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A. C. Walsh, S. R. Sadda; Comparison of Clinical Findings From High Resolution Fourier Domain and Conventional Time Domain OCT. Invest. Ophthalmol. Vis. Sci. 2007;48(13):2604.
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© ARVO (1962-2015); The Authors (2016-present)
Three dimensional, high resolution Fourier domain OCT (3D-OCT) is a new clinical alternative to conventional time domain OCT (TD-OCT). The higher resolution and dense grid mapping of the retina by 3D-OCT has been purported to enhance the identification of clinically-relevant findings which may be missed by the sparse radial line data of TD-OCT. To study this hypothesis, we compared the sensitivities of TD and 3D-OCT for the detection of several clinical findings commonly diagnosed on OCT.
3D-OCT scans (128 B-scans x 512 A-scans) were obtained using a prototype 3D Fourier domain OCT instrument (Topcon, Japan) in 50 eyes of 28 consecutive patients undergoing traditional high resolution (6 B-scans x 512 A-scans) StratusOCT (Carl Zeiss Meditec, USA). Two graders reviewed each set of scans independently in a masked fashion and completed a standard form for each case recording the presence or absence of various findings (Column 1 of Table). ‘Questionable’ and ‘Can’t grade’ levels were also allowed for each finding. Discrepancies between graders were adjudicated. The ground truth for each case was determined by merging the findings from both methods to generate the maximal possible level of detection for each finding.
The sensitivity of detection for each clinical finding is shown in the Table for both instruments. The average sensitivity for detection of all features in this study was 97% for 3D-OCT and 83% for TD-OCT. If questionable grades were excluded, the overall sensitivity for 3D-OCT increased to 99% and for TD-OCT to 89%. Clinical findings were identical between devices in 18% (9/50) of cases. 3D-OCT detected features that were not visible on conventional OCT scans in 78% (39/50) of cases. In 6 cases (12%), time domain OCT detected findings that were not evident on 3D-OCT. The average subjective rating of image quality was 15% higher for 3D-OCT than TD-OCT.
3D-OCT has better image quality and a higher sensitivity than TD-OCT for detection of many clinically-relevant features in macular diseases.
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