High Precision Biometry of Pseudophakic Eyes Using Partial Coherence Interferometry

Purpose: To investigate the applicability of the scanning version of dual-beam partial coherence interferometry (PCI) for measuring the anterior segment and axial length of pseudophakic eyes in a clinical setting and to determine the achievable precision with this biometry technique.

Setting: Department of Ophthalmology, Vienna General Hospital, and Institute of Medical Physics, University of Vienna, Austria.

Methods: Partial coherence interferometry was performed in 39 pseudophakic eyes of 39 patients after implantation of a foldable acrylic intraocular lens (IOL).

Results: Effective lens position (ELP), IOL thickness and lens-capsule distance (LCD) were determined with a precision of 2 to 3 microns; corneal thickness and axial eye length, with a precision of 0.8 and 5.0 microns, respectively. The mean ELP of the IOL was 4.093 mm +/- 0.290 (SD). In 7 eyes (18%), a positive LCD of 68 +/- 40 microns was detected with PCI. Mean corneal thickness was 526.4 +/- 31.5 microns; mean IOL thickness, 791.5 +/- 40.2 microns; and mean axial length, 23.388 +/- 0.824 mm.

Conclusion: The scanning version of PCI enables high precision (< or = 5 microns) and high resolution (approximately 12 microns) biometry of pseudophakic eyes that is better than conventional ultrasound by a factor of more than 20. For the first time, positive LCD, a possible risk factor for posterior capsule opacification, could be detected and quantified. Furthermore, this technique offers a high degree of comfort for the patient since it is a noncontact method with no need for local anesthesia or pupil dilation and has a reduced risk of corneal infection.