Determination of Ischemia Onset Based on Automatically Generated Spectralis SD-OCT Values in Acute Central Retinal Artery Occlusion

Abstract

Acute central retinal artery occlusion (CRAO) induces a time-dependent increase in retinal thickness. By manually measuring the relative retinal thickness increase (RRTI) in comparison to the contralateral eye based on optical coherence tomography (OCT), ischemia onset within the past 4.5 hours could be determined with 100% sensitivity and 94.3% specificity. To enable examiner-independent and quicker diagnostics, we analyzed the RRTI using the automatic retinal thickness measurement. In this retrospective study, 28 eyes were evaluated with an acute CRAO (<46 hours). All patients received a Spectralis SD-OCT image of both eyes. The RRTI was calculated for the ETDRS sectors using the Segmentation Module for Single Retinal Layer Analysis. Receiver operating characteristic (ROC) analysis was performed to determine patients ≤4.5 hours by RRTI. In all sectors, time to OCT (TTO) and RRTI correlated positively. The optimal cutoff point to detect CRAOs ≤4.5 hours was between 18.7% nasally and 22.9% RRTI temporally. Sensitivity and specificity varied between the sectors with 90–95% sensitivity and 89–100% specificity. In conclusion, the automatic measurement of RRTI also allows the differentiation of CRAOs within a possible therapeutic time window ≤4.5 hours and CRAOs ≥4.5 hours with a high sensitivity and specificity. Additionally, it offers quicker, easier, and a user-independent assessment of ischemia onset, helping to set a base for establishing automatic indices generated by the OCT machines.

Central retinal artery occlusion – detection score

“…After the REVISION-Trial, data on the robustness of the questionnaire will be available. Furthermore, as the REVISION-Trial will be investigating the biomarkers observed in ocular coherence tomography (14,17), it should be possible to diagnose CRAO without fundoscopy in the future. Diagnosing CRAO without fundoscopy would be especially important in stroke units, which frequently lack the ophthalmologist expertise to confirm CRAO, keeping in mind that the effectivity of IVT seems to be extremely time-dependent (9,10).…”

“…Over half of the stroke units in Germany (51.9%) reported a lack of ophthalmologic expertise (13). Furthermore, fundoscopic anomalies, such as a cherry red spot or visible retinal pallor, may be lacking within the first hours after symptom onset (9), which is why alternative diagnosing tools and biomarkers for retinal ischemia are being investigated (14)(15)(16)(17)(18)(19). All diagnosing tools not involving fundoscopy may enhance the chances of CRAO patients being treated within 4.5 h after symptom onset.…”

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

“…Administration of IVT within 4.5 h shows a superior visual prognosis compared to the untreated natural course ( 4 , 6 , 7 ). The RRTI, the change of retinal thickness in the affected compared to the healthy fellow eye, is a parameter showing temporal changes and therefore allowing a highly accurate estimate of ischemia duration, which can be essential when the exact onset of symptoms cannot be reported reliably ( 10 , 16 , 17 ). Furthermore, the RRTI might reveal the amount ischemia induced retinal damage (higher RRTI represents more severe damage).…”

“…Several retinal ischemia biomarkers can be visualized early, using OCT imaging within the acute phase of CRAO. Besides a loss of structure of the retinal layers, ischemic intracellular edema causes a time-dependent increase in retinal thickness, which eventually resolves and is followed by severe inner retinal atrophy in the chronic phase ( 9 , 10 , 12 , 14 – 18 ). The relative retinal thickness increase (RRTI, retinal thickness increase at the thickest portion of the papillomacular bundle of the affected compared to unaffected eye) may provide information about the onset of ischemia with high accuracy ( 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.…”