Abstract
Purpose::
To evaluate raster images taken with extremely high resolution (6 micrometers)/ ultra high speed spectral OCT/SLO (OTI) and compare them to conventional time domain high resolution OCT (Stratus) in eyes with inner retinal pathologies.
Methods::
We evaluated 23 consecutive eyes with inner retinal pathologies and 9 controls using spectral OCT (OTI inc, Toronto, Canada) and Stratus OCT (Carl Zeiss Meditec inc. Dublin, CA). Pathologies included Macular Edema, Epiretinal Membranes, Macular Holes and Vitreo-macular traction. Images with both were compared simultaneously on two identical LCD monitors in a darkened room. We evaluated ERM texture, retinal cyst formation, extent of retinal edema, disruption of normal retina layering, posterior hyaloid detachment and points of ERM and hyaloid attachments using each instrument. Three reviewers reached consensus and also graded the pathological findings on a scale (0-III) on basis of visibility, with 0 indicating not visible.
Results::
Statistical analysis showed ERM texture visibility of X (spectral) vs Y (stratus) p= 0.0002 (Wilcoxon). For visualization of macular cystic details grading was done X vs Y p=0.0002 (Wilcoxon) and for posterior hyaloid visibility X vs Y p was 0.0223. Spectral OCT was particularly useful in the diagnosis of subtle ERM, evaluating ERM surface texture, subtle diffuse macular edema, morphology of macular cystic spaces, disordering of retinal layering, PVD and attachments of the posterior hyaloid.
Conclusions::
High speed spectral OCT-SLO allows rapid image acquisition, higher number of cuts, better sampling yeilding superior imaging of a pathology. In 39% of cases the true anatomic diagnosis was made only with spectral OCT. In the remaining pathological cases the Stratus image, although not of the same quality as OTI, was able to make the diagnosis. Inner retinal structures usually seen better with spectral OCT/SLO are ERM texture, subtle diffuse macular edema, and posterior hyaloid.
Keywords: imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) • retina • macular holes