[IOL power determination using regression formula of lens location].
Postoperative lens location was expressed as a linear regression formula of axial length and corneal curvature. Using the formula, the IOL power of a convexplano, biconvex, and planoconvex lens was calculated by Ray Tracing Error Correction (RTEC). The calculated power of a convexplano lens coincides with Sanders, Retzlaff, Kraff (SRK) II in axial length less than 28 mm and corneal curvature between 7 to 9 mm. Varying regression coefficients changes lens power continuously and simulates the theoretical formulas SRK II and SRK. RTEC predicted that formula SRK II is valid only for a convexplano lens and needs correction in a biconvex or planconvex lens and in corneal curvature less than 7.0 mm. IOL power determination requires a learning process based on the postoperative refraction. The difference of learning between SRK and RTEC is also discussed.
Kashiwagi
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Kashiwagi Eye Clinic, Sakai-city, Japan.
D006801:Humans; D007910:Lenses, Intraocular; D009907:Optometry / Q000379:methods*; D011184:Postoperative Period; D012044:Regression Analysis