Background: To examine the influence of posterior corneal astigmatism on postoperative refractive astigmatism in\npseudophakic eyes after cataract surgery.\nMethods: The study enrolled 64 pseudophakic eyes of 50 patients (71.8 �± 9.9 years old, mean �± standard deviation)\nwho had undergone phacoemulsification with non-toric IOL implantation. Refractive astigmatism was measured\nusing an auto ref-keratometer with a 0.01- diopter (D) scale. Two types of corneal astigmatism were calculated\nusing anterior segment optical coherence tomography; keratometric and total corneal astigmatism. Keratometric\nastigmatism was obtained based on anterior corneal curvature alone and total corneal astigmatism was calculated\nusing both anterior and posterior corneal curvatures. The difference between refractive and corneal astigmatism\nwas computed as the vector difference using 1) refractive and keratometric astigmatism and 2) refractive and total\ncorneal astigmatism.\nResults: The mean refractive, keratometric, and total corneal astigmatism was 0.92 �± 0.48 D, 0.87 �± 0.44 D,\nand 0.94 �± 0.46 D, respectively. The difference between refractive and keratometric astigmatism (0.70 �± 0.40 D, mean\nvector of 0.30 D axis 164�°) was significantly larger than the difference between refractive and total corneal astigmatism\n(0.63 �± 0.38 D, mean vector of 0.12 D axis 137�°) (P = .019).\nConclusions: The difference between refractive and total corneal astigmatism, calculated using both anterior\nand posterior corneal curvatures, was significantly smaller than the difference between refractive and keratometric\nastigmatism using anterior corneal astigmatism alone, implying that the latter overestimates the true postoperative\nrefractive astigmatism and can cause cylindrical inaccuracy after cataract surgery.
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