Capturing the Occult Central Retinal Artery Occlusion Using Optical Coherence Tomography

Abstract

Aims: To report spectral domain optical coherence tomography (OCT) findings in cases of impending or occult central retinal artery occlusion (CRAO) in which a diagnosis other than CRAO was made on initial presentation. Methods: Retrospective, observational case series of patients diagnosed with CRAO for whom on initial presentation fundal examination and OCT findings were deemed unremarkable and/or a diagnosis other than CRAO was made. OCT images from the initial presentation were then reviewed for evidence of inner retinal ischaemia.Results: 214 cases of CRAO were identified. 11 patients (5.14%) had been given an alternative initial diagnosis at their first presentation in casualty and were included. The age range was 20-84 years and 81% (9/11) were male. On review of initial OCT imaging performed in casualty, all cases had evidence of inner retinal ischaemia.Conclusions: CRAO is an ophthalmic emergency which leads to vision loss which is often irreversible. Examination of the fundus may be normal early in the course of the disease and therefore a timely diagnosis may be missed. This case series reports the OCT findings of inner retinal ischaemia in patients with occult or impending CRAO which may aid in the early diagnosis and referral to stroke services.

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

“…Typically, CRAO is a clinical diagnosis, though funduscopic changes, such as a cherry red spot or retinal pallor, may be lacking within the IVT-relevant very early phase, while ischemic signs may already become apparent on optical coherence tomography (OCT) scans ( 8 ). OCT provides high resolution non-invasive microstructural retinal images and has been shown to be a valuable diagnostic instrument for CRAO ( 9 – 16 ).…”

“…Whereas the hyperreflectivity of the inner retinal layers is discussed to be most likely due to an increased intracellular ischemic edema, whereas consequently hyporeflectivity of the outer layers is caused by the decreased signal permeability of the edematous inner retinal layers ( 19 , 20 ). However, as the retinal thickness often is normal or only mildly increased within the first hours ( 8 , 10 , 16 ), we hypothesized that the ischemia-induced increase in optical intensity may potentially be visible as the first ischemic sign anteceding retinal edema. This study therefore investigated the optical intensity of the inner retinal layers as a diagnostic criterium of CRAO and as a discriminator between potential differential diagnoses of CRAO with (sub-)acute vision loss.…”