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R Daniel Ferguson, Yang Lu, Mircea Mujat, Gopi N Maguluri, Nicusor Iftimia, James D Akula, Hanna De Bruyn, Anne B Fulton; Dual-conjugate SSOCT Whole Eye Biometry System (WEBS). Invest. Ophthalmol. Vis. Sci. 2019;60(9):1300.
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© ARVO (1962-2015); The Authors (2016-present)
To demonstrate a new reflective optical design approach to ultra-wide field, dual-conjugate SSOCT for simultaneous anterior and posterior optical biometry with refractive modeling.We report preliminary WEBS imaging results and performance from the first clinical study in progress at Boston Children's Hospital (BCH).
We have created a new prototype clinical platform for ultra-wide field optical biometry in the human eye based on a novel double-ellipsoidal reflective optical design. The platform uses a single 100kHz 1060nm swept laser source with two separate imaging channels independently focused and efficiently combined along a single, spherical-polar scan direction. The scan-pivot location can be positioned at precisely known depth with respect to the corneal surface. Automatic inter-scan focal corrections are made during volumetric scans. A high-speed dual-channel digitizer permitted imaging over a depth range of up to 8mm in each channel with 25mm spans. A novel fixation scheme allows gaze positioning. Subects were imaged at BCH in accordance with an IRB-approved imaging protocol. ANSI power levels were 3mW (corneal) and 1.5mW (retinal).
An initial imaging protocol was tested in four normal volunteers and two patients. A guiding CCD camera roughly centered the scan pivot on the cornea. In the alignment mode ("fast-scan"), the pivot was axially positioned at a known depth and in the lateral dimensions with live central x- and y-meridians. Up to 100 transverse meridian B-scans of 3200 A-scans each were captured over visual angles of 90° superior-to-inferior and 120° nasal-to-temporal. Each volume is acquired in less than 3 seconds--more rapidly with sparser scans for basic biometry. Focal depths and delay lines were adjusted to capture other pairwise ocular interfaces (e.g., lens). The SSOCT volumes thus obtained are segemented and surfaces are transformed to cartesian coordinates in post-processing with refractive corrections for physical representations of ocular shapes.These shapes will be compared to ocular MRI images obtained in a subset of subjects.
The WEBS platform will enable routine, reproducible biometric characterization of the human eye over very wide angles which is suitable for longitudinal investigations and monitoring of many ocular conditions that affect the development and shape of the anterior and posterior segments over time.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.
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