In vivo imaging of lamina cribrosa pores by adaptive optics scanning laser ophthalmoscopy.
ABSTRACT To visualize and assess the surface-level pores of the lamina cribrosa in patients with glaucoma by using a prototype adaptive optics scanning laser ophthalmoscopy (AOSLO) system.
The numbers of laminar pores were compared between color disc photography, scanning laser ophthalmoscopy (SLO) without AO, and AOSLO. The pore area and elongation index were examined for correlation with ocular parameters such as the mean deviation, disc area, cup/disc ratio, disc ovality index, intraocular pressure (IOP), and axial length in the AOSLO images.
The 40 eyes (20 normal and 20 glaucomatous) of 40 subjects were enrolled. The AOSLO provided laminar pore images of better quality than other imaging methods, and the number of visible pores was significantly greater in the AOSLO images than in the other imaging methods (the color disc photographs [P < 0.001] and SLO without AO images [P < 0.001]) when compared for 26 subjects. When compared for 40 subjects using AOSLO, the pore area was significantly larger in glaucomatous subjects than in normal subjects (P = 0.031), but elongation index was not. The pore area correlated significantly with the axial length (P = 0.008) in normal subjects, with the untreated IOPs (P = 0.002) in the glaucomatous subjects, and with the axial length (P = 0.001) and cup/disc ratio (P = 0.012) in the total subjects. Via multiple regression analysis, significant correlations with pore area were found for axial length in the normal (β = 0.684, P = 0.001) and total subjects (β = 0.496, P < 0.001) and untreated IOP in the glaucomatous (β = 0.506, P = 0.023) and total subjects (β = 0.331, P = 0.014).
AOSLO is a useful imaging technology for assessing laminar pore morphology. The laminar pore area may be affected by axial length and IOP.
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ABSTRACT: Glaucoma is the leading cause of preventable blindness in the western world. Investigation of high-resolution retinal nerve fiber layer (RNFL) images in patients may lead to new indicators of its onset. Adaptive optics (AO) can provide diffraction-limited images of the retina, providing new opportunities for earlier detection of neuroretinal pathologies. However, precise processing is required to correct for three effects in sequences of AO-assisted, flood-illumination images: uneven illumination, residual image motion and image rotation. This processing can be challenging for images of the RNFL due to their low contrast and lack of clearly noticeable features. Here we develop specific processing techniques and show that their application leads to improved image quality on the nerve fiber bundles. This in turn improves the reliability of measures of fiber texture such as the correlation of Gray-Level Co-occurrence Matrix (GLCM).Biomedical Optics Express 06/2014; 5(6):1941-51. · 3.50 Impact Factor
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ABSTRACT: Purpose: To characterize the in vivo 3D lamina cribrosa (LC) microarchitecture of healthy eyes using adaptive optics spectral-domain optical coherence tomography (AO-SDOCT). Methods: One randomly selected eye from each of 18 healthy subjects was scanned with Cirrus HD-OCT and AO-SDOCT centered on the optic nerve head. LC microarchitecture, imaged by the later device, was semi-automatically segmented and quantified for connective tissue volume fraction (CTVF), beam thickness, pore diameter, pore area and pore aspect ratio. The LC was assessed in central and peripheral regions of equal areas, quadrants and with depth. A linear mixed-effects model weighted by the fraction of visible LC was used to compare LC structure between regions. Results: The nasal quadrant was excluded due to poor visualization. The central sector showed greater CTVF and thicker beams as compared to the periphery (p<0.01). There was no statistically significant difference between superior and inferior quadrants for any parameter. Both superior and inferior quadrants showed greater CTVF, pore diameter, and pore mean area than the temporal quadrant (p<0.05). Depth analysis showed the anterior and posterior aspects of the LC contained smaller pores with greater density and thinner beams as compared to the middle third (p<0.05). The anterior third also showed a greater CTVF than the middle third (p<0.05). Conclusions: In vivo analysis of healthy eyes using AO-SDOCT showed significant, albeit small, regional variation in LC microarchitecture by quadrant, radially, and with depth, which should be considered in further studies of the LC.Investigative Ophthalmology & Visual Science 09/2014; · 3.66 Impact Factor
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ABSTRACT: The aim of this study was to demonstrate the fine laminar structure of the optic nerve head (ONH), in vivo, using a broad wavelength, ultra-high resolution, and optically coherent tomography (OCT) system. This high-resolution OCT system, based on a 200 nm bandwidth spectrometer and an 8 femtosecond ultra-short, mode-locked, coherent laser light source, enabled in vivo cross-sectional ONH imaging with 2.0 μm axial resolution. A total of 300 optic disc B-scans, which consisted of 300 × 2048 pixels, were obtained in 10 μm steps. Three-dimensional images were rendered from these images to obtain n face images of the optic disc. Fundus photography, scanning laser ophthalmoscopy (SLO), and standard OCT were also performed for all subjects. Thirty-six eyes of normal subjects and ten eyes of glaucoma patients with mean age of 40.0 ± 10.0 years were enrolled in this study. Sequential en face images, from the ONH surface to deeper layers, were reconstructed in 2.0 μm steps. Observation of the images indicated variations in the shape and arrangement of the lamina pores at different depths. Clear lamina pores were identified by this technique in 44 eyes, compared with the fundus camera (identified in six eyes), SLO (identified in 14 eyes), and standard OCT (identified in 24 eyes) (all comparisons, p < 0.001). The fine structure of the ONH could be resolved in vivo using our OCT, providing improved imaging that can be used in research and clinical applications for a better characterization of the anatomical and pathological features associated with glaucoma.Albrecht von Graæes Archiv für Ophthalmologie 12/2014; · 2.33 Impact Factor