Automated measurement of central macular fluid volume is a more accurate diagnostic biomarker for diabetic macular edema (DME) than central subfield thickness, according to a study published in JAMA Ophthalmology. 

Investigators conducted a cross-sectional observational study to assess the accuracy of automated central macular fluid volume (CMFV) measurement via optical coherence tomography (OCT) and OCT angiography (OCT-A) for diagnosing DME. The study enrolled 215 eyes of  215 patients with diabetes (117 women [54.4%]; mean age 59.6±12.4 years. All participants underwent comprehensive examinations, 6 × 6 mm macular structural OCT horizontal raster scans, and 6 × 6 mm macular OCT-A volumetric scans.

Between January 1 and March 30, 2020, 2 retinal specialists reviewed the structural scans independently and diagnosed DME if intraretinal or subretinal fluid were present. DME was deemed center-involved if fluid was present within the central fovea (central 1 mm circle). A third retinal specialist arbitrated any discrepancies. The mean central subfield thickness (CST) within the central fovea was measured on structural OCT horizontal raster scans. A deep-learning algorithm automatically quantified fluid volumes on 6 × 6-mm OCT angiography volumetric scans and within the central foveas.


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DME was present in 136 eyes, and 93 of the cases were center-involved. The area under the receiver operating characteristic curve (AUROC)  of CMFV for the diagnosis of center-involved DME was 0.907, larger than that for CST (0.832), according to the findings. When the specificity was set at 95%, the sensitivity of CMFV was higher than that of CST (79% vs 54%).

More specifically, the AUROC of CMFV for diagnosis of center-involved DME (0.907 [95%CI, 0.861-0.954]) was greater than the AUROC of CST (0.832 [95%CI, 0.775-0.889]; P = .02). With the specificity set at 95%, the sensitivity of CMFV for detection of center-involved DME (78.5% [95%CI, 68.8%-86.3%]) was higher than that of CST (53.8% [95%CI, 43.1%-64.2%]; P =.002). Center-involved DME cases not detected by CST but detected by CMFV were associated with a thinner CST (290.8 μm [95%CI, 282.3-299.3 μm] vs 369.4 μm [95%CI, 347.1-391.7 μm]; P < .001), higher proportion of previous macular laser treatment (11 of 28 [39.3%; 95%CI, 21.5%-59.4%] vs 12 of 65 [18.5%; 95%CI, 9.9%-30.0%]; P =.03), and female sex (20 of 28 [71.4%; 95%CI, 51.3%-86.8%] vs 31 of 65 [47.7%; 95%CI, 35.1%-60.5%]; P =.04).

Limitations of the study include its cross-sectional design. In eyes with a low signal strength index and mild DME with mainly parafoveal fluid, DME may be missed by measuring CMFV. Further, the study’s use of 2 different OCT instruments and scan patterns may lead to some discrepancies. Additionally, because the deep learning–based algorithm used in the study requires dense OCT-A volumetric scans, generalizability may be limited. The inclusion of only patients with type 1 diabetes of longer than 5-year duration or type 2 diabetes of any duration and age between 18 and 85 years and exclusion of pregnant or lactating women also may limit the generalizability. Lastly, the study doesn’t determine if CMFV is associated with better clinical care.

Disclosure: Some study authors declared affiliations with the biotech, pharmaceutical, and/or device companies. Please see the original reference for a full list of authors’ disclosures.  

Reference

You QS, Tsuboi K, Guo Y, et al. Comparison of central macular fluid volume with central subfield thickness in patients with diabetic macular edema using optical coherence tomography angiography. JAMA Ophthalmol. Published online May 13, 2021. doi:10.1001/jamaophthalmol.2021.1275.