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D. I. Koufakis, P. J. Patel, F. K. Chen, A. Tufail, L. Da Cruz; Detecting Spectral-Domain Optical Coherence Tomography Features of Choroidal Neovascularization Activity Using Raster Line and Radial Line Scan Protocols. Invest. Ophthalmol. Vis. Sci. 2008;49(13):920.
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© ARVO (1962-2015); The Authors (2016-present)
Optical coherence tomography (OCT) has assumed a central role in determining retreatment with intravitreal anti-VEGF agents in the treatment of neovascular age-related macular degeneration (nAMD). Conventional imaging protocols use 6 radial line scans with each line angled at 30o to each other with large gaps between scan lines. The recent introduction of spectral-domain (3D) OCT allows imaging of more retinal points using a raster line scan protocol with the potential to detect pathology missed by radial line scan protocols. However, no studies have investigated the potential advantage of raster line scanning in detecting disease activity in nAMD.
This is a retrospective analysis of 3D-OCT images (SOCT Copernicus®, Optopol, Poland) from 30 consecutive patients attending for treatment of nAMD. In line with departmental protocols, one raster line (530 A-scans x 50 lines) and one radial line (2122 A-scans x 6 lines) scan set were acquired in a single imaging session. An ophthalmologist experienced in clinical trials work analyzed the radial lines for sub-retinal fluid (SRF), intra-retinal cysts (IRC), diffuse retinal edema (DRE), pigment epithelial detachment (PED) and sub-retinal tissue (SRT) and then analyzed the raster lines 1 week later with masking of patient details. The patients were at different stages of treatment and disease activity.
There were OCT features of CNV activity present in raster and radial line scans of all 30 patients. However, raster line scanning detected additional OCT features of CNV activity in 9 patients (30%) compared to the radial line scans. The additional OCT features detected were SRF in 2 patients (7%), IRC in 2 patients (7%), DRE in 4 patients (13%), PED in 2 patients (7%) and SRT in 2 patients (7%). Five patients (17%) had more than one feature detected on raster line but absent on radial line scans.
This is the first study to investigate the theoretical advantage of raster line scanning protocols over radial line scans in detecting OCT features of CNV activity. This study suggests that raster line scanning protocols may be better in detecting CNV activity than radial line OCT scanning protocols with implications for retreatment with anti-VEGF agents. Further larger studies are needed to investigate this further.
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