No-Reflow Phenomenon in Central Retinal Artery Occlusion: Incidence, Risk Factors, and Clinical Implications

A Novel Effect of Microaneurysms and Retinal Cysts on Capillary Perfusion in Diabetic Macular Edema: A Multimodal Imaging Study

Background/Objectives: The aim of this study was to investigate the potential contribution of microaneurysms (MAs) and retinal cysts to the pathogenesis of macular non-perfusion in patients with diabetic macular edema (DME) using multimodal imaging. Methods: In this cross-sectional study, 42 eyes with DME were analyzed using color fundus photography, fluorescein angiography (FA) and optical coherence tomography (OCT). Macular non-perfusion within the central 3000 µm was categorized by location and extent into foveal avascular zone enlargement (FAZE), focal non-perfusion (FNP) and diffuse non-perfusion (DNP). A custom-developed software was used to assess the colocalization of retinal cysts on OCT with areas of non-perfusion on the corresponding FA images. Also, the presence of leaky MAs adjacent to retinal cysts on FA was verified. Results: Colocalization between retinal cysts and non-perfusion was observed in 32 of 42 (76%) eyes: 19 of 23 (83%) eyes with FAZE and 13 of 16 (81%) eyes with FAZE+FNP. No cysts colocalization was found in all three eyes (100%) presenting with DNP. None of the eyes presented with FNP alone. In the remaining seven eyes (four eyes with FAZE and three eyes with FAZE+FNP), no colocalization was noticed. At least one leaky MA adjacent to retinal cysts was identified in all eyes presented with colocalization. Conclusions: Retinal cysts may contribute to the development of limited non-perfusion in DME. Leaky MAs appear to be the primary source of cyst formation, which may lead to localized capillary occlusion in the macula.

Early reperfusion in patients with acute retinal artery occlusion: A multicenter prospective study

BACKGROUND

The visual outcome after central retinal artery occlusion (CRAO) is poor, but its relationship with early reperfusion (ER) is poorly known. We evaluated the incidence of ER in acute CRAO or branch retinal artery occlusion (BRAO), and its association with clinical outcome.

METHODS

In this prospective observational multicenter study, we included patients with acute CRAO or macula-involving BRAO presenting within 24 hours from symptom onset. ER was evaluated within 24 hours after the initial clinical evaluation using indocyanine green angiography (ICGA). The primary outcome was the best-corrected visual acuity (BCVA) at 1 month.

RESULTS

In all, 70 patients were enrolled, of whom 63 (90%) had CRAO. Median age was 71 years (interquartile range: 67-77), 63% were male, median time from symptom onset to presentation was 5.3 hours (interquartile range: 3.1-15.1), and 17% received intravenous fibrinolysis. ER was identified in 34 patients (49%), of whom 21 (30%) achieved complete reperfusion (100% filling of the 55° ICGA field). Patients with ER were less likely to have hypertension and diabetes mellitus (p < 0.001 and p = 0.046, respectively). At the 1-month follow-up, BCVA was significantly better in ER patients (median BCVA 1.3 logMAR vs 1.7 logMAR, p = 0.001), with greater benefit with complete reperfusion (p for trend < 0.001). ER was also associated with improved visual field and quality of life at the 1-month follow-up (both p < 0.05).

CONCLUSION

ER occurred in almost 50% of the patients and was associated with improved visual outcomes and quality of life. Therapies that increase ER in CRAO will likely improve clinical outcomes.

CLINICAL TRIAL REGISTRATION

This study was registered on ClinicalTrials.gov (identifier NCT03049514); https://classic.clinicaltrials.gov/ct2/show/NCT03049514.

Visual outcomes of central retinal artery occlusion: Exploring treatment strategies beyond the conventional time window

BACKGROUNDS/AIMS

Central retinal artery occlusion (CRAO) is a vision-devastating emergency. However, widely-acknowledged treatment consensus is lacking and prehospital delays commonly occur. Hence, we aimed to investigate the visual outcomes of conservative treatments (CT), local intra-arterial fibrinolysis (LIF) and hyperbaric oxygen (HBO) therapy for non-arteritic CRAO (NA-CRAO) patients beyond the conventional time window.

METHODS

This retrospective comparative study included 99 NA-CRAO patients followed up for over 6 months. The subjects were divided into three groups: the CT (50 patients), LIF (10 patients) and HBO group (39 patients). The primary endpoint was the best-corrected visual acuity (BCVA) change at 6 months compared to baseline. The secondary endpoint was the improvement in BCVA at 1 year and final visits.

RESULTS

No heterogeneity regarding demographics was identified. However, the HBO group had a more extended time-to-treatment period (median 6.0 days) and more advanced-stage CRAO cases (41 % stage III) than the CT (median 4.0 days, 14 % stage III) and LIF (median 0.6 days, 20 % stage III) groups. Despite this, the HBO group exhibited a significantly greater BCVA and a higher proportion of patients achieving significant vision improvement than those in the CT group at 6-, 12-month and final exams (51.3 % vs. 24.0 %, P < 0.05). The LIF appeared to improve outcomes more than CT over time without significance.

CONCLUSION

Our study provided a concurrent comparison across 3 approaches and demonstrated that HBO therapy beyond the time window remained more effective in improving vision than CT alone for NA-CRAO patients, which had not been proposed by prior studies.

Update on central retinal artery occlusion

The medical condition referred to as "central retinal artery occlusion" (CRAO) was first documented by Albrecht von Graefe in 1859. Subsequently, CRAO has consistently been identified as a serious medical condition that leads to substantial visual impairment. Furthermore, it is correlated with vascular complications that have the potential to affect crucial organs such as the brain and heart. A considerable amount of research has been extensively published on the various aspects of this topic, which is marked by notable debates and misconceptions, especially regarding its management and outcomes. The primary aim of this review article is to analyze the latest developments in the understanding of CRAO, which includes its causes, techniques for retinal imaging, systemic evaluation, and therapeutic strategies, such as vitrectomy. This review article offers readers a comprehensive learning experience to gain knowledge on the fundamental principles and recent advancements in CRAO.

Improved visual outcomes of central retinal artery occlusion with local intra-arterial fibrinolysis beyond the conventional time window

Local intra-arterial fibrinolysis (LIF) is a promising therapeutic option for CRAO. However, the narrow time window of 6 h has greatly limited the application of LIF. In this study, we explored the efficacy of LIF beyond the conventional time windows and compared the result with conservative therapy. This prospective study included 179 CRAO patients with baseline visual acuity (VA) ≤ 20/400 treated at Renmin Hospital of Wuhan University. The mean time from vision loss to presentation was 5.5 days. 58 patients received conventional standard therapy (CST) alone.121 patients underwent LIF. Main outcome was VA improvement ≥ 0.3 logMAR. Secondary outcome was a favorable VA outcome of 20/200 or better. Logistic regressions were performed to identify predictors of visual improvement. 43% patients in the LIF group experienced VA improvement versus 19% with CST (P = 0.002). LIF was associated with 4.0-fold higher likelihood of visual improvement compared to CST (P = 0.001). Poor baseline VA (light perception or no light perception) and shortened prothrombin time (PT) were associated with greater chance of visual improvement with LIF. However, LIF showed no significant advantage over CST for favorable VA outcomes. No major complications occurred. LIF beyond the therapeutic time window improved vision in functionally blind CRAO patients and showed better efficacy when compared with CST. PT may be a potential predictor of visual outcome after LIF. Our findings could complement existing time-based treatment guidelines and potentially allow for personalized decisions on the use of LIF beyond time windows.

R-(+)-WIN55212-2 protects pericytes from ischemic damage and restores retinal microcirculatory patency after ischemia/reperfusion injury

BACKGROUND AND PURPOSE

Cannabinoids are vasoactive substances that act as key regulators of arterial tone in the blood vessels supplying peripheral tissues and the central nervous system. This study aimed to investigate the potential of R-(+)-WIN55212-2 (WIN), a cannabinoid receptor 1 agonist (CB1), as a treatment for retinal ischemia/reperfusion (I/R) injury.

EXPERIMENTAL APPROACH

Male Wistar rats were subjected to retinal I/R injury by increasing intraocular pressure in the anterior chamber. The rats were randomly divided into four groups: normal control, I/R, vehicle (pre-treated with dimethyl sulfoxide [DMSO] via intraperitoneal injection), and experimental (pre-treated with WIN at a dose of 1 ml/kg via intraperitoneal injection). The rats were sacrificed at different time points of reperfusion (1 hour, 3 hours, 6 hours, and 1 day) after inducing retinal I/R injury, and their retinas were collected for analysis. Oxygen-glucose deprived/reperfusion (OGD/R) was performed by initially perfusing the retinas with oxygenated artificial cerebrospinal fluid (ACSF), then switching to an OGD solution to simulate ischemia, followed by another perfusion with ACSF. Pericyte contraction and the "no-reflow" phenomenon were observed using infrared differential interference contrast (IR-DIC) microscopy and immunohistochemistry. Western blot, enzyme-linked immunosorbent assay (ELISA), and nitric oxide (NO) detection were used to explore the potential mechanism.

KEY RESULTS

In both the OGD/R and I/R models, retinal pericytes exhibited persistent contraction even after reperfusion. The ability of WIN to regulate the tone of retinal pericytes and capillaries was specifically blocked by the BKCa inhibitor iberiotoxin (100 nM). WIN demonstrated a protective effect against retinal I/R injury by preserving blood flow in vessels containing pericytes. Pretreatment with WIN alleviated the persistent contraction and apoptosis of retinal pericytes in I/R-induced rats, accompanied by a reduction in intracellular calcium ion (Ca2+) concentration. The expression of CB1 decreased in a time-dependent manner in the I/R group. After I/R injury, endothelium-derived nitric oxide (eNOS) levels were reduced at all time points, which was successfully reversed by WIN therapy except for the 1 day group. Additionally, the downregulation of cyclic guanosine monophosphate (cGMP) and BKCa expression at 3 hours, 6 hours, and 1 day after I/R injury was restored by pretreatment of WIN.

CONCLUSIONS & IMPLICATIONS

WIN exerted its protective effects on retinal I/R injury by inhibiting the contraction and apoptosis of pericytes through the CB1-eNOS-cGMP-BKCa signaling pathway, thus ameliorated the occlusion of retinal capillaries.

Meta-Analysis on the Efficacy of High-Dose Statin Loading Before Percutaneous Coronary Intervention in Reducing No-Reflow Phenomenon in Acute Coronary Syndrome

Currently, guidelines recommend the uptake of high-dose statins before and after percutaneous coronary intervention (PCI) in patients with acute coronary syndrome. However, the association of high-dose statins with the incidence of the no-reflow phenomenon remains unclear. This study aimed to review the evidence of preprocedural high-dose statin therapy to reduce no-reflow incidence after PCI. PubMed, Embase, and Google Scholar were searched from inception until May 2022 for studies comparing high-dose statins with low-dose or no statin therapy before PCI. Studies reporting the no-reflow phenomenon were shortlisted. The National Institutes of Health tool for randomized and cohort studies was used to assess the quality of included studies. A random-effects model was used to derive odds ratios (ORs) and their corresponding 95% confidence intervals (CIs). A total of 11 studies were included, with a population of 4,294 patients. The use of high-dose statins before PCI significantly reduced postprocedural no-reflow (OR 0.51, 95% CI 0.35 to 0.74, p = 0.0005, I² = 32%). A total of 7 studies included patients who underwent PCI without previous use of statins. A significant decrease in overall no-reflow events was observed with high-intensity statin treatment versus low-intensity statin/placebo (OR 0.55, 95% CI 0.34 to 0.88, p = 0.01, I² = 25%) among patients who were statin naive. Acute high-dose statin therapy before PCI significantly reduces the hazard of post-PCI no-reflow events in patients with acute coronary syndrome. Our results encourage the routine use of statins before PCI.

Retinal Capillary Reperfusion from Ischemic Retinal Vasculitis in Henoch-Schönlein Purpura: A Case Report

INTRODUCTION

We present a case of ischemic retinal vasculitis in adult-onset Henoch-Schönlein purpura (HSP) and the first report of capillary reperfusion through regenerative angiogenesis using optical coherence tomography angiography (OCTA).

CASE REPORT

A 34-year-old male complained of bilateral blurred vision after successive episodes of abdominal pain, purpura, and hematuria. Fundus examination showed perivascular infiltration and phlebitis. Fluorescein angiography and OCTA revealed extensive capillary nonperfusion. Laser photocoagulation was performed on the peripheral nonperfused area. Intravenous methylprednisolone with azathioprine was administered and continuously tapered. With consecutive OCTA follow-up, the capillary nonperfusion of the maculae progressively reperfused. Capillary buds and loops emerged within the nonperfused area, continued to elongate and branch, and finally connected with adjacent preexisting capillaries.

CONCLUSIONS

Regenerative angiogenesis was the mainstay process for capillary reperfusion in this patient. Systemic steroid therapy might support capillary reperfusion and recover the damaged ischemic maculae from ischemic retinal vasculitis of HSP.

Optical Coherence Tomography of Peripapillary Vessels in Giant Cell Arteritis and Ischaemic Ocular Disease

With normal retinal blood flow, cross-sectional optical coherence tomography (OCT) of retinal vessels shows a structured intravascular reflectivity profile, resembling a 'figure-of-8'. Altered profiles have been reported in vascular occlusive and haematological diseases. Giant cell arteritis (GCA) can cause visual loss, usually due to anterior ischaemic optic neuropathy (AION) or retinal artery occlusion. Our aim was to extend the assessment of OCT vascular profiles to patients with suspected GCA and to determine if any abnormalities were related to GCA per se or to ischaemic ocular conditions. This nested retrospective study included 61 eyes of 31 patients (13 with GCA). Six eyes had arteritic and seven eyes non-arteritic AION, three eyes had non-arteritic retinal artery occlusion, 11 eyes had other ocular conditions and 34 were unaffected control eyes. For each eye the appearance of structured intravascular profiles on peripapillary OCT was graded as present, partial, absent or uncertain. Non-presence of structured intravascular profiles was more frequent in AION and retinal artery occlusion than in other ocular conditions or unaffected eyes (Fisher's test, p = .0047). Based on follow-up of 25 eyes, reflectivity profiles normalised in three out of four eyes after 85 (35-245) days. Vessel profiles were not associated with GCA (p = .32) and were similar in arteritic and non-arteritic AION (p = .66). In conclusion, absence of structured intravascular reflectivity profiles may be a marker of acute ischaemia in the anterior optic nerve or inner retina. However, it did not seem specific for GCA. The prognostic value warrants further studies.

Case Report: Recanalization of Branch Retinal Artery Occlusion Due to Microthrombi Following the First Dose of SARS-CoV-2 mRNA Vaccination

Background: We report on a patient with a branch retinal artery occlusion (RAO) and its recanalization based on multimodal retinal and angiographic images after he was administered the first dose of the SARS-CoV-2 mRNA vaccine.

Case summary: A 64-year-old man complained of a right, painless, inferior field defect 3 days after the first dose of BNT162b2 vaccination. Fundus examination revealed decolorization of the right upper macula, including microthrombi in the superior proximal branch of the retinal artery. Optical coherence tomography angiography revealed upper macular hypoperfusion. Fluorescein angiography revealed prolonged arteriovenous transit to the macula. After paracentesis with antiplatelet medications, the artery was recanalized as the thrombi dissolved, and the right visual field was recovered. Re-occlusion did not occur during the 3 months after the second mRNA vaccination.

Conclusion: Non-embolic thrombotic RAO may develop shortly after the SARS-CoV-2 mRNA vaccine. Ophthalmologists should consider RAO as a possible post-vaccination adverse event. The temporal association between mRNA vaccination and RAO onset with evidence of microthrombi might provide additional clues to elucidate the unpredictive arterial thrombosis following SARS-CoV-2 mRNA vaccination.

Segmenting OCT for detecting drug efficacy in CRAO

PURPOSE

Thinning of the inner layers of the retina occurs in patients with central retinal artery occlusion (CRAO). The mechanism for such thinning may be partially due to proteolysis by a calcium-activated protease called calpain. Calpain inhibitor SNJ-1945 ameliorated the proteolysis in a past series of model experiments. The purposes of the present retrospective study were to: 1) use segmentation analysis of optical coherence tomography (OCT) images to mathematically model the loss of specific retinal layers in CRAO patients, and 2) predict the number of patients and days of observation needed for clinical trials of inhibitors against CRAO.

METHODS

A retrospective case control study was conducted by computer-aided search for CRAO (ICD10 H43.1) with at least one OCT procedure (CPT: 92134) in the OHSU Epic patient data base.

RESULTS

After initial swelling, thinning of the inner retinal layers, especially the ganglion cell (GCL) layer followed exponential decay curves. Using sample size statistics and GCL thickness as a marker in a 30-day clinical trial, 19 eyes/group could theoretically detect a 20% beneficial effect of an inhibitor against CRAO. Other markers, such as the whole retinal thickness and combined inner layers could also be used as less-specific markers.

CONCLUSIONS

Using thickness changes in the GCL layer to monitor the efficacy of potential inhibitors against CRAO is practical in human trials requiring a reasonable number of patients and relatively short trial period.

TRANSLATIONAL RELEVANCE

Measurement of GCL thickness would be a useful indicator of CRAO progression in a clinical trial of putative inhibitors.

The Utility of Fundus Fluorescein Angiography in Neuro-Ophthalmology

While its use is still widespread within the medical retina field, fundus fluorescein angiography (FFA) is increasingly falling out of favour in the investigation of neuro-ophthalmological disease, with the introduction of new technologies, particularly optical coherence tomography. FFA does, however, provide useful diagnostic and prognostic information in many neuro-ophthalmological diseases including papilloedema, pseudo-papilloedema, optic neuropathies and central retinal artery occlusion to name a few. We aim to summarise the main FFA findings in each of these conditions and highlight where FFA is of most use in providing complementary information to other modes of investigation.

Differentiating Occult Branch Retinal Artery Occlusion from Primary Open-angle Glaucoma

SIGNIFICANCE

Clinical findings in occult branch retinal artery occlusion (BRAO) can mimic those of primary open-angle glaucoma (POAG). Because management of these conditions substantially differs, accurate diagnosis is crucial. Our comparative analysis indicates that specific macular thickness variables reliably differentiate these conditions and that macular scanning may enhance routine glaucoma evaluation.

PURPOSE

The aim of this study was to identify clinical factors that reliably and efficiently identify occult BRAO masquerading as POAG.

METHODS

All subjects had comprehensive eye examinations including measurements of retinal nerve fiber layer and macular thickness (MT) using spectral-domain optical coherence tomography (SD-OCT). All subjects were asymptomatic for previous acute vision loss episodes, had optic nerve appearances suggestive of glaucoma, and exhibited SD-OCT retinal nerve fiber layer thinning with corresponding visual field loss. Macular thickness scans were divided into 64 individual thickness blocks with thin MT blocks defined by the lower 99% confidence interval from a group of normal eyes. We defined BRAO by the presence of regional inner retinal thinning with lack of inner-layer stratification on macular SD-OCT b-scan images that spatially corresponded with arteriolar distribution and visual field loss location. Primary open-angle glaucoma eyes were selected to match the BRAO eyes by age and disease severity. Pairwise and receiver operating characteristic curve analyses were used to compare occult BRAO and POAG eyes.

RESULTS

Compared with POAG (n = 52), occult BRAO eyes (n = 11) demonstrated lower cup-disc ratio, greater intereye and intraeye (superior vs. inferior) MT asymmetry, and higher frequency of thin MT blocks (<200 μm). Area under the receiver operating characteristic curve (AUC) for differentiating these conditions was highest for intraeye MT asymmetry (AUC = 0.990 [95% confidence interval, 0.925 to 1.000]) and number of thin MT blocks (AUC = 0.993 [95% confidence interval, 0.929 to 1.000]).

CONCLUSIONS

Macular thickness parameters provided accurate and efficient diagnostic capability in this study. Considering the clinical implications of inaccurate diagnosis, macular scanning may be important in baseline glaucoma evaluation.

Clinical effect of preoperative high-dose atorvastatin against no-reflow after PCI

The aim of the present study was to evaluate the use of preoperative high-dose atorvastatin to prevent the no-reflow phenomenon after percutaneous coronary intervention (PCI). A total of 138 patients with ST-segment elevation myocardial infarction, admitted from March 2014 to January 2015, were enrolled and randomly divided into 3 groups of 46 individuals each. The groups included a control group in which patients were not treated with atorvastatin before PCI; a conventional-dose atorvastatin treatment group in which patients received a single dose of 20 mg at bedtime one day prior to PCI; and a high-dose atorvastatin treatment group in which patients were treated with 40 mg divided in two doses the day before PCI. The treatment effects were assessed by re-examining the echocardiography, high-sensitivity C-reactive protein and brain natriuretic peptide (BNP) levels after the PCI. The follow-up examinations included determinations of ultrasound imaging indicators and the contact with patients was maintained for a whole year. The CTFC (frame), pro-BNP, CK-MB peak and WMSI levels of the patients in the high-dose treatment group were significantly lower than those in the conventional dose or the control group. Trombolysis in myocardial infarction ≤2 and myocardial blush grade ≤1 levels were significantly lower than those in the conventional dose group (P=0.01) or those in the control group (P=0.01), although the echocardiographic indicators of the three groups were not significantly different (P<0.05). Nevertheless, it was found that there were significantly fewer adverse cardiovascular events in the high-dose group (P<0.05 in both cases). During the follow-up period, thromboembolism and restenosis were most infrequent in the high-dose atorvastatin group. Based on our findings the oral administration of high-dose atorvastatin before bedtime, one day before the procedure, can effectively prevent no-reflow cases, reduce adverse events and improve the long-term prognosis for acute coronary syndrome patients after PCI.

Observation on therapeutic efficacy of rt-PA intravenous thrombolysis combined with compound anisodine injection on central retinal artery occlusion

The aim of the present study was to observe the clinical efficacy and safety of recombinant tissue plasminogen activator (rt-PA) combined with compound anisodine in treating central retinal artery occlusion (CRAO). Forty-eight patients diagnosed with CRAO were randomly divided into a treatment group (24 cases) and a control group (24 cases). For the control group, nitroglycerin, 654-2, methazolamide, puerarin and compound anisodine were used for the treatment, along with oxygen, massage and other conventional treatments. Besides conventional therapy, the treatment group was also given intravenous rt-PA thrombolysis. Visual acuity, fundus oculi, visual field changes were taken as indicators for efficacy evaluation. It was found that the total effective rate of the control group was 70.83%, while that for the treatment group was 91.67%, and the comparative difference between the two groups was of statistical significance (p<0.05). The visual field defect of the control group after treatment was approximately 74.26±12.91%, and the visual field defect of the treatment group after treatment approximately 35.08±16.33%; thus, the comparative difference was statistically significant (p<0.01). The comparative difference of the original contents of fibrous protein in blood in the treatment group before and after treatment was statistically significant (p<0.01). In conclusion, the result show that intravenous thrombolysis with rt-PA combined with compound anisodine is safe and effective in treating CRAO, which can significantly improve the prognosis of patients.