Evaluation of Time Domain and Spectral Domain Optical Coherence Tomography in the Measurement of Diabetic Macular Edema

¹ Division of Epidemiology and Clinical Research, National Eye Institute/NIH, Bethesda, Maryland, United States; NIH, Division of Biometry & Epidemiology, National Eye Institute/NIH, 9000 Rockville Pike, Bethesda, Maryland, 20892, United States
² Division of Epidemiology and Clinical Research, National Eye Institute/NIH, Bethesda, Maryland, United States
³ Division of Biometry & Epidemiology, National Eye Institute / NIH, Bethesda, Maryland, United States; Division of Epidemiology and Clinical Research, National Eye Institute/NIH, Bethesda, Maryland, United States
⁴ Office of Scientific Director, National Eye Institute/NIH, 7 Memorial Drive, Bethesda, Maryland, 20892, United States

^* To whom correspondence should be addressed. E-mail: wongw{at}nei.nih.gov.

	Abstract

Purpose: To evaluate macular thickness and volume measurements and their intrasession repeatability in two optical coherence tomography (OCT) systems, the Stratus OCT, a time domain system, and the Cirrus HD-OCT, a spectral domain system, in the context of diabetic macular edema (DME). Methods: Thirty-three eyes from 33 diabetic patients with clinically significant macular edema (CSME) were scanned in a single session, by a single operator, on both OCT systems. Macular thickness measurements of nine standard macular subfields and total macular volume were obtained and analyzed. Bland-Altman plots were constructed to assess agreement in macular measurements. Intraclass correlation coefficients (ICCs), coefficients of repeatability (CRW), and coefficients of variation (CVW) were used to assess intrasession repeatability. Results: Macular thickness in 9 retinal subfields and macular volume were significantly higher in Cirrus HD-OCT system compared to the Stratus OCT system. Subfield thickness and total volume measurements, respectively, were 30-55 µm and 3.2 mm³ greater for the Cirrus HD-OCT system compared to the Stratus OCT system. Both Stratus OCT and Cirrus HD-OCT systems demonstrated high intrasession repeatability, with overlapping ranges for CRW, CVW, and ICC. Repeatability measures (CRW and CVW) differed significantly between systems in only one out of 9 subfields (outer temporal subfield). Conclusions: Absolute measures of macular thicknesses and volume in patients with DME differed significantly in magnitude between Stratus OCT and Cirrus HD-OCT systems. However, both OCT systems demonstrated high intrasessional repeatability measures. While the two systems may not be used interchangeably, they appear equally reliable in generating macular measurements for clinical practice and research.

Key Words: diabetic retinopathy, tomography, macular edema

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