Anterior segment changes during accommodation in eyes with a monofocal intraocular lens: High-frequency ultrasound study

Purpose

To analyze anterior segment structure changes during accommodative stimuli after monofocal intraocular lens (IOL) implantation using 2 ultrasound biomicroscopy (UBM) systems.

Setting

Department of Ophthalmology, University of Verona, Verona, Italy.

Methods

Twenty-six eyes (23 patients) with 1 of 4 monofocal IOL types were studied. Five to 9 months postoperatively, the patients were examined by high-frequency UBM using the HiScan system (Optikon 2000 SpA) and UBM 840 system (Carl Zeiss Meditec). Anterior chamber depth (ACD), iris–zonule distance, anterior chamber angle (ACA), scleral–ciliary process angle, and iris–ciliary process angle were measured using both systems. The iris–ciliary process distance and scleral spur perpendicular–sulcus distance were measured with the UBM 840 system and the sulcus–sulcus distance and capsular bag–IOL position with respect to ciliary process apex, with the HiScan system. Two experienced examiners performed all measurements.

Results

All parameters except the horizontal iris–ciliary process distance and vertical ACA measured by the UBM 840 system and horizontal ACA by the HiScan system showed significant variation during accommodation. An anterior shift of the IOL–capsular bag ciliary processes–sulcus–zonular iris complex was observed. A simultaneous centripetal shift of ciliary bodies and processes, shown by a reduction in sulcus and capsular bag diameter, was also observed.

Conclusion

Anterior segment structures demonstrated accommodative movement on UBM after implantation of standard monofocal IOLs.