A narrative review on the association of high intraocular pressure and glaucoma in patients with retinal vein occlusion

Longitudinal changes in peri-papillary retinal nerve fiber layer thickness in patients with unilateral branch retinal vein occlusion

Background

Associations between retinal venous occlusion (RVO), elevated intraocular pressure, and glaucoma have been reported. Further investigations into structural alterations in the fellow eyes of individuals with unilateral RVO have revealed that the peripapillary retinal nerve fiber layer is thinner than in healthy eyes, suggesting that there may be systemic risk factors common to both RVO and glaucoma. We aimed to evaluate changes in peripapillary retinal nerve fiber layer thickness (pRNFLT) among individuals with unilateral branch retinal vein occlusion (BRVO).

Methods

This prospective observational study recruited 30 individuals (60 eyes) with newly diagnosed unilateral BRVO and macular edema, and a control group of 30 healthy individuals (30 eyes) with no abnormalities on fundus examination or concurrent systemic comorbidities. After baseline measurements, the participants were reassessed at 6, 12, and 24 months by measuring global and sectoral pRNFLT using spectral-domain optical coherence tomography.

Results

The mean age and sex distributions were comparable between the patient and control groups (both P > 0.05). When compared to fellow eyes, global and sectoral pRNFLT in eyes with BRVO were significantly higher at baseline (all P < 0.05). Over time, pRNFLT decreased dramatically, and by the conclusion of the two-year follow-up, there was a significant reduction from baseline in the affected eyes (all P < 0.05). Likewise, affected eyes experienced a significant improvement in best-corrected distance visual acuity and central macular thickness over the two-year follow-up (both P ≤ 0.001). Comparing the global and all-sector pRNFLT of fellow eyes in the patient group with those of normal eyes in the control group, there were no significant differences at any visit, except in the temporal sector, which revealed a significant reduction in pRNFLT at 24 months in the fellow eyes of patients with unilateral BRVO (P = 0.02).

Conclusions

Patients with unilateral BRVO experienced a significant reduction in pRNFLT in the affected eyes and, to a lesser extent, in the fellow eyes, compared with that of the control arm, suggesting that they are prone to retinal nerve fiber layer damage. The reduction in pRNFLT in the normal fellow eyes of patients with BRVO may be attributed to age or concurrent systemic comorbidities. Further studies with long follow-up periods are required to shed light on the etiology of functional and structural changes in both the retinal nerve fiber layer and ganglion cell complex in the normal and affected eyes of patients with unilateral BRVO.

The Association between Vascular Abnormalities and Glaucoma-What Comes First?

Glaucoma is a leading cause of irreversible blindness worldwide. While intraocular pressure (IOP) presents a major risk factor, the underlying pathophysiology still remains largely unclear. The correlation between vascular abnormalities and glaucoma has been deliberated for decades. Evidence for a role played by vascular factors in the pathogenesis of glaucomatous neurodegeneration has already been postulated. In addition, the fact that glaucoma causes both structural and functional changes to retinal blood vessels has been described. This review aims to investigate the published evidence concerning the relationship between vascular abnormalities and glaucoma, and to provide an overview of the "chicken or egg" dilemma in glaucoma. In this study, several biomarkers of glaucoma progression from a vascular perspective, including endothelin-1 (ET-1), nitric oxide, vascular endothelial growth factor (VEGF), and matrix metalloproteinases (MMPs), were identified and subsequently assessed for their potential as pharmacological intervention targets.

Outcomes of vitrectomy, complete pan-retinal photocoagulation, and endoscopic cyclophotocoagulation surgery after anti-VEGF treatment in neovascular glaucoma

Purpose

To establish a comprehensive treatment strategy and evaluate the efficacy of combination of anti-vascular endothelial growth factor (VEGF) injection, pars plana vitrectomy (PPV), endoscopic pan-retinal photocoagulation (PRP), and endoscopic cyclophotocoagulation (ECP) surgery for neovascular glaucoma (NVG) patients.

Methods

This retrospective study included 30 patients (30 eyes) who were suffering from NVG and treated with PPV & PRP & ECP (ECP group, 16 eyes), or Ahmed glaucoma valve implantation (Ahmed group, 14 eyes). The intraocular pressure (IOP), number of postoperative anti-glaucoma medications, best-corrected visual acuity (BCVA), successful rate of surgery, and postoperative complications were recorded and statistically analyzed at the time points of preoperative, 1-day, 1-month, 3-months, 6-months, and 12-months after operation.

Results

An obvious reduction in IOP and number of postoperative anti-glaucoma medications were observed in both the ECP group and Ahmed group after operation (P ​< ​0.05), and the ECP group showed a significantly lower IOP compared to the Ahmed group at the 6-months (P ​= ​0.014) and 12-months (P ​= ​0.047) postoperative time points, while there was no significant difference of medication number between the two groups except for 1-day after surgery. The BCVA showed no marked difference between the two groups preoperatively and postoperatively (P ​> ​0.05), while it was significantly improved in ECP group at 3-months (P ​= ​0.001), 6-months (P ​= ​0.004), and 12-months (P ​= ​0.010) time points comparing with preoperative BCVA. The surgical success rates in ECP group were also slightly higher than Ahmed group. And the complications after operation showed no marked differences.

Conclusions

The comprehensive treatment of PPV, endoscopic PRP, and ECP surgery for NVG patients after anti-VEGF injection can control IOP effectively and be friendly to patients' BCVA without obvious serious complications throughout a 12-months follow-up period.

Prediction model of contact forces and IOP during digital palpation of porcine eyes

Frequent intraocular pressure (IOP) measurements are desirable in the diagnosis and management of glaucoma. Most current tonometers utilize some form of corneal deformation to estimate the IOP, since trans-scleral tonometry suffers from loss of sensitivity. Tran-scleral and trans-palpebral tonometry, however, offer a pathway towards a non-invasive home tonometry. This article presents a mathematical model capturing the relationship between the IOP and the displacements imposed onto the sclera by externally applied forces. Similar to manual digital palpation tonometry, trans-scleral mechanical palpation makes use of two force probes that are advanced in a specific order and distance. Data from the applied forces and displacements, along with concurrent measurements of IOP is used to produce a phenomenological mathematical model. The experiments were carried out on enucleated porcine eyes. Two models are presented. Model 1 predicts IOP vs forces and displacements, while Model 2 predicts the baseline IOP (prior to applying the forces) as a function of the measured forces and displacements. The proposed models result in IOP errors of 1.65 mmHG and 0.82 mmHg, respectively. Model parameters were extracted using least-squares-based system identification methods. The results show that the proposed models can be used to estimate the baseline IOP with accuracy of ±1 mmHg over a pressure range of 10-35 mmHg, solely from measurement of tactile forces and displacements.

Retinal vein occlusions associated or complicated with glaucoma. Aspects of prediction and paths of progression

Background and Objectives: The aim of the study is to evaluate prediction factors and progression paths when retinal vein occlusions are associated with preexisting glaucoma or complicated with neovascular glaucoma. Materials and Methods: The study included 111 patients diagnosed with retinal vein occlusions, of whom 21 with preexisting open angle glaucoma and 12 with neovascular glaucoma as complication. The study was conducted from September 2020 to September 2022 in Timişoara, Romania. We assessed intraocular pressure, cup-disc ratio and retinal nerve fiber layer from the moment of retinal vein occlusion diagnosis until at least one year of follow-up, considering these aspects as values of prediction concerning the paths of progression when glaucoma and retinal vein occlusions come together. Results: The mean initial IOP for the affected eyes was higher (15.89 ± 2.73) than for fellow eyes (15.20 ± 3.11), with an increase of the IOP after one year, but with no statistically significant differences for the affected eyes (p=0.116) or for the other eyes (p=0.684), neither for the affected eyes associated with glaucoma in comparison with affected eyes without glaucoma association. The mean cup-disc ratio was higher for the affected eyes in comparison with the fellow eyes (0.4812 ± 0.219 for the affected eyes and 0.4738 ± 0.229 for the fellow ones in cases without associated glaucoma and 0.681 ± 0.157 for the affected eyes and 0.600 ± 0.241 for the fellow eyes in cases with associated glaucoma), with statistical significant differences in the evolution for both groups in comparison with the unaffected eyes (p=0.0056 for the first group and p=0.0003 for the second group). Comparing the evolution of the affected eyes with the preexisting glaucoma and the affected eyes without preexisting glaucoma, no statistical difference has been found (p=0.1104). The mean retinal nerve fiber layer decreased significantly in affected eyes without glaucoma (from 96 ± 14.71 to 89.16 ± 13.07) and in affected eyes with associated glaucoma (from 78.50 ± 4.23 to 75.50 ± 5.83), but with no significant differences (p=0.182). The level of decreasing was significantly more consistent in association with a venous occlusion (p= 0.0001). Conclusions: The findings of the current study fortify the correlation between glaucoma as a risk factor for retinal venous occlusion development, the intraocular pressure and optic nerve cupping as prediction factors in retinal venous occlusions, the association of a well-controlled preexisting glaucoma with no effect on the progression of the retinal venous occlusions and the development of a neovascular glaucoma with a much aggressive and different path of disease progression.