oxygen diffusing from retinal vessels before substantial amounts can migrate into the anterior chamber (Shui et al. 2009). After PPV intracameral hyperoxygenation occurs, where it provokes oxidative stress to the trabecular meshwork leading to some resistance of aqueous humour outflow (Chang 2006; Siegfried et al. 2010). Post-PPV glaucoma was shown to occur in up to 20% (Chang 2006). In contrast, others did not find glaucoma following PPV, but they observed associated late-onset ocular hypertension in 4.2% to 19.2% (Wu et al. 2014; Toyokawa et al. 2015). According to our findings, delayed ocular hypertension and glaucoma potentially occur also in patients who received PPV for RRD. The limitations of this study are the restricted number of enrolled patients and the weaknesses inherent to the retrospective study design. In conclusion, long-term IOP monitoring should be considered in patients who underwent PPV for RRD.