Abstract
Purpose: :
To compare the thickness measurements between spectral domain (Topcon 3DOCT 1000, SDOCT) and time domain (Stratus, TDOCT) optical coherence tomography in various retinal diseases and assess the relationship between central subfield thickness measurement and visual acuity (VA).
Methods: :
Patients requiring OCT scans for standard care assessment of retinal disease were recruited for the study. Scans were obtained on the SDOCT machine using a 6 x 6 mm, 512 x 128 B scan protocol and the fast macular thickness scanning protocol on the TDOCT. Scan quality was assessed to determine accuracy of retinal thickness measurements in the map reports. With the SDOCT software, two map reports were generated: one using the retinal pigment epithelial layer (RPE) as the outer boundary and another using photoreceptor inner segment outer segment (IS-OS) junction as the outer boundary. The latter is similar to the segmentation algorithm of TDOCT.
Results: :
Quality assessment of 136 pairs of SDOCT and TDOCT scans (73 patients) retrieved 91 pairs of scans with accurate central subfield (CSF) thickness measurements. The mean difference in CSF thickness between SDOCT and TDOCT was 24.6µm (SD=21.9µm, p<0.01). The mean difference between the instruments was significantly smaller (7.4 µm, p<0.01) when the IS-OS junction was used as the outer boundary line in SDOCT. Pearson correlation coefficients between Snellen LogMAR VA and the CSF thickness measured by SDOCT and TDOCT were 0.43 and 0.48, respectively.
Conclusions: :
Retinal thickness measurements in the CSF vary between SDOCT and TDOCT primarily due to the difference in the outer retinal layer segmentation algorithm. For this sample with various retinal diseases and good quality scans, the central subfield thickness has a modest association with VA for both instruments.
Keywords: clinical research methodology • imaging/image analysis: clinical • imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound)