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Mauro Campigotto, Anna Paviotti, Andrea De Giusti, Lorenzo Cappellari; Irido-corneal angle visualization in automated gonioscopy. Invest. Ophthalmol. Vis. Sci. 2018;59(9):5868.
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In conventional gonioscopy, only a limited portion of the irido-corneal angle can be examined at a time, and the way features are visualized entirely depends on the type of lens used to perform the exam. NIDEK GS-1, a novel gonioscopy device (NIDEK CO., Japan), acquires true color digital images of the irido-corneal angle covering 360°, allowing more flexibility in the visualization of eye features. The aim of this work is to explore different ways of visualizing the exam data acquired by GS-1.
In GS-1, a prism with 16 mirroring facets is used to acquire the angle. Each facet covers about 30°, and the images are acquired as if performing indirect gonioscopy with a Goldmann lens. Numbers from 0 to 15 were used as markers to annotate an acquired image set (OD). Each number indicates the facet used to acquire the corresponding image, and is mirrored as if acquired through the device (Fig. 1). We have combined the acquired images in 3 different ways to see the angle as a whole. The first way is to stitch the images into a linear panorama with the iris on the lower side (“linear stitching”, Fig. 2a). This is the most geometrically sound representation, since the irido-corneal angle is similar to the internal surface of a ring, which can be exactly linearized. An alternative is to create a 360° circular view of the angle, choosing the coordinate mapping so that the images are seen as in direct gonioscopy (“circular stitching”, Fig. 2b). Another possibility is to create a “virtual goniogram” (Fig. 2c), stitching together only the images referring to the same quadrant (Superior, Nasal, Inferior, Temporal). This is similar to performing a wide-angle indirect gonioscopy.
Linear stitching gives the most faithful representation of the acquired data and allows to easily annotate the angle features. Circular stitching corrects the mirroring effects and allows seeing the eye features and possible MIGS drainage implants in the correct location and with the correct orientation in space. Virtual goniogram can be useful for Becker’s goniogram chart-like clinical annotations.
Automated gonioscopy by NIDEK GS-1 allows great flexibility in the presentation of the acquired data. Classical representations as well as new visualizations of the irido-corneal angle can be created. A clinical evaluation is needed to assess the clinical advantages of each representation, and to collect suggestions for new ones.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.
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