[Comparision of two new optical biometry devices with an ultrasonic immersion biometer].

PURPOSE

To compare two new optical biometry devices with an ultrasonic immersion biometer.

SETTING

Oftaprof Clinic, Iasi, Romania.

METHODS

In this prospective comparative observational study were included 420 eyes that underwent cataract extraction. Axial length measurements were performed using a Allegro BioGraph biometer, which uses optical low-coherence reflectometry (OLCR), an IOLMaster 500 biometer, which uses partial coherence interferometry (PCI) and an OcuScan ultrasonic biometer. The measurement duration and the number of eyes in which the measurements with each device could be performed were compared. Intraocular lens (IOL) power calculation was performed and the IOL prediction error was calculated for each eye four weeks postoperatively.

RESULTS

The mean difference in axial length measurements was 0.02 mm +/- 0.04 (SD) between the new PCI and the OLCR device, 0.14 +/- 0.13 (SD) mm between the ultrasonic biometer and the new PCI device and 0.18 +/- 0.09 (SD) mm between the ultrasonic biometer and the OLCR device (P=.52, P=.001 and P<.001, respectively). Measurements with the OLCR device took significantly longer than with the ultrasonic device (mean difference 88 +/- 27 seconds), and measurements with the ultrasonic device took significantly longer than with the new PCI device (mean difference 188 +/- 46 seconds) (P<.001). The mean absolute error in IOL power prediction was 0.49 D +/- 0.29 (SD) with the OLCR device and 0.52 +/- 0.33 (SD) D with the PCI unit and 0.77 +/- 0.65 (SD) with the ultrasonic biometer. The measurements could be performed in 420 eyes (100%) with the ultrasonic biometer, in 152 eyes (36.2%) with the OLCR device and in 151 eyes (35,9%) with the new PCI device.

CONCLUSIONS

Measurements of the axial length were comparable between OLCR device and the new PCI device. There was a good correlation between the measurements with optical devices and the ultrasonic biometer. Measurements with the OLCR device took the longest to perform. Implant power calculation were comparable between the two optical devices. The ultrasonic biometry remains a very useful tool in cases with severe lens opacification which are extremely frequent in our service.