Article

In Vivo Imaging of Lamina Cribrosa Pores by Adaptive Optics Scanning Laser Ophthalmoscopy

Department of Ophthalmology and Visual Sciences, Kyoto University Graduate School of Medicine, Kyoto, Japan.
Investigative ophthalmology & visual science (Impact Factor: 3.66). 06/2012; 53(7):4111-9. DOI: 10.1167/iovs.11-7536
Source: PubMed

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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    • "Recently, there had been an increased interest in in-vivo imaging of the LC using both OCT and scanning laser ophthalmoscopy (SLO).[6]–[9] Due to its higher axial resolution compared to SLO, OCT offer considerable advantages for 3D evaluation of the LC, being able to provide dense optical sampling of the tissue. "
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    ABSTRACT: To determine the reproducibility of automated segmentation of the three-dimensional (3D) lamina cribrosa (LC) microarchitecture scanned in-vivo using optical coherence tomography (OCT). Thirty-nine eyes (8 healthy, 19 glaucoma suspects and 12 glaucoma) from 49 subjects were scanned twice using swept-source (SS-) OCT in a 3.5×3.5×3.64 mm (400×400×896 pixels) volume centered on the optic nerve head, with the focus readjusted after each scan. The LC was automatically segmented and analyzed for microarchitectural parameters, including pore diameter, pore diameter standard deviation (SD), pore aspect ratio, pore area, beam thickness, beam thickness SD, and beam thickness to pore diameter ratio. Reproducibility of the parameters was assessed by computing the imprecision of the parameters between the scans. The automated segmentation demonstrated excellent reproducibility. All LC microarchitecture parameters had an imprecision of less or equal to 4.2%. There was little variability in imprecision with respect to diagnostic category, although the method tends to show higher imprecision amongst healthy subjects. The proposed automated segmentation of the LC demonstrated high reproducibility for 3D LC parameters. This segmentation analysis tool will be useful for in-vivo studies of the LC.
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    • "While these studies have improved understanding of laminar pore geometry in normal and diseased eyes, the size and total number of pores that could be resolved and the number of eyes in which laminar pores could be successfully imaged were limited due to the reduced lateral resolution imposed by uncorrected ocular aberrations. Adaptive optics has recently been used to correct for the eye’s optical imperfections and yield high-resolution (~2-3 μm) in vivo images of laminar pores [16–19]. Studies using adaptive optics scanning laser ophthalmoscope (AOSLO) imaging [17–19] have dramatically improved the ability to quantify anterior laminar pore geometry, but have not accounted for the curvature of the anterior lamina cribrosa surface (ALCS), i.e., the fact that en face images acquired using an AOSLO represent a 2D projection of a 3D curved surface. "
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    • "Recent imaging techniques allow us to see RGC bodies and the NFL in glaucoma patients. A very recent study has demonstrated that adaptive optic scanning laser ophthalmoscopy can visualize and assess the surface-level pores of the lamina cribrosa in patients with glaucoma (Akagi et al., 2012). Therefore, it will feasible to examine individual axons and cell bodies in glaucoma patients in the near future. "
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