In vivo IOL power determination possible

July 23, 2007

Approximate in vivo intraocular lens (IOL) power can be determined using Scheimpflug imaging and could be applied in cases of unexplained postoperative refractive error.

Approximate in vivo intraocular lens (IOL) power can be determined using Scheimpflug imaging and could be applied in cases of unexplained postoperative refractive error, according to the results of a study published in the June issue of the Journal of Cataract and Refractive Surgery.

Stephen Turner and colleagues from the King's College Hospital Ophthalmology Department, London, UK assessed the feasibility of determining IOL power by measurement of the central optic thickness using clinically available Scheimpflug imaging. A total of 67 eyes were assessed one month after phacoemulsification with in-the-bag implantation of AcrySof MA60AC IOLs (Alcon). The correlation between IOL thickness measurement and IOL power was calculated and the repeatability of central optic thickness measurement was determined by 10 successive scans of four patients.

The coefficient of variability was 1.4% and the measured lens thickness was highly correlated with lens power (r2=0.94, p<0.001). Over the measured range, 95% confidence intervals varied between ±0.83 D and ±0.92 D.

The authors concluded that central IOL thickness measurements with the Scheimpflug camera are repeatable and closely correlate with the known IOL power, making in vivo IOL power determination a feasible option, especially in cases of unexplained postoperative refractive error.