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Musa Abdelaziz, Claes H Dohlman, Rony R Sayegh; Glare Reduction Strategies for Keratoprosthesis. Invest. Ophthalmol. Vis. Sci. 2015;56(7 ):1121.
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© ARVO (1962-2015); The Authors (2016-present)
Significant glare is frequently reported by patients after Boston keratoprosthesis (KPro) surgery. An opaque contact lens is helpful but potential movement of the lens limits its usefulness in many patients. We explore the effect of various modifications to the KPro assembly on glare.
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 sand-blasted scattering Boston 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 (focal length, 14.8 mm in air). Point-spread function (PSF) curves with corresponding area under the curve (AUC) were derived using Matlab.
A tight PSF curve was obtained with the KPro surrounded by an opaque iris (control, AUC 3.3). A wider PSF curve (more glare) was noted with the use of a PMMA back plate (AUC 5.3) compared with the newer titanium back plate (AUC 4.4). The addition of a +2.00D acrylic intraocular lens placed behind the KPro with titanium back plate did not increase scatter (AUC 4.2). The use of a modified titanium locking-ring that is 6mm in diameter eliminated scatter and resulted in a PSF similar to the control (AUC 3.3). Maximal scatter was noted with KPro front plate inserted in the sand-blasted scleral lens (AUC 11.3).
The newer titanium back plate provides better glare protection compared to its older PMMA counterpart. There is no difference in measured glare between pseudophakic and aphakic KPros. Modification of the locking ring design may be an effective strategy to reduce glare.
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