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Sieun Lee, Sherry Han, Mei Young, Paul Mackenzie, Mirza Faisal Beg, Marinko V Sarunic; Anterior lamina cribrosa morphometrics in myopic glaucoma. Invest. Ophthalmol. Vis. Sci. 2014;55(13):906.
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© ARVO (1962-2015); The Authors (2016-present)
To investigate anterior laminar shape characteristics in connection with age, axial length, and glaucoma severity among myopic normal and glaucomatous eyes using OCT.
32 human eyes from 17 myopic participants (7 normal, 4 unilateral glaucoma, 6 bilateral glaucoma) were imaged using a 1060nm prototype swept-source optical coherence tomography (SS-OCT) system. Bruch's membrane opening (BMO), anterior lamina insertion points (ALIP), and anterior lamina cribrosa surface (ALCS) were manually segmented. Area, eccentricity, and planarity of ALIP were measured by ellipse-fitting. The height, skew, and length of the anterior scleral canal were characterized by vertical, horizontal, and normal distances between BMO and ALIP. ALCS depth was measured from a reference plane fit to ALIP. Multiple regression analysis was performed to assess the effect of age, axial length (AL), and visual field loss quantified by mean deviation (MD). Right eyes (OD, N = 17, 10 normal, 7 glaucomatous) and left eyes (OS, N = 15, 8 normal, 7 glaucomatous) were analyzed separately, along with intereye difference.
The ALIP area was positively correlated with AL (OD: p = 0.0007, OS: p = 0.0270), and ALIP area was significantly larger than BMO area (OD: p = 0.0007, OS: p = 0.0015). ALIP and BMO ellipses were generally enlongated in the nasal-temporal / superior nasal - inferior temporal direction, and in several cases displayed saddle-like pattern in planarity measurement. The vertical, horizontal, and normal distance between BMO and ALIP centroids were not significantly correlated with any factor. The canal was consistently skewed toward the nasal direction. ALCS depth was correlated with MD (OD: p = 0.0001, OS: p = 0.0026), and with AL (OD: p = 0.0012), and in inter-eye difference, with MD only (p = 0.014). ALCS depth was also correlated with Bruch's membrane depth measured on the same datasets in our previous study (OD: p = 0.003, OS: p = 0.043). The intereye difference of ALCS depth was also correlated with the intereye difference of BM depth (p = 0.001).
In the sample of glaucoma patients, posterior bowing of the ALCS is more prominent and significant than overall posterior migration represented by the ALIP position relative to BMO. ALCS shape may be affected by axial length; this is more apparent among normal subjects. Lastly, BM "bowing" or depth (distance of BM surface from a reference plane) is correlated with ALCS depth.
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