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Takuhei Shoji, Hiroto Kuroda, Masayuki Suzuki, Hisashi Ibuki, Itaru Kimura, Makoto Araie, Shin Yoneya; Changes in the structure of lamina pores within the lamina cribrosa using wide bandwidth, femtosecond mode-locked laser optical coherence tomography; Effect of glaucoma. Invest. Ophthalmol. Vis. Sci. 2016;57(12):829.
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© ARVO (1962-2015); The Authors (2016-present)
The lamina cribrosa (LC) has been known to play a critical role in the pathogenesis of glaucomatous optic neuropathy. Deformation and relocation of pores would result in deformation of axons passing through these pores, making them further vulnerable to mechanical and/or non-mechanical damages. We compared site- and depth-dependent changes of pore shapes between glaucoma and normal eyes.
Optic nerve head B-scans were obtained using a broad wavelength optical coherence tomography with mode-locked laser with axial resolution of 1.8 μm in the air. 1, A total of 300 single B-scans per eye were obtained. Three-dimensional images were rendered from these image sequences to obtain 2-μm thin-slice en-face images of the optic disc.The elongation indexes (EIs)(the reciprocal of the ovality index, [major axis length/minor axis length]) of the lamina pores were measured from the anterior surface (AS) of the LC to the deep layer in 40-μm increments.
A total of 1112 pores from 12 primary open angle glaucoma (POAG) (median MD value=−15.30 [−13.33, −16.85] [interquartile range] dB) and 10 normal eyes were reviewed. The median of EIs were 1.55 (1.23~1.86), 1.43 (1.25~1.70) and 1.40 (1.17~1.67) in normal and 1.69 (1.36~1.23), 1.51 (1.18~2.00) and 1.36 (1.13~1.67) in POAG eyes at AS, 40 μm and 80 μm, respectively. No site- and depth-dependent difference in the EIs were found in normal eyes, while depth-dependent change in EIs was seen in POAG eyes (P<0.001). The AS and presence of POAG remained significant (P<0.05) after adjustment for other potential confounding factors such as refraction, age or site.
In POAG eyes, deformation of lamina pores (greater EIs) was more evident at more anterior layers of LC, while no depth-dependent change in EIs was seen in normal eyes.1. Kuroda H. et.al. A high speed 3-dimensional spectral domain OCT with< 2μm axial resolution using wide bandwidth femtosecond mode-locked laser. Applied Physics Letters 2013;102:251102.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.
Schematic explanation of the method of acquisition of en-face images A: fundus photo image B: The anterior surface (AS) of the lamina cribrosa (LC) is determined from a B-scan image. Depths of 40 and 80 mm are also determined from the AS images. C to E: Each en-face image of the AS of the LC (C), 40 mm from the AS (D), and 80 mm from the AS (E).
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