Abstract
Purpose:
To assess circumpapillary retinal vessel thickness (cRVT) profiles and correlate them with retinal nerve fiber layer (RNFL) thickness measured by high resolution optical coherence tomography (HR-OCT) and scanning laser polarimetry (SLP).
Methods:
A sample of 106 healthy volunteers underwent complete ophthalmologic examination, including HR-OCT scanning (Cirrus® Carl Zeiss Meditec Inc.) and SLP (GDx-VCC® and GDx-ECC ® Carl Zeiss Meditec Inc.). A proprietary software was developed in MATLAB® (Version R2009b, The Mathworks Inc.) for individual manual assessment of the optic disc (OD) border and cRVT, using the SLO image from Cirrus HR-OCT centered in the OD. For each measurable vessel, we established a line connecting its center point at the OD border with the OD center. The angle between this line and a horizontal line passing through OD center was determined. Individual cRVT measurements were convoluted with a Gaussian window, generating a cRVT profile dependent on the number of sectors measured in each device (256 sectors for HR-OCT or 64 sectors for both GDxVCC and GDxECC). Intersubject variability was determined using MATLAB.
Results:
The median values for intersubject correlation between cRVT and RNFL thickness and the numbers of significant sectors as measured with Cirrus HR-OCT, GDx-ECC and GDx-VCC were 0.255 (186/256 sectors statistically significant), 0.192 (32/64) and 0.195 (33/64). 90% percentiles of the intersubject correlation were 0.400, 0.355 and 0.336, respectively.
Conclusions:
Both SLP methods (GDx-VCC and GDx-ECC) yield comparable results regarding the intersubject correlation of the cRVT profile and the RNFL with about 50% of the sectors showing significant correlation. However, regarding the HR-OCT, our data showed a tendency towards a better correlation which was statistically significant in 70% of the sectors. Based on our results, up to 25% of the interindividual variation of the RNFL thickness might be explained by the variation of the cRVT.
Keywords: 610 nerve fiber layer •
552 imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) •
550 imaging/image analysis: clinical