Abstract
Purpose: :
Spectral OCT scanning greatly improves the image quality of the cross sectional retinal images over conventional OCT scanning. Color displays are an attempt to incorporate a wider dynamic range into scans versus gray scale imaging. The displayed colors however are false colors and the observer may see a dramatic change in color and interpret that as a large change in the OCT reflectivity. We wished to determine whether color or gray scale images of the ultrahigh resolution spectral OCT are superior in visualizing clinically important details of the retinal structures.
Methods: :
50 eyes of 42 patients with macular pathologies and 18 control eyes were imaged using Spectral OCT (OTI Inc, Toronto, Canada) at the Jacobs Retina Center, UCSD, CA. Two reviewers independently analyzed the retinal structures and pathologies including drusen, photoreceptor layer, RPE layer, ERM, posterior hyaloid and intraretinal/subretinal fluid and graded them on a 4-point scale scale of (0-III) on the basis of the visibility. A third reviewer masked to the results then reviewed images where there was a discrepancy in the grading scale.
Results: :
Interobserver correlation was high (r = 0.823042, p value <0.05) Statistical analysis showed significant differences in visualizing the photoreceptor layer morphology between gray and color scale. (Mean: 2.3 +/- 0.76 vs. 1.91 +/- 0.85 respectively, p<0.0030). Although ERM and the RPE layer were seen on both, the details were better appreciated on the gray scale. In 16.17 % of eyes color image led to the false impression of photoreceptor disruption . This was confirmed by the third masked reviewer.
Conclusions: :
Gray scale is superior to the color scale in identifying subtle retinal features such as IS/OS junction, ELM, details of ERM. The use of the gray scale instead of the color scale enhances the visualization of intraretinal morphology because of its finer monotone gradation and therefore provide additional diagnostically important information
Keywords: imaging/image analysis: clinical • retina • imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound)