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Jennifer Yen Luu, Patricia Sha, Mary K Durbin; Comparison of Spectral-Domain and Swept-Source Optical Coherence Tomography Choroidal Thickness Measurements in Normal Eyes. Invest. Ophthalmol. Vis. Sci. 2016;57(12):2178.
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© ARVO (1962-2015); The Authors (2016-present)
To compare choroidal thickness measurements in normal eyes scanned with Zeiss spectral-domain optical coherence tomography (SD-OCT) and swept-source optical coherence tomography (SS-OCT).
High-definition one line raster scans (1024 A-scans, 100 B-scans averaged) were acquired on both a CIRRUS SD-OCT (ZEISS, Dublin, CA) and a Zeiss SS-OCT prototype in 21 eyes of 13 subjects, with no retinal or choroidal pathology. The SD-OCT has a broadband superluminescent diode light source centered at 840nm, while the SS-OCT utilizes a swept laser source centered at 1050nm. For each eye, a HD 1 Line 100x scan with EDI (9mm line) for SD-OCT and a HD Spotlight scan (12mm line) for SS-OCT were acquired. Choroidal thickness (CT) was manually measured as the perpendicular distance from the posterior edge of the retinal pigment epithelium to the choroidal-scleral border by two independent graders. Three choroidal thickness measurements were made for each eye: subfoveal (SFCT), 3000µm nasal to the fovea (NCT), and 3000µm temporal to the fovea (TCT).
The choroidal-scleral border was identifiable in 62% of eyes with SD-OCT compared to 100% of eyes with SS-OCT (p<0.05; Fisher exact test, 2-tailed). In eyes measured by both devices, the mean SFCT was 236±11.9µm with SD-OCT vs 235±11.9µm with SS-OCT. Mean NCT was 116±10.8µm with SD-OCT vs 115±9.2µm with SS-OCT. Mean TCT was 203±13.3µm with SD-OCT vs 190±12.2µm with SS-OCT. For the mean SFCT, NCT, and TCT, there was no statistically significant difference between SD-OCT and SS-OCT (p=0.57 SFCT, p=0.87 NCT, p=0.19 TCT; paired t-test, 2-tailed). Intergrader correlation was strong for SFCT (r=0.98 SD-OCT, r=0.97 SS-OCT; Pearson’s test), decreasing peripheral to the fovea. Similarly, SFCT interdevice correlation was strong (r=0.98, Pearson’s test), decreasing peripheral to the fovea. Bland-Altman plots showed an increase in measurement variability with thicker choroids for both devices.
While there was no significant difference between SD-OCT and SS-OCT choroidal thickness measurements, there was a significant difference in the ability to identify the choroidal-scleral border. SS-OCT allowed choroidal thickness to be reproducibly measured in 100% of normal eyes. These findings suggest that SS-OCT may be more effective for measuring choroidal thickness.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.
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