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Ryan P McNabb, Robin Raul Vann, Joseph A Izatt, Anthony N Kuo; Ocular morphometry from wide-field, whole eye OCT compared to MRI and PCI. Invest. Ophthalmol. Vis. Sci. 2017;58(8):5448.
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© ARVO (1962-2015); The Authors (2016-present)
Ocular morphometry (or biometry) is an important part of clinical care, such as cataract surgical planning, and in research where eye shape from MRI has been correlated with pathological myopia. While widely used in ophthalmology, optical coherence tomography’s use in ocular morphometry has generally been limited due to technical and optical constraints in imaging the eye as a whole. We describe here the development of a “whole eye” OCT system that overcomes these constraints to simultaneously image full views of the anterior chamber and 50° on the retina (macula + optic nerve) and provide ocular morphometry.
A tabletop 200kHz swept source (λ0=1045nm; Axsun, Inc.) OCT system with a polarization encoded, dual channel sample arm was developed to simultaneously image both the anterior and posterior eye in a single volume (Fig. A-E). Four subjects (N = 8 eyes) were consented under an IRB approved protocol to have “whole eye” OCT volumes, and for comparison, also have PCI (LenStar, Haag-Streit) and MRI (1mm T1; MR 750 3.0 T, GE, Inc.). For morphometric analysis, OCT images were segmented, corrected for subject and system optical distortions, and oriented correctly in a virtual space (Fig. F). Retinal curvature (Rc) and axial length (AL) from OCT were compared to MRI and PCI respectively. Non-parametric Wilcoxon sign rank test was used for statistical analysis.
Curvature measured by whole eye OCT (Rc= 11.49±0.59mm) compared to MRI (Rc= 11.11±0.33mm) was not statistically significantly different (ΔRc = -0.38±0.62mm, p = 0.219). Axial length measured by whole eye OCT (AL = 23.13±0.87mm) compared to PCI (AL = 23.19±0.76mm) was also not statistically different (ΔAL = 0.063±0.288, p = 0.557).
We demonstrated a wide-field, whole eye OCT system capable of simultaneously providing quantitative morphometric analysis of ocular tissue within a single volume acquisition that is not statistically significantly different from MRI and PCI. This has important clinical implications for OCT as a complete platform to both examine layered microstructure and for ocular morphometry analysis.
This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.
A) Whole eye OCT imaging system schematic B&C) Averaged B-scan dispersion corrected for posterior and anterior segment respectively D&E) Simultaneously acquired volumes of anterior and posterior segment F) Whole eye OCT B-scan distortion corrected for morphological analysis G) T1 MRI cross-section of same eye as F for comparison
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