The Retrobulbar Spot Sign and Prominent Middle Limiting Membrane as Prognostic Markers in Non-Arteritic Retinal Artery Occlusion

Normalized Reflectivity of Middle Limiting Membrane on SD-OCT: A Measure of Acute Ischemia in CRVO

PURPOSE

To validate the quantification of the prominent middle limiting membrane (PMLM) sign, a marker of mild-to-moderate acute ischemic damage on optical coherence tomography (OCT), by measuring middle limiting membrane (MLM) reflectivity in patients with central retinal vein occlusion (CRVO) and to investigate the prognostic impact of this measure.

METHODS

Spectral Domain (SD)-OCT B-scans of 30 patients with CRVO, either sole CRVO or combined central retinal artery and vein occlusion (CCRAVO), were analyzed retrospectively and graded as PMLM present or absent. Normalized MLM reflectivity was calculated as a ratio of the maximum reflectivity within a MLM target layer and the average reflectivity of the retinal pigment epithelium (RPE).

RESULTS

Discrimination between OCT B-scans graded as PMLM present or absent based on ROC analysis was far superior with normalized MLM reflectivity (AUC >0.90) than using MLM reflectivity without normalization (AUC = 0.70). Normalized MLM reflectivity was significantly higher in study eyes than healthy fellow eyes as well as in patients with CCRAVO versus sole CRVO. Although normalized MLM reflectivity correlated significantly with baseline and outcome BCVA, we found no significant difference comparing patients with ischemic CRVO versus non-ischemic CRVO.

CONCLUSIONS

Quantifying MLM reflectivity requires normalization due to shadowing, which is usually caused by retinal haemorrhages in CRVO. RPE reflectivity proved to be a suitable reference layer. Greater normalized MLM reflectivity as a measure of mild-to-moderate acute ischemic damage indicated a worse prognosis regarding visual function in CRVO, however, it allows no risk assessment regarding the development of capillary non-perfusion or anterior segment neovascularization.

SPLIT OUTER PLEXIFORM LAYER APPEARANCE REPRESENTS AN ACQUIRED CONE DYSFUNCTION PHENOTYPE OF AUTOIMMUNE RETINOPATHY

PURPOSE

Autoimmune retinopathy (AIR) is a poorly understood condition with a wide phenotypic spectrum and heterogeneous findings on clinical examination and imaging. In this study, the authors characterize the clinical features of a recently described phenotypic subtype of AIR with a distinct split outer plexiform layer appearance on OCT.

METHODS

This was a retrospective, observational study of patients with a diagnosis of AIR seen at the University of Iowa between January 2007 and September 2023 who were found to have decreased visual acuity, central scotoma on visual field testing, split outer plexiform layer appearance on OCT, and abnormal light-adapted electroretinogram, consistent with an acquired cone dysfunction. Clinical course and multimodal imaging and physiologic testing were reviewed.

RESULTS

Ten patients were identified in the retrospective cohort. All patients presented with bilateral, asymmetric, subacute, and progressive central vision loss. A diagnosis of cancer was present or subsequently diagnosed in 5 out of 10 patients (50%). Overall, 40% of patients underwent treatment with immunosuppressives, and one patient underwent tumor resection, with partial visual recovery seen.

CONCLUSION

Patients with split outer plexiform layer appearance on OCT have an acquired cone dysfunction that is important to recognize as treatment in some cases may result in improved or stabilized visual function.

Automated Detection of Central Retinal Artery Occlusion Using OCT Imaging via Explainable Deep Learning

Objective

To demonstrate the capability of a deep learning model to detect central retinal artery occlusion (CRAO), a retinal pathology with significant clinical urgency, using OCT data.

Design

Retrospective, external validation study analyzing OCT and clinical baseline data of 2 institutions via deep learning classification analysis.

Subjects

Patients presenting to the University Medical Center Tübingen and the University Medical Center Hamburg-Eppendorf in Germany.

Methods

OCT data of patients suffering from CRAO, differential diagnosis with (sub) acute visual loss (central retinal vein occlusion, diabetic macular edema, nonarteritic ischemic optic neuropathy), and from controls were expertly graded and distinguished into 3 groups. Our methodological approach involved a nested multiclass five fold cross-validation classification scheme.

Main Outcome Measures

Area under the curve (AUC).

Results

The optimal performance of our algorithm was observed using 30 epochs, complemented by an early stopping mechanism to prevent overfitting. Our model followed a multiclass approach, distinguishing among the 3 different classes: control, CRAO, and differential diagnoses. The evaluation was conducted by the "one vs. all" area under the receiver operating characteristics curve (AUC) method. The results demonstrated AUC of 0.96 (95% confidence interval [CI], ± 0.01); 0.99 (95% CI, ± 0.00); and 0.90 (95% CI, ± 0.03) for each class, respectively.

Conclusions

Our machine learning algorithm (MLA) exhibited a high AUC, as well as sensitivity and specificity in detecting CRAO and the differential classes, respectively. These findings underscore the potential for deploying MLAs in the identification of less common etiologies within an acute emergency clinical setting.

Financial Disclosures

Proprietary or commercial disclosure may be found in the Footnotes and Disclosures at the end of this article.

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.

Presence of Embolic Source and Outcome in Central Retinal Artery Occlusion

OBJECTIVES

The etiology of central retinal artery occlusion (CRAO) is unclear in approximately 50% of patients, suggesting pathomechanical heterogeneity; moreover, little is known about outcomes according to etiology. This study investigated whether the presence of an embolic source affects outcome in CRAO.

METHODS

CRAO patients within 7 days of symptom onset were retrospectively enrolled. Clinical parameters, including initial and 1-month visual acuity, CRAO subtype, and brain images, were reviewed. CRAO etiology was categorized as CRAO with or without an embolic source (CRAO-E+ and CRAO-E-). Visual improvement was defined as a decrease in logarithm of the minimum angle of resolution ≥0.3 at 1 month.

RESULTS

A total of 114 patients with CRAO were included. Visual improvement was noted in 40.4% of patients. Embolic sources were identified in 55.3% of patients, and visual improvement group rather than no improvement group was more commonly associated with the presence of an embolic source. In multivariable logistic regression analysis, CRAO-E+ independently predicted visual improvement (odds ratio 3.00, 95% CI 1.15-7.81, p = 0.025).

DISCUSSION

CRAO-E+ was found to be associated with a better outcome. CRAO-E+ may be more prone to recanalization than that CRAO-E-.

Retinal OCT findings in acute central retinal artery occlusion of varying severity at different disease stages - a retrospective, observational study

PURPOSE

To study the optical coherence tomography (OCT) changes in eyes with acute central retinal artery occlusion (CRAO) of different severity and at different disease stages.

METHODS

The study included acute CRAO cases of < 7 days duration, imaged on OCT at various time points. Based on the OCT findings at presentation, cases were classified into three severity groups: mild, moderate, and severe. OCT scans were evaluated and classified into four-time intervals based on symptom duration.

RESULTS

There were 39 eyes from 38 patients with acute CRAO who underwent 96 OCT scans. At presentation, the study had 11, 16, and 12 cases of mild, moderate, and severe CRAO, respectively. Middle retinal layer opacification was more common in mild CRAO cases, which caused inner retinal layer thinning over time. Moderate CRAO cases had total inner retinal layer opacification, which resulted in retinal thinning over time. Prominent middle limiting membrane (p-MLM) sign was seen in mild and moderate CRAO eyes while were not visualised in severe CRAO. This sign gradually faded out over time. Other OCT findings in higher grades of CRAO included inner retinal fluid, neurosensory detachment, internal limiting membrane detachment, hyperreflective foci, and posterior vitreous opacities. Regardless of the CRAO grade, the final end-point seen was inner retinal layer thinning over time.

CONCLUSION

OCT in CRAO is a useful for determining the severity of retinal ischemia, disease stage, tissue damage mechanism, and final visual outcome. More prospective studies analysing a larger number of cases at fixed time points will be required in the future.

TRIAL REGISTRATION

Trial Registration Number: Not applicable.

[Cardiovascular risk factors, haemostasis and antithrombotic treatment in retinal vessel occlusion]

Venous and arterial retinal vascular occlusions are age-related disorders, generally associated with classical cardiovascular risk factors, rather than an isolated ocular disease. As affected patients often also have an increased general risk for other vascular diseases, such as ischemic stroke, an interdisciplinary clarification of cardiovascular risk factors and systemic comorbidities is essential for all patients. Extended hemostaseological investigations may be recommended in those patients who do not match the typical risk profile. Patients at a young age by the time of manifestation, without conventional risk factors as well as patients with an increased risk of developing antiphospholipid syndrome may require a selective clinical investigation including testing for thrombophilic risk factors. Recent studies have clearly demonstrated an association between coagulation and lipid metabolism disorders and the development of both retinal vein and artery occlusions in specific subgroups of patients. Therapeutic approaches to treat retinal vascular occlusions or reduce the long-term risk of recurrences with anticoagulant or antiplatelet drugs have not gained widespread acceptance. However, intravenous thrombolysis may be a valuable treatment option for central retinal artery occlusions within a short time to treatment therapeutic window. For defined disorders of the coagulation system, the administration of antithrombotic drugs to reduce the general vascular risk can be a reasonable approach. This article provides an overview of cardiovascular risk factors, the general vascular risk and the current state of knowledge on ophthalmologically relevant disorders of coagulation and lipid metabolism in patients with venous and arterial retinal vascular occlusions.

Inner Retinal Layer Hyperreflectivity Is an Early Biomarker for Acute Central Retinal Artery Occlusion

Purpose

To investigate inner retinal hyperreflectivity on optical coherence tomography (OCT) as a potential biomarker indicating acute central retinal artery occlusion (CRAO).

Methods

A total of 56 patients at two university hospitals with acute CRAO (symptom onset ≤48 h) were included in this retrospective study. The optical intensity of the inner retinal layers was determined in both eyes and the relationship between symptom onset and inner retinal layer optical intensity in OCT scans compared to the unaffected fellow eye was analyzed. Several differential diagnoses [central retinal vein occlusion, anterior ischemic optic neuropathy, diabetic macular edema, and subretinal fibrosis/disciform scar (Junius-Kuhnt)] served as controls to validate optical intensity-based diagnosis of CRAO.

Results

CRAO strongly correlated with an increased inner retinal layer hyperreflectivity in this cohort with acute CRAO with a time since symptom onset ranging from 1.1 to 48.0 h. Receiver operating characteristic (ROC) analysis showed an area under the curve of 0.99 to confirm CRAO with a true positive rate of 0.93 and a false positive rate of 0.02. No correlation between optical intensity and time since symptom onset was noticeable. None of the differential diagnoses did show an elevated optical intensity of the inner retinal layers as it was detectable in CRAO.

Conclusion

OCT-based determination of inner retinal layer hyperreflectivity is a very promising biomarker for a prompt diagnosis of CRAO in an emergency setting. This may be of major interest to speed up the administration of a possible thrombolytic treatment.

[Update on intravenous lysis treatment : The REVISION trial]

BACKGROUND

To date, no evidence-based treatment for acute non-arteritic central retinal artery occlusion (CRAO) exists. Considering the limited ischemia tolerance of the retina and the results of multiple case series, increasing expectations are directed towards an early intravenous thrombolysis within 4.5 h after CRAO onset.

OBJECTIVE

The current literature regards timely retinal reperfusion as the only potentially beneficial therapeutic option to treat non-arteritic CRAO. Available data on the efficacy and safety of thrombolysis in CRAO are presented and discussed. On the basis of these data, the prospective, randomized, double-blind, placebo-controlled REVISION trial (early REperfusion therapy with intravenous alteplase for recovery of VISION in acute central retinal artery occlusion) will shortly be initiated in 25 centers across Germany in order to investigate early intravenous thrombolysis in acute CRAO. The main inclusion criteria of the REVISION trial are outlined, which may help ophthalmologists to identify study candidates and facilitate rapid referral to a study center.

CONCLUSION

The efficacy of intravenous thrombolysis in acute ischemic stroke is critically time dependent. This may also be assumed in acute CRAO; however, definite evidence still needs to be provided. Until then, the motto "time is retina" should be applied and intravenous thrombolysis should be offered to CRAO patients as part of randomized trials (such as REVISION). According to the current literature, other acute treatment approaches (such as paracentesis) are not indicated.

[Nonaretritic central retinal artery occlusion as marker for the generalized vascular risk]

BACKGROUND

Retinal artery occlusion (RAO) represents a limiting visual perception for affected patients. In all efforts to improve function it must not be forgotten that in the vast majority of cases the cause is one or more severe vascular or cardiac diseases, which can cause RAO just as ischemic stroke and can also be life-threatening.

OBJECTIVE

The aim of this article is to present the available literature and to explain the importance of an intensive neurological internal medical clarification in RAO patients.

CONCLUSION

Although cardiovascular diseases are already known in most patients at the onset of an RAO, further risk factors are detected in almost 80% of cases. Therefore, and because of the high risk for recurrent thromboembolism, immediate and standardized neurological internal medical clarification of the cause is urgently recommended after an acute RAO in the context of an inpatient stay.