Marking method for toric IOL implantation yields alignment error

J Cataract Refract Surg. 2011;37(8):1394-1402.

A popular three-step ink marking procedure for toric pseudophakic and phakic IOL implantation produced notable alignment error, a study found.

“However, the error may be higher in individual cases as a result of problems with the ink marks,” the study authors said. “This error is especially relevant in cases in which higher cylinder power IOLs are implanted. Orienting the toric IOL with great accuracy is necessary in all patients to achieve the most optimum cylinder correction.”

The prospective cohort study included 40 eyes of 31 patients; 26 eyes were pseudophakic and 14 were phakic. Mean patient age was 58.8 years in the pseudophakic group and 40.1 years in the phakic group.

Patients underwent cataract extraction and implantation of an AcrySof toric SN60T3-T9 toric pseudophakic IOL (Alcon) or a toric phakic IOL (Artisan or Artiflex, Ophtec).

The three steps of toric IOL implantation were reference axis marking, alignment axis marking and IOL alignment. Investigators used vector analysis to calculate errors in toric IOL alignment.

Study results showed mean errors of 2.4° in reference axis marking, 3.3° in alignment axis marking and 2.6° in toric IOL alignment.

Combined, the three errors resulted in a mean total error in toric IOL alignment of 4.9°. Differences in mean error between pseudophakic IOL and phakic IOL alignment were statistically insignificant.

Vector analysis showed a mean angle of error of -2° for pseudophakic IOLs and 6° for phakic IOLs, the authors reported.