Decentration and tilt of a single-piece aspheric intraocular lens compared with the lens position in young phakic eyes.

PURPOSE

To compare the tilt and decentration of a single-piece aspheric intraocular lens (IOL) and the position of the natural crystalline lens in young individuals.

SETTING

Department of Ophthalmology, Knappschafts Hospital, Sulzbach, Germany.

METHODS

This prospective noncomparative single-center study included volunteers younger than 40 years with no ocular abnormalities (crystalline lens group) and patients older than age 62 who had uneventful cataract surgery and Tecnis ZCB00 IOL implantation (IOL group). All eyes were examined with the OPD-Scan II; spherical aberration, vertical coma Z(3,-1), and horizontal coma Z(3,1) were analyzed with a 5.0 mm pupil. Lens tilt and decentration were studied with a new Purkinje meter.

RESULTS

The crystalline lens group and IOL group comprised 20 subjects (40 eyes) each. Both groups showed compensation for corneal spherical aberration and neutralization of horizontal corneal coma. All lenses were tilted upward (mean 2.2 degrees, crystalline lens; 2.5 degrees, IOL) and to the temporal side (mean 3.1 degrees, crystalline lens; 2.6 degrees, IOL). The crystalline lenses were decentered downward (mean 0.16 mm) and to the temporal side (mean 0.07 mm). The IOL was displaced to the nasal side of the pupil (mean 0.06 mm) with almost no vertical mean decentration (0.02 mm upward).

CONCLUSIONS

The aspheric IOL and young crystalline lens compensated for mean corneal spherical aberration, resulting in low total spherical aberration. The position of the IOLs showed minimal decentration and tilt and was mirror symmetrical, comparable to the position of the crystalline lens in young individuals. The slight malpositioning partially compensated for corneal horizontal coma.