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Lauren Gabra, Samir I Sayegh, Optimal surgical outcomes group; Comparing toricity ratios across leading toric IOL manufacturers. Invest. Ophthalmol. Vis. Sci. 2015;56(7 ):1916.
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© ARVO (1962-2015); The Authors (2016-present)
To determine the toricity ratio for toric intraocular lenses for leading toric IOL manufacturers
High, average and low axial length values were crossed with high, average and low averages of mean corneal power values to generate a 3x3 matrix of paired values. These values were used to generate a selection of a toric intraocular lens for manufacturers approved in USA or/and Europe. Using values of residual astigmatism computed by each toric calculator, a toricity ratio was generated for each pair of axial length and mean corneal power corresponding to each manufacturer. These values were compared to values published by the manufacturers and those predicted in the literature.
Our algorithm helped distinguish the manufacturers using a constant toricity ratio from those using a variable one. Those using a constant ratio were using around 1.45; while those using a variable ratio ranged from 1.3 to 2.3. These variable ratio results are consistent with the calculation published in the literature and our theoretical framework and confirm in particular that as axial length and mean K increase so does the toricity ratio.
Our algorithms contribute to identifying manufacturers using a constant toricity, and the precise variation of toricity ratio used by other manufacturers. This technique will further improve our ability to select appropriate toric IOLs for our patients. The relevant methodologies have been integrated into our Universal IOL calculator.
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