Abstract
Purpose: :
A limited number of scans compromises conventional optical coherence tomography (OCT) in estimating retinal thickness accurately. Failures of edge detection algorithms falsify the results of retinal mapping even further. High-definition-OCT (SD-OCT) is based on faster scanning rate (100 times faster) with simultaneous analysis based on spectral characteristics. We investigated and compared the thickeness of retina using both instruments
Methods: :
22 eyes normal healthy volunteers (age ranging from 22 to 66) were imaged using a conventional time domain stratus OCT and high frequency (40khz) spectral-domain, high-speed high resolution Spectralis. Axial resolution was 6 µm; scanning speed was 25 kA-scans/second. Two different scanning patterns covering an area of 6x6mm in the macular retina were compared.
Results: :
Detailed information about layer-specific distribution and volumetric measurements were obtained for retinal- and sub-RPE volumes with spectralis. Both raster scans show a high correlation (p<0.01;R2>0.89) of measured values of retinal volume and mean retinal thickness. Retinal thickness could be subdivided into three separte complexes (ganglion cell layer thickness, RPE-IS/OS complex and OS-NFL thickness). True track image technology improved repeatability of measurments (95% repeatability)
Conclusions: :
Automatic segmentation allowed for detailed quantitative and topographic analysis of the RPE and the overlying retina. Accurate measurement of various segments of retina is relvevant and useful in a variety of retinal disorders both in diagnosis and in evaluation of theraupetic response to various pharmacological agents.
Keywords: retina: distal (photoreceptors, horizontal cells, bipolar cells) • imaging/image analysis: clinical • imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound)