Comparison of time domain Stratus OCT and spectral domain SLO/OCT for assessment of macular thickness and volume

Abstract

Purpose: To compare retinal thickness and volume measurements obtained with Stratus time domain optical coherence tomography (OCT) and spectral domain scanning laser ophthalmoscope OCT (SD-SLO/OCT).

Methods: In a cross-sectional study, 52 eyes with a normal macula, 30 eyes with retinal oedema, and 10 eyes with a myopia higher than 6 D have been evaluated with both time domain OCT (TD-OCT, Stratus OCT, Carl Zeiss Meditec, USA) and SD-SLO/OCT (OTI, Toronto, Canada). Retinal thickness and volume measurements in the nine areas of the 6-mm ETDRS ring were compared. Artefacts were defined as the discordance between the automatically detected anterior and posterior retinal boundaries and the boundaries detected by the examiner.

Results: Artefacts were more frequent with TD-OCT (35 vs26%). Mean retinal thickness was significantly higher with SD-SLO/OCT by 30.1 microm (+/-25.8) (P=0.003) in presence of the artefacts and by 39.2 microm (+/-25.8) (P=0.003) after their exclusion. The correlation between the two retinal thickness data sets before exclusion of the artefacts (r=0.59, P<0.001) increased after their removal (r=0.84, P<0.001). A strong correlation was present between the two retinal volume data sets before (r=0.94, P<0.001) and after exclusion of the artefacts (r=0.96, P<0.001).

Conclusions: SD-SLO/OCT produced fewer artefacts than Stratus TD-OCT. This could be attributed to the greater resolution and acquisition speed of SD-SLO/OCT. The macular retinal thickness values measured with SD-SLO/OCT were significantly higher than those measured with Stratus TD-OCT. Retinal volumes measured with Stratus TD-OCT and SD-SLO/OCT were strongly correlated.