[Value of a new non-contact biometer for intraocular crystalline lens power calculation]

One of cataract surgery's current imperatives involves refraction: the power of the lens implant must be calculated as accurately as possible. Here we present a new method of biometric ocular measurement using the partial optical consistency interferometer.

This investigation studied the axial length measurement of 100 eyes. Five measurements were taken with a classic echobiometric contact technique using the ultrasonic mode; 5 others were taken with the infrared noncontact technique (IOL Master, Zeiss Humphrey). The latter technique is based on interferometric biometry with optical consistency and measurements were taken with an infrared luminous ray. With extreme rapidity and no contact, the device provides a complete biometry, including axial length, keratometry, and anterior chamber depth. It includes a built-in computer.

Comparing the ultrasonic and infrared measurements emphasizes the precision and particularly the high reproducibility of the infrared method. The standard deviations of the samples were significantly lower for the 100 measurements. Its limitations depends on the type of cataract since success was not obtained for certain posterior subcapsular opacities.

This new method of performing a biometry with a partial consistency interferometer contributes a number of advantages: speed, its noninvasive nature with no contact, the high reproducibility of the exam, as well as precise measurements as shown by the difference in the standard deviations of the two methods.

Biometry using the optical consistency interferometer seems to be a reliable, reproducible, and precise technique that brings great precision for the calculation of the power of the intraocular implant in cataract surgery.