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Conor Leahy, Keith O'Hara, Jennifer Yen Luu, Jochen Straub; Usability of slit-scan ophthalmoscopes for ultra-wide-field retinal montages. Invest. Ophthalmol. Vis. Sci. 2016;57(12):4644.
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© ARVO (1962-2015); The Authors (2016-present)
To demonstrate the usability and value of a simple technique for obtaining high-quality, high-resolution true color ultra-wide-field images of the retina, by combining 80° fundus images acquired with a slit-scan ophthalmoscope.
Two 80° fundus images were acquired without mydriasis, using a custom prototype slit-scan ophthalmoscope fundus imaging system (ZEISS, Germany). The overlap between images was approximately 40° centered on the foveal region. The size and location of the overlap were controlled using a fixation target. Imaging conditions included several aspects that commonly degrade ultra-wide-field fundus images, including small pupils and scattering from the anterior segment. Retinal montages were constructed using an intelligent, semi-automated image stitching and blending algorithm.
Fundus montages spanning approximately 120° in width are presented for subjects with healthy retinas (Figure 1A). Measurements on a graded test eye are also shown, demonstrating the consistency of image quality across the full field of view (Figure 1B). Acquisition speed for subjects without mydriasis is limited by pupil recovery time after the flash, but is generally under two minutes given the small pupil capability of a slit-scan ophthalmoscope.
The simple montaging technique using slit-scan ophthalmoscope images allows for ultra-wide-field retinal acquisitions, while circumventing problems of heavy distortion and vignetting that are commonly associated with direct ultra-wide-field fundus imaging techniques. In capturing a large proportion of the retinal area with consistently high image quality, this approach may prove beneficial to clinicians, particularly in the diagnosis and monitoring of diabetic retinopathy and other ischemic conditions of the retina.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.
Figure 1. (A) Montage of two 80° fundus images (spanning approximately 120° in total) centered on the foveal region for a healthy subject; (B) Montage of two images of a graded test eye. The scale bar shows the incremental visual field angle (each concentric circle represents approximately 5°).
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