To formulate an equation to estimate corneal spherical aberration using Orbscan (Bausch & Lomb Surgical, Rochester, NY, USA) parameters.

The study was carried out retrospectively. The participants were 76 eyes of 76 senile cataract patients with the mean age of 57.37 ± 17.63 years. Both Orbscan and KR-1W (Topcon Corp, Tokyo, Japan) were taken as preoperative examinations. Correlation analysis between various parameters from Orbscan and corneal spherical aberrations for a 6 mm pupil by KR-1W was performed. And multivariable linear regression was performed with the significantly correlated Orbscan parameters from the correlation analysis.

The mean corneal spherical aberration from KR-1W system was 0.25 ± 0.08 µm. As a result of the multivariable linear regression, we could generate following equations. If the Q -value was available, estimated corneal spherical aberration = 0.389 × Q -value + (0.022 × Axial power 3 mm) - 0.633 (R² = 0.436). If the Q -value was not available, estimated corneal spherical aberration = 0.184 × (Mean power 5 mm - Mean power 3 mm) + (0.02 × Axial power 3 mm) - 0.563 (R² = 0.429). By using the equations, 93.4-94.7% of subjects were in the error range of 0.10 µm.

Even when equipped with Orbscan only, an appropriate aspheric intraocular lens can be selected using the estimated corneal apherical aberration by the equations.