Fig 1.
Regions where radial peripapillary capillary network morphology and topography were studied quantitatively.
Insets placed on a fluorescein angiogram illustrate the six different eccentricities that were studied with speckle variance optical coherence tomography and histology. Sup = Superior; ST = Supero-temporal; Temp = Temporal; IT = Infero-temporal; Inf = Inferior and N = Nasal regions.
Fig 2.
Methodology for quantitative measurements.
Representative speckle variance optical coherence tomography (svOCT) image (A) and histology image (B) from the nasal peripapillary region illustrates the technique used to acquire quantitative measurements. Capillary density was determined by calculating the number of intersections between capillaries (circles) and a perpendicular, straight line (red line) drawn through the capillary network. Results were expressed as intersections per 100 μm. Capillary diameter was determined by calculating the perpendicular distance across the maximum chord axis of each vessel. This is as illustrated in the corresponding magnified regions (outlined in yellow dashed lines) of svOCT (C) and histology (D) images. Scale bar = 120μm (A & B) and 60μm (C and D)
Fig 3.
A paired graphical representation of quantitative comparisons between speckle variance optical coherence tomography (svOCT) and histology data for the six eccentricities.
The averaged value is presented as solid bars with standard deviations presented by error bars. Black solid bars represent data from svOCT images whilst grey solid bars represented data from confocal images. Data presented include (A) number of RPCs per 100 μm, (B) Inter-capillary distance or ICD in microns, and (C) RPCs diameter in microns. The data are presented as per study region and include the supero-temporal (ST), infero-temporal (IT), superior (Sup), temporal (Temp), inferior (Inf) and nasal (Nasal). Statistically significant difference (p<0.05) between the two techniques are marked with an asterisk.
Fig 4.
Comparison of radial peripapillary capillary (RPC) network morphology between speckle variance optical coherence tomography and histology images.
Representative images from the six study regions obtained using svOCT and the confocal scanning laser microscope are provided. Sup = Superior; ST = Supero-temporal; Temp = Temporal; IT = Infero-temporal; Inf = Inferior and N = Nasal. Scale bar = 100 μm.
Fig 5.
Scatter plot of intercapillary distance (ICD) and retinal nerve fibre layer thickness (RNFL) with the speckle variance optical coherence tomography.
Each region is colour coded. Sup = Superior; ST = Supero-temporal; Temp = Temporal; IT = Infero-temporal; Inf = Inferior and N = Nasal. Unit of measurement in both axes is in microns.