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Teruhiko Hamanaka, Tomohiko Higashida, Tetsuro Sakurai, Nobuo Ishida; The compatibility of the location of scleral spur in the observation of anterior segment optical coherence tomography and histological examination. Invest. Ophthalmol. Vis. Sci. 2014;55(13):938.
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Angle-structure data obtained by anterior segment optical coherence tomography (AS-OCT) plays an important role for evaluating the risk for primary angle-closure glaucoma (PACG). For angle-structure evaluation, scleral spur (SS) is a fundamental point for various parameters; e.g., angle opening distance (AOD) and trabecular-iris space area (TISA). However, SS in AS-OCT images is mostly unclear and difficult to detect. In this study, we evaluate the compatibility in the detection of SS observed by AS-OCT and histological examination of trabeculectomy (TLE) specimens.
Angle structure images were obtained from 38 open-angle glaucoma eyes and 12 angle-closure glaucoma eyes pre and post TLE by AS-OCT (Visante OCT; Carl Zeiss Meditec, Dublin, CA, Casia SS-1000, Tomey Corp., Nagoya, Japan). TLE specimens were embedded in paraffin and processed for hematoxylin-eosin (HE), Masson trichrome, and thrombomodulin immunohistochemical staining. Locations of bottom of the angle recess (BAR) and SS (on the border line of ciliary body and sclera) were input on the printed AS-OCT image (Figure. SS: arrowhead, BAR: arrow; top left inset). On the histological image, the location of Schwalbe’s line (SW) (Figure, solid arrowhead), SS (Figure, open arrowhead), BAR (Figure, arrow), and anterior and posterior tips of the Schlemm’s canal (SC) (Figure) were also input, and then the distance of SW-SS and SS-BAR were measured. SS defined to input the most bulging part of SS. The development of SS was categorized into 4 grades [grades 0 (less) to III (prominent)]. All histological images were inserted into the defective area of the post-TLE AS-OCT images (Figure, top right inset).
All SS on the AS-OCT images were located 218±147µm (mean±SD) posterior to BAR. On the histological images, SS was located anteriorly (50%) and posteriorly (50%) to BAR (6±98µm). The distance between SW and SS was 612±83µm. The length of SC was 233±61µm. The ratio of the development grades of SS were as follows: 0: 25%, I: 50%, II: 9%, III: 16%). The development of SS was significantly correlated with SS-BAR.
SS could not be precisely detected by any type of AS-OCT, and SS on AS-OCT images tended to be input more posteriorly to BAR. The angle recession, which indicates BAR, may be located more posteriorly in eyes with developed SS.
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