The measurement repeatability using different partition methods of intraretinal tomographic thickness maps in healthy human subjects

Abstract

PurposeTo determine the repeatability and profiles with different partition methods in intraretinal thickness layers in healthy human subjects, using optical coherence tomography (OCT).MethodsA custom-built ultrahigh-resolution OCT was used to acquire three-dimensional volume of the macula in 20 healthy subjects. The dataset was acquired twice using the macular cube 512×128 protocol in an area of 6×6 mm2 centered on the fovea. Commercially available segmentation software (Orion™) was used to segment the dataset into thickness maps of six intraretinal layers. The coefficient of repeatability and intraclass coefficient of correlation (ICC) were analyzed using hemispheric zoning and sectors defined by the Early Treatment Diabetic Retinopathy Study (ETDRS).ResultsAll datasets were successfully segmented to create six thickness maps of individual intraretinal layers. Coefficients of repeatabilities of these layers in hemispheric zones ranged from 0.9 to 6.6 µm, with an average of 3.6 µm (standard deviation [SD] 1.4), which was not significantly different compared to ETDRS sectors (P>0.05). ICCs of these layers in hemispheric zones ranged from 0.68 to 0.99, with an average of 0.91 (SD 0.07). There were no significant differences in ICCs between two zoning methods (P>0.05). Significant variations of tomographic intraretinal thicknesses were found between the inner and outer annuli and among the quadrantal sectors within the inner and outer annuli (P<0.05). Significant variations of the quadrantal sectors including both inner and outer annuli were evident in intraretinal layers (P<0.05) except for the outer plexiform layer.ConclusionThe measurement repeatabilities of tomographic thicknesses of intraretinal layers are comparable using both hemispheric and ETDRS partitions in volumetric data combined with the commercially available segmentation software. In keeping with known, normal anatomical variation, significant differences in tomographic thickness in various intraretinal layers were apparent in both hemispheric and ETDRS sectors.

Age-Related Alterations in the Retinal Microvasculature, Microcirculation, and Microstructure

“…18 The macular cube was automatically segmented (Fig. 5) to obtain the total retinal thickness (TRT) and six intraretinal maps, including the RNFL, GCIPL (GCL + IPL), INL, OPL, ONL, and photoreceptor complex (PR).…”

Focal Thickness Reduction of the Ganglion Cell-Inner Plexiform Layer Best Discriminates Prior Optic Neuritis in Patients With Multiple Sclerosis

“…As described previously, 16,17,20 the custom UHR-OCT system is a spectral domain OCT with an axial resolution of~3 lm in tissue and a scan speed of 24,000 A-scans per second. The scan pattern was a raster scan with 512 A-scans (per B-scan) 3 128 B-scans, which covered a field of view of 6 3 6 mm centered on the fovea.…”

“…The scan data set was exported and segmented using an automatic image processing software program (Orion, Voxeleron LLC, Pleasanton, CA, USA). 17 Segmentation of all intraretinal layers of the horizontal scan (fast scan) and the vertical scan (slow scan) crossing the foveal center, and the thickness map of the total retina were exported and saved as a record for segmentation verification. However, the segmentation of each Bscan was not checked.…”

“…However, it is hard to exclude subclinical ON clinically, which occurs with high incidence in patients with MS. [3][4][5] The averaged thicknesses of the GCIPL and pRNFL that are used in intereye approaches 11,13,14 may not be sensitive enough to identify optic nerve damage. Because the distribution of the neural fiber and ganglion cells are not even, [15][16][17] and the alterations in these neural layers are not even. 15,16 The average thicknesses of these layers using arbitrary partitions, such as the elliptical partition, which is commonly used in the clinic, may not well define the focal thickness alterations 11,13,14 and could render the moderate discrimination power when using the intereye thickness difference approach.…”

Changes in volume of various retinal layers over time in early and intermediate age-related macular degeneration

“…Recently, automated segmentation software programmes that enable analysis layers of the retina qualitatively and quantitatively have been introduced [15,16]. Using these softwares, recent studies of AMD eyes have demonstrated that there were a change not only in the outer retinal layers as previously established but also in the inner retina such as the ganglion cell complex (GCC) thickness, which includes GCL and inner plexiform layer (IPL) [17][18][19][20][21].…”