Frown incision for minimizing induced astigmatism after small incision cataract surgery with rigid optic intraocular lens implantation

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A new technique, the frown incision, was developed and a series of 62 eyes with 6 mm and 7 mm incisions for intercapsular phacoemulsification and implantation of a 6 mm or 7 mm one-piece biconvex poly(methyl methacrylate) (PMMA) posterior chamber intraocular lens with single horizontal mattress suture closure was prospectively evaluated for induced astigmatism. A prior series of 34 eyes that had a similar procedure with 6 mm and 7 mm standard scleral pocket incisions closed with an infinity suture or a horizontal running single-knotted suture containing three loops was retrospectively reviewed and compared with the frown incision trial. Vector analysis calculations of diopters (D) of mean induced keratometric astigmatism for the frown incision versus the scleral pocket incision groups were 0.80 D versus 1.19 D (P = .0263) at one day; 0.74 D versus 1.03 D (P = .0547) at one week; 0.71 D versus 1.07 D (P = .0057) at four weeks; 0.84 D versus 1.15 D (P = .0072) at six months; 0.82 D versus 1.30 D (P = .0144) at one year. The frown incision group consistently had a lower standard deviation from the mean induced astigmatism than the scleral pocket incision group. Using regression analysis and Pearson product-moment correlations, the frown incision group had a higher degree of linear dependence of postoperative astigmatism on preoperative astigmatism. Recent modifications of the frown incision have reduced its chord length for insertion of any given optic size. Results suggest that the frown incision may provide many of the benefits of a 4 mm scleral pocket incision for flexible optic lenses.