To investigate the accuracy of measuring ultrasonic axial lengths using A-scan (Ocuscan®, Alcon, USA) on opaque intraocular lenses after hydrophilic lens (ACRL-160®, Ophthalmed, USA) implantation.

We measured axial length through ultrasonic biometry prior to intraocular lens exchange. Twelve eyes of 14 patients who had intraocular lens opacity following hydrophilic acryl lens implantation were examined in a clinical study. We compared pre-cataract operative axial lengths to pre-IOL exchange axial lengths. The pre-IOL exchange axial lengths were measured in aphakic and pseudophakic modes. In the pseudophakic mode, the ultrasound velocity through an IOL was set at a rate ranging between 1,500 m/sec to 2,200 m/sec.

The pre-IOL exchange axial lengths in the pseudophakic mode at the rate of 1,600 m/sec in lens velocity were the closest to pre-cataract operative values ( p =0.88).

When pre-cataract operative axial length is known with a hydrophilic acrylic intraocular lens, previous values may be used for IOL exchange of an opacity patient. If not, however, the closest values to pre-cataract operative axial lengths may be obtained by setting the velocity in the pseudophakic mode to a lens velocity rate of 1,600 m/sec.