Xinting Liu

Repeatability and Reproducibility of Eight Macular Intra-Retinal Layer Thicknesses Determined by an Automated Segmentation Algorithm Using Two SD-OCT Instruments

Purpose To evaluate the repeatability, reproducibility, and agreement of thickness profile measurements of eight intra-retinal layers determined by an automated algorithm applied to optical coherence tomography (OCT) images from two different instruments. Methods Twenty normal subjects (12 males, 8 females; 24 to 32 years old) were enrolled. Imaging was performed with a custom built ultra-high resolution OCT instrument (UHR-OCT, ∼3 µm resolution) and a commercial RTVue100 OCT (∼5 µm resolution) instrument. An automated algorithm was developed to segment the macular retina into eight layers and quantitate the thickness of each layer. The right eye of each subject was imaged two times by the first examiner using each instrument to assess intra-observer repeatability and once by the second examiner to assess inter-observer reproducibility. The intraclass correlation coefficient (ICC) and coefficients of repeatability and reproducibility (COR) were analyzed to evaluate the reliability. Results The ICCs for the intra-observer repeatability and inter-observer reproducibility of both SD-OCT instruments were greater than 0.945 for the total retina and all intra-retinal layers, except the photoreceptor inner segments, which ranged from 0.051 to 0.643, and the outer segments, which ranged from 0.709 to 0.959. The CORs were less than 6.73% for the total retina and all intra-retinal layers. The total retinal thickness measured by the UHR-OCT was significantly thinner than that measured by the RTVue100. However, the ICC for agreement of the thickness profiles between UHR-OCT and RTVue OCT were greater than 0.80 except for the inner segment and outer segment layers. Conclusions Thickness measurements of the intra-retinal layers determined by the automated algorithm are reliable when applied to images acquired by the UHR-OCT and RTVue100 instruments.

Macular Thickness Profiles of Intraretinal Layers in Myopia Evaluated by Ultrahigh-Resolution Optical Coherence Tomography.

PURPOSE To investigate the thickness and variation profiles of 8 intraretinal layers in myopia. DESIGN Prospective cross-sectional study. METHODS Young subjects with spherical equivalents ranging from +0.50 to -10.25 diopters and good corrected vision were divided into emmetropic (n = 20), low myopic (n = 50), and high myopic (n = 30) groups. Retinal images centered on the fovea along the horizontal and vertical meridians were obtained by ultrahigh-resolution optical coherence tomography (OCT). Macular images were segmented into 8 intraretinal layers by an automatic segmentation algorithm to yield thickness profiles within a 6-mm-diameter circle divided into central, pericentral, and peripheral regions. RESULTS For intraretinal layers in the central region, the outer segment of receptors layer was thicker in the high myopic group and positively correlated with axial length. In the pericentral and peripheral regions, all layers except the ganglion cell and inner plexiform layer had thickness changes in high myopia. The total thickness of the peripheral region was less than in the emmetropic controls owing to thinner inner nuclear layer, combined Henle fiber and outer nuclear layer, and outer segment of receptors layer. Nevertheless, the thicknesses of the combined myoid and ellipsoid zone and the combined interdigitation zone and retinal pigment epithelium/Bruch complex in the peripheral region were greater than for the emmetropic controls. CONCLUSIONS Intraretinal layer thicknesses in young high myopic eyes varied significantly from emmetropic controls, especially in the peripheral region. Ultrahigh-resolution OCT with automated segmentation can detect changes in retinal macular microstructure during the development of myopia.

Ultra-high resolution profiles of macular intra-retinal layer thicknesses and associations with visual field defects in primary open angle glaucoma

The structural characteristics of the outer retinal layers in primary open angle glaucoma (POAG) are still controversial, and these changes, along with those in the inner retinal layers, could have clinical and/or pathophysiological significance. A custom-built ultra-high resolution optical coherence tomography (UHR-OCT) combined with an automated segmentation algorithm can image and measure the eight intra-retinal layers. The purpose of this study is to determine the thickness characteristics of the macular intra-retinal layers, especially the outer layers, in POAG patients. Thirty-four POAG patients (56 eyes) and 33 normal subjects (63 eyes) were enrolled. Thickness profiles of the eight intra-retinal layers along a 6-mm length centred on the fovea at the horizontal and vertical meridians were obtained and the regional thicknesses were compared between two groups. The associations between the thicknesses of each intra-retinal layer and the macular visual field (VF) sensitivity were then analysed. POAG affected not only the inner retinal layers but also the photoreceptor layers and retinal pigment epithelium of the outer retina. However, the VF loss was correlated mainly with the damage of the inner retinal layers. UHR-OCT with automated algorithm is a useful tool in detecting microstructural changes of macula with respect to the progression of glaucoma.

THREE-DIMENSIONAL CHARACTERISTICS OF FOUR MACULAR INTRARETINAL LAYER THICKNESSES IN SYMPTOMATIC AND ASYMPTOMATIC CARRIERS OF G11778A MUTATION WITH LEBER'S HEREDITARY OPTIC NEUROPATHY.

Purpose: To characterize by spectral domain optical coherence tomography the three-dimensional thicknesses of four macular intraretinal layers in symptomatic and asymptomatic carriers of G11778A mutation with Lebers hereditary optic neuropathy. Methods: Twenty-five eyes (7 symptomatic eyes and 18 asymptomatic eyes) of patients with Lebers hereditary optic neuropathy from one Chinese family and 16 normal eyes were enrolled. Macular radial scans by spectral domain optical coherence tomography and custom software produced intraretinal three-dimensional thickness maps. The macula was divided into nine regions, and each region included four intraretinal layers: nerve fiber layer, ganglion cell layer and inner plexiform layer, inner nuclear layer and outer plexiform layer, and the outer retinal layer. Results: Nerve fiber layer in the symptomatic eyes was significantly thinner than in normal eyes for most of the macular regions; however in the asymptomatic eyes, it was increased in three regions. Ganglion cell layer and inner plexiform layers in all regions of symptomatic eyes were significant thinner than in asymptomatic eyes and controls. Inner nuclear layer and outer plexiform layers in six regions of symptomatic and asymptomatic eyes were significantly thicker than in controls. The outer retinal layer of asymptomatic eyes was thicker than in most control regions. Conclusion: Intraretinal thickness changes in asymptomatic patients could be prodromal events that indicate the imminent conversion to symptomatic patients with Lebers hereditary optic neuropathy.