[Internistic clarification of retinal vascular occlusions]

Retinal vascular occlusions require close cooperation of different medical disciplines to ensure optimal care of the affected patients. The medical clarification between arterial and venous occlusions is comparable but in the case of retinal arterial occlusions it should be carried out immediately. The most important associated diagnoses are arterial hypertension, diabetes mellitus, dyslipidemia, and atrial fibrillation. In younger patients and in the absence of risk factors, a search for rarer causes should be carried out giant cell arteritis in particular should be excluded. In both types of occlusions a causative glaucoma must also be considered.

High prevalence of thrombophilic risk factors in patients with central retinal artery occlusion

INTRODUCTION

Central retinal artery occlusion (CRAO) is a common cause of blindness and visual morbidity. In the majority of cases, it is related to thrombotic embolism. Nevertheless, the role of inherited or acquired thrombophilic risk factors in CRAO pathogenesis has not been comprehensively studied.

METHODS

In 126 CRAO patients (66 [52.4%] men, median age 55 [range: 18-80] years) and 107 matched controls (56 [52.3%] men, median age 53 [range: 34-78] years) we evaluated classical atherosclerotic risk factors, including serum lipid profile and glucose level, analyzed intima-media complex thickness (IMT) of external carotid arteries, and performed transthoracic echocardiography. Furthermore, we established the prevalence of inherited and acquired thrombophilic risk factors, such as factor V Leiden (FVL) and prothrombin 20210 G/A genetic variants, plasma activity of factor (F) VIII, protein C and antithrombin activity, and free protein S levels. We also assessed the presence of antiphospholipid antibodies (APLA) and evaluated blood homocysteine in all enrolled subjects. Additionally, we estimated the occurrence of Val34Leu polymorphism of the A subunit of coagulation factor XIII (FXIII-A) in both groups as a potential thrombosis-protecting factor.

RESULTS

Among traditional atherosclerotic risk components, obesity/overweight and hypercholesterolemia were the most common in the CRAO group and occurred in 103 (81.7%) and 85 (67.5%) patients, respectively. CRAO patients also had elevated IMT and altered echocardiographic parameters, indicating diastolic cardiac dysfunction. In thrombophilia investigations, at least one laboratory risk factor occurred in 72.2% (n = 91) of CRAO patients, with APLA as the most frequent, detected in 38.1% (n = 48) of them (almost seven times more frequent than in controls, p < 0.001). Deficiencies in protein C activity and free protein S levels were also common in the CRAO group, reported in 17.5% (n = 22) and 19.8% (n = 25) of patients, respectively. Interestingly, among two analyzed prothrombotic genetic variants, only the FVL was related to CRAO, with the allelic frequency 2.4 times more prevalent than in controls (p = 0.044). Finally, the CRAO group was characterized by hyperhomocysteinemia, almost twice as common as in controls (p = 0.026). Antithrombin deficiency, elevated FVIII, and FXIII-A Val34Leu polymorphism were not associated with CRAO.

CONCLUSIONS

Our findings suggest that thrombophilia plays a vital role in the pathogenesis of CRAO. Thus, proper laboratory screening should be considered in the primary and secondary prevention of those episodes, with implementing appropriate therapy as needed.

Standard Diffusion-weighted MRI for the Diagnosis of Central Retinal Artery Occlusion

Purpose

To evaluate diffusion abnormalities of the retina and optic nerve in patients with central retinal artery occlusion (CRAO) using standard stroke diffusion-weighted magnetic resonance imaging (DWI).

Methods

In this case-control study, DWI scans of patients with nonarteritic CRAO were retrospectively assessed for acute ischemia of the retina and optic nerve. Two neuroradiologists, blinded for patient diagnosis, randomly evaluated DWI of CRAO patients and controls (a collective of stroke and transient ischemic attack [TIA] patients) for restrictions of the retina and optic nerve. We calculated statistical quality criteria and analyzed inter-rater reliability using unweighted Kappa statistics.

Results

20 CRAO patients (60,6 ± 17 years) and 20 controls (60,7 ± 17 years) were included in the study. Sensitivity, specificity, positive and negative predictive values for retinal DWI restrictions were 75%/80%/79%/76% (reader 1) and 75%/100%/100%/80% (reader 2), respectively. Unweighted Kappa was κ = 0,70 (95% CI 0,48‑0,92), indicating “substantial” interrater reliability. In comparison, sensitivity, specificity, PPV and NPV (positive and negative predictive values) for restrictions of the optic nerve in CRAO were 55%/70%/65%/61% (reader 1) and 25%/100%/100%/57% (reader 2). Inter-rater reliability was “fair” with unweighted Kappa κ = 0,32 (95% CI 0,09‑0,56).

Conclusions

Retinal diffusion restrictions were present in a majority of CRAO patients and detectable with reasonable sensitivity, high specificity and substantial inter-rater reliability. Further studies are necessary to study time dependency of retinal diffusion restrictions, improve image quality and investigate the reliability of retinal DWI to discern CRAO from other causes of acute loss of vision.

Electronic supplementary material

The online version of this article (10.1007/s00062-020-00955-6) contains supplementary material, which is available to authorized users.

Central Retinal Artery Occlusion Secondary to Patent Foramen Ovale: The Unexpected Journey of a Paradoxical Embolus

Central retinal artery occlusion (CRAO) represents one of the most devastating ophthalmic emergencies, since the inner two-thirds of the retina lose their blood supply. The acute obstruction of the central retinal artery is characterized by severe, sudden and unilateral painless visual loss and usually occurs secondary to an embolus of cardiovascular origin. A paradoxical thromboembolic event of the central retinal artery through patent foramen ovale is an exceptionally unusual clinical entity as well as a great diagnostic challenge since the source of initial thrombus formation requires extensive investigation. Herein, we aim to describe a patient with no significant comorbidities who experienced a paradoxical thromboembolic episode of central retinal artery associated with patent foramen ovale.

[Retinal artery occlusion]

Retinal artery occlusion leads to profound visual impairment in the affected eye. It is rarely caused by local ophthalmic pathologies. Most patients present with a large number of cardio- and cerebrovascular risk factors. Visual loss is the leading symptom in central retinal artery occlusion (CRAO), whereas a circumscribed visual field defect is claimed in branch retinal artery occlusion (BRAO). Although many attempts have been made to improve the course of the disease, no effective therapy is available. There is some hope that intravenous fibrinolysis could influence the natural course but the therapeutic window is small (ca. 4.5 h), and treatment efficacy is still not proven. It is important for ophthalmologists to guide the patients to a comprehensive and prompt neurological and cardiological diagnostic work-up.