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Majid Moarefi, musa abdelaziz, Claes H Dohlman, Rony R Sayegh; Characterization of forward scatter from the optical stem of the Boston Keratoprosthesis. Invest. Ophthalmol. Vis. Sci. 2016;57(12):1246.
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© 2017 Association for Research in Vision and Ophthalmology.
Disability glare is frequently reported by patients after Boston keratoprosthesis (KPro) surgery. Most of the forward scatter originates from the hazy corneal graft surrounding the KPro. In this study we explore the scatter originating from the KPro stem itself.
A custom made optical bench setup was used. A point light source (LED) of adjustable intensity and a collimator lens system were used for illumination. A black, opaque scleral lens was drilled to allow insertion of a type 1 KPro front plate. A CCD camera on a rotating arm captured the image of the point source and the surrounding scatter at different angles. The type 1 KPro used was designed for an aphakic eye (back focal length 14.8 mm in air). Point-spread function (PSF) curves with corresponding area under the curve (AUC) were derived using Matlab.
Forward scatter was detected originating from the KPro as shown by the width of the PSF curve (AUC = 3.3). Coating the stem of the KPro with black opaque material reduced the amount of scattered light and the width of the PSF curve (AUC = 1.5). Covering the back surface of the KPro stem with black tape did not completely eliminate scattered light (AUC = 0.4).
A small amount of scatter is produced by the KPro stem, presumably from the rings and scratches on the surface from manufacturing and handling, and possibly from imperfections in the PMMA material. Coating the wall of the stem with opaque material results in reduced forward scatter.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.
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