Electrophysiological evaluation and visual outcome in patients with central retinal vein occlusion, primary open-angle glaucoma and neovascular glaucoma

Anterior segment features in neovascular glaucoma: An ultrasound biomicroscopy study

PURPOSES

To investigate the features of the anterior segment structures in neovascular glaucoma (NVG) and analyze its differences from primary angle-closure glaucoma (PACG).

METHODS

This study included patients who were first diagnosed with monocular NVG and PACG at the Affiliated Eye Hospital of Nanchang University during August 2019 to June 2022. Ultrasound biomicroscopy (UBM) was used to measure the anterior segment parameters of those eyes, including anterior chamber depth (ACD), anterior chamber width (ACW), anterior chamber area (ACA), iris area (IA), maximum iris thickness (ITMAX), middle iris thickness (ITMID), iris curvature (IC), lens vault (LV), angle opening distance (AOD500), trabecular iris angle (TIA500), trabecular-iris space area (TISA500) and peripheral anterior synechia (PAS) length.

RESULTS

In this study, paired samples t-test showed that IA [1.170(0.324) mm2], ITMAX [0.368(0.079) mm], ITMID [0.280(0.062) mm] and IC [0.147(0.037) mm] of NVG were smaller than F-NVG [2.058(0.195) mm2, 0.611(0.045) mm, 0.415(0.049) mm and 0.272(0.077) mm], the AOD500, TIA500, and TISA500 of NVG were also smaller than F-NVG. Independent samples t-test showed that ACD [2.349(0.350) mm] and ACA [16.326(3.547) mm2] of NVG were larger than PACG [1.971(0.240) mm, 12.030(1.860) mm2], but the IA [1.170(0.324) mm2], ITMAX [0.368(0.079) mm], ITMID [0.280(0.062) mm], IC [0.147(0.037) mm] and LV [0.436(0.172 mm)] were smaller than PACG [1.740(0.294) mm2, 0.548(0.084) mm, 0.404(0.065) mm, 0.283(0.060) mm and 0.737(0.196) mm]. Among the 16 patients with 360° angle-closure NVG, the PAS length was 0.834 (0.326) mm, which exceeded the Schwalbe line.

CONCLUSION

In NVG, the iris is atrophied, thinned, and straight, while the ACD is normal or slightly shallow. In 360° angle-closure NVG, the PAS length exceeds the Schwalbe line, presenting a pseudo angle phenomenon and a hockey stick sign. Notably, the anterior segment structure morphology of NVG exhibit differences from those of PACG.

The progress of assessment methods and treatments of neovascular glaucoma secondary to central retinal vein occlusion

Neovascular glaucoma is a condition that results from central retinal vein occlusion and often leads to blindness. Accurate evaluation and appropriate treatment are crucial for patients. However, there is currently no uniform and clear standard to differentiate between ischemic and non-ischemic central retinal vein occlusion. Also, the assessment of neovascular glaucoma progression is uncertain. Meanwhile, although pan-retinal photocoagulation is a standard treatment to prevent the onset of neovascular glaucoma, its actual efficacy and the timing of intervention remain highly controversial. It is still challenging to balance the risks of side effects in the visual field against the uncertain effectiveness of the treatment. This paper delves into the pathogenesis of neovascular glaucoma to understand the development of therapeutic approaches. By taking into account various assessment criteria of central retinal vein occlusion and neovascular glaucoma over the years, combining functional tests and morphological tests provides the most accurate and rigorous solution. The age of patients, the extent, location, and duration of retinal ischemia are the primary factors that affect the severity and extent of ischemic central retinal vein occlusion and induce serious complications. From the perspective of prevention and treatment, the ischemic index is closely related to the development of neovascularization. The paper provides essential insights into the mechanism, efficacy, complications, and optimal timing of pan-retinal photocoagulation. Comparing the treatment effects of pan-retinal photocoagulation and intravitreal anti-VEGF injections, we suggest a combination of both treatments to explore effective treatment with fewer side effects in the long term. This article details the debate on the above issues and explores ideas for the clinical diagnosis and preventive treatment of neovascular glaucoma that results from ischemic central retinal vein occlusion.

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

BACKGROUND AND OBJECTIVE

Retinal vein occlusion (RVO) is a major cause of vision loss and elevated intraocular pressure (IOP), high ocular perfusion pressure, and glaucoma are known ophthalmic risk factors for RVO. The aim of this paper is to provide the update on the association and management of high IOP/glaucoma and RVO.

METHODS

A literature review was performed in PubMed and Medline until May 2022 utilizing specific keywords and cross-matched reference lists.

KEY CONTENT AND FINDINGS

The association of RVO with high IOP/glaucoma may be attributed to retinal ganglion cell loss due to retinal ischemia in high IOP and glaucoma. As new modalities showed, decreased optic disc perfusion, reduced density of blood vessels in the optic nerve head of glaucoma patients, changes in the peripapillary microvascular parameters, and decreased retinal nerve fiber layer (RNFL) thickness of the optic nerve head of eyes with RVO suggest a common pathway between RVO and glaucoma. Literature suggests the close follow up for glaucoma development among patients with non-arteriovenous (AV) crossing (optic cup or optic nerve sited) RVO in fellow eye and management of elevated IOP among RVO cases treated with anti-vascular endothelial growth factor (VEGF) antibodies/corticosteroids and those with preexisting primary open angle glaucoma (POAG).

CONCLUSIONS

Determining potential patient responses to treatment and considering therapeutic options are challenging among patients with RVO and glaucoma. However, IOP lowering managements in preventing IOP spikes in patients with preexisting glaucoma and early treatment of macular edema in eyes with RVO is recommended.

Central Retinal Vein Occlusion in Younger Swedish Adults: Case Reports and Review of the Literature

Purpose:

To investigate associated systemic diseases, other conditions, visual outcome, ocular complications and treatment in Swedish patients younger than 50 years with central retinal vein occlusion (CRVO) and reviewing the literature.

Methods:

Twenty-two patients with CRVO, younger than 50 years, were examined with full-field electroretinography (ERG) within 3 months after a thrombotic event, or were periodically examined and were observed for at least 6 months. In 18 of these patients, the initial retinal ischemia was studied using the cone b-wave implicit time in the 30 Hz flicker ERG. Fifteen patients also underwent fluorescein angiography. Optical coherence tomography (OCT) was performed in 14 patients. The patients studied were divided into two groups, non-ischemic and ischemic, which were compared. All patients underwent ocular and systemic examination, as well as complete screening for thrombophilic risk factors.

Results:

Of the 22 patients, 15 had non-ischemic type of CRVO and 7 the ischemic type. Patients with non-ischemic CRVO showed significantly improved visual acuity (VA) at the final examination (p=0.006). Patients with ischemic CRVO showed no significant reduction in VA at the final examination (p=0.225). Systemic hypertension (27% in non-ischemic CRVO and 29% in ischemic CRVO) was the most prevalent systemic risk factor for CRVO. The mean central foveal thickness (CFT) decreased significantly from 402.3±136.2 (µm) at the initial examination to 243.8±48.1 (µm) at the final examination in the non-ischemic group (p=0.005). The mean initial CFT was 444.5±186.1 (µm) in the ischemic CRVO group, which decreased to 211.5±20.2 (µm) at the final visit (p=0.068). Pigment dispersion syndrome (PDS)/pigmentary glaucoma (PG), ocular hypertension and dehydration were equally frequent; four patients each (18%) out of 22. The clinical course of 4 younger patients with PDS/PG are described.

Conclusion:

The patients with non-ischemic CRVO showed significantly improved VA and significantly decreased CFT at the final examination. Systemic hypertension was the most prevalent risk factor for CRVO. Younger adults with CRVO also had a high prevalence of PDS/PG, ocular hypertension and dehydration. This study highlights the importance of careful IOP monitoring, and the need to investigate possible PDS/PG and to obtain an accurate history of the patient including alcohol intake and intense exercise.

Retinal vessels change in primary angle-closure glaucoma: the Handan Eye Study

Glaucoma is the second leading cause of blindness worldwide. To examine the relationship between angle closure and the retinal vessel diameter in Chinese adults, we conducted Handan Eye Study (HES), a large population-based cross-sectional study, which enrolled 6830 participants >30 year-old living in 13 randomly selected villages of Yongnian County. After adjusting for age, gender, spherical equivalent (SE), diabetes, and hypertension, the mean central retinal artery equivalent (CRAE, μm) was 127.1 ± 7.0 and 145.6 ± 4.4 in primary open-angle glaucoma (POAG) and primary angle closure glaucoma (PACG), respectively; narrower than that in normal control (156.1 ± 0.4), primary angle-closure suspect (PACS) (156.3 ± 1.1) or primary angle closure (PAC) (156.0 ± 3.4) (P = 0.001). The mean central retinal vein equivalent (CRVE, μm) was 229.0 ± 5.9 and 215.8 ± 9.5 in POAG and PACG, respectively; narrower than that in normal control (238.3 ± 0.5), PACS (241.2 ± 1.4) or PAC (242.2 ± 4.6) (P = 0.001). There was no significant difference in the mean CRAE or CRVE between PACG and POAG. Compared to the normal control (0.66), the mean arterio-venous ratio (AVR) was smaller in POAG (0.64) and PACG (0.59), whereas larger in PACS (0.65) and PAC (0.67) (P = 0.003). To conclude, PACG and POAG individuals have narrower retinal arteries and veins.

Cone pathway function in relation to asymmetric carotid artery stenosis: correlation to blood pressure

PURPOSE

To examine retinal function in relation to retinal perfusion pressure in patients with carotid artery stenosis.

METHODS

Thirteen patients with carotid artery stenosis without clinical eye disease underwent assessment of ophthalmic artery systolic blood pressure (OSP) by ocular pneumoplethysmography, carotid artery obstructive disease by ultrasonography, intraocular pressure by applanation tonometry, retinal perfusion by fluorescein angiography and retinal function by multifocal electroretinography (mfERG). Data analysis compared the eye on the most stenotic side with the fellow eye in the same patient.

RESULTS

Ophthalmic systolic pressure was 95.8 ± 13.1 mmHg on the side with the highest degree of carotid artery stenosis (mean 94.0%) and 111.7 ± 10.3 mmHg in the fellow eyes on the side with the lesser degree of stenosis (mean 33.9%). Summed mfERG implicit times (N1 and P1) were 3.4% and 2.0% longer (p = 0.013 and 0.021), and N1 and P1 amplitudes were 18.0% and 16.0% (p = 0.0041 and 0.020) lower in eyes on the side with the higher stenosis compared with the contralateral eyes. Shorter implicit times and higher amplitudes were correlated with higher brachial systolic arterial blood pressure (p = 0.0028, 0.011, 0.041 for N1, P1, N2 implicit times, respectively, and p = 0.0086, 0.016, 0.040 for N1, P1, N2 for amplitudes, respectively, corrected for OSP).

CONCLUSION

Cone function deviation was observed in clinically healthy eyes on the side with highest degree of carotid artery stenosis and was found correlated to arterial blood pressure.

Clinical and electrophysiologic outcome in patients with neovascular glaucoma treated with and without bevacizumab

PURPOSE

To investigate the clinical and electrophysiologic effect of a single intravitreal injection of bevacizumab for neovascular glaucoma (NVG) after ischemic central retinal vein occlusion (iCRVO).

METHODS

Nineteen eyes from 19 patients with NVG secondary to iCRVO were randomly allocated to either an intravitreal bevacizumab injection and panretinal photocoagulation (PRP) (10 eyes) or PRP alone (9 eyes). The primary outcome measure was the change in the total retinal function 6 months after treatment, demonstrated by full-field electroretinography (ERG). Secondary outcomes included visual acuity, intraocular pressure (IOP), glaucoma medication, additional IOP-lowering treatment, and the presence of ocular neovascularization before treatment, and 1 week, 2 months, and 6 months after treatment.

RESULTS

The regression of ocular neovascularization in the bevacizumab/PRP group was confirmed 1 week after injection. Patients in both study groups had very poor visual acuity at baseline. This remained unchanged. There was no significant difference in the mean IOP between the groups at any point in time. The a-wave amplitudes of combined rod-cone response were significantly decreased after 6 months in the bevacizumab/PRP group (p=0.028), compared with the baseline values. The a- and b-wave amplitudes of combined rod-cone response and the b-wave amplitudes of the 30-Hz flicker response were also markedly reduced compared with the PRP group (-60%, -43%, -47% vs +23%, -36%, -16%, respectively).

CONCLUSIONS

This study suggests that intravitreal injection of bevacizumab is valuable in the treatment of NVG by hastening the resolution of neovascularization, while the full-field ERG results indicate that bevacizumab may reduce the photoreceptor function in NVG patients.

Endogenous erythropoietin protects neuroretinal function in ischemic retinopathy

Because retinal ischemia is a common cause of vision loss, we sought to determine the effects of ischemia on neuroretinal function and survival in murine oxygen-induced retinopathy (OIR) and to define the role of endogenous erythropoietin (EPO) in this model. OIR is a reproducible model of ischemia-induced retinal neovascularization; it is used commonly to develop antiangiogenic strategies. We investigated the effects of ischemia in murine OIR on retinal function and neurodegeneration by electroretinography and detailed morphology. OIR was associated with significant neuroretinal dysfunction, with reduced photopic and scotopic ERG responses and reduced b-wave/a-wave ratios consistent with specific inner-retinal dysfunction. OIR resulted in significantly increased apoptosis and atrophy of the inner retina in areas of ischemia. EPO deficiency in heterozygous Epo-Tag transgenic mice was associated with more profound retinal dysfunction after OIR, indicated by a significantly greater suppression of ERG amplitudes, but had no measurable effect on the extent of retinal ischemia, preretinal neovascularization, or neuroretinal degeneration in OIR. Systemic administration of recombinant EPO protected EPO-deficient mice against this additional suppression, but EPO supplementation in wild-type animals with OIR did not rescue neuroretinal dysfunction or degeneration. Murine OIR offers a valuable model of ischemic neuroretinal dysfunction and degeneration in which to investigate adaptive tissue responses and evaluate novel therapeutic approaches. Endogenous EPO can protect neuroretinal function in ischemic retinopathy.