Comparing Macular Thickness Measurements in Patients with Diabetic Macular Edema with the Optos Spectral OCT/SLO and Heidelberg Spectralis HRA + OCT

The aim of this study was to compare measurements of macular thickness, obtained from patients with diabetic macular edema, using two spectral-domain optical coherence tomography (SD-OCT) devices. These were the Spectralis Heidelberg Retina Angiograph + Optical Coherence Tomography (HRA + OCT) (Heidelberg Engineering), which is often considered the gold-standard for OCT measurement, and the Spectral Optical Coherence Tomography/Scanning Laser Ophthalmoscopy (OCT/SLO) (Optos plc), which can additionally perform microperimetry, a useful measure of visual function. In this prospective observational study, each eye had SD-OCT performed with both devices on the same day by the same investigator. Mean retinal thickness was calculated, and compared between the devices, for central and parafoveal zones within 3 mm of the fovea. 62 eyes were included. In the central, superior, temporal, inferior and nasal zones respectively, mean retinal thickness with Spectralis HRA+OCT was (in microns) 310, 343, 344, 332 and 340; measurements with Spectral OCT/SLO were 237, 298, 297, 289 and 290. Pearson correlations between the devices were 0.752, 0.85, 0.928, 0.839, and 0.823 (p < 0.0001). Although absolute measurements between the devices were significantly different and therefore not interchangeable, the correlation between the devices was over 75% and statistically significant in all zones. Thus, the Spectral OCT/SLO could reliably be used for SD-OCT in patients who may also require microperimetry assessment.