Effectiveness of intraocular lens calculation in high ametropia.

The error in prediction of emmetropic intraocular lens power or postoperative refractive error after lens implantation was analyzed in three groups of eyes after posterior chamber lens implantation. Regression line calculation with the SRK equation or with a group-specific regression was compared with theoretical calculations in unselected, long myopic and short hyperopic eyes. The cut-off length was below 22.0 mm for the short eyes and above 25.9 mm for the long eyes. In the unselected and hyperopic group, there was only a small difference in mean error and error variance when the three calculation methods were compared. In the high myopic group, the range of error increased in all methods. The worst results were obtained with the standard SRK equation because the slope of the regression line in myopic eyes differs from the classical regression line calculated on an average population of implants. Lens calculation in high myopic eyes should therefore be performed with a specific regression line or by theoretical calculation.