[Comparison of contact and immersion techniques of ultrasound biometry in terms of target postoperative refraction]

The success of cataract surgery in terms of the postoperative refractive result depends on the calculation of optimal intraocular lens (IOL) power. The accuracy of preoperative measurements (keratometry, biometry) is of a great importance due to the increasing patients' demands on final refractive results. The purpose of this study was to compare the accuracy of contact and immersion techniques of A - scan ultrasound biometry in terms of target postoperative refraction while using the SRK/T formula. The accuracy of the applied biometric techniques was compared by means of the postoperative spherical equivalent (SE). The prospective longitudinal study included 111 non-paired eyes, and the preoperative biometry was performed by means of an OcuScan ultrasound machine (Alcon).The contact technique was used in 48 eyes whereas the immersion technique was employed in 63 eyes.The mean SE in the group measured by the contact technique was -0.13 D, compared to 0.25 D in the group with the applied immersion technique. No statistically significant difference was found in postoperative spherical equivalents while using both biometric techniques (p > 0.1). In this study the choice of a biometric technique had therefore no influence on the predicted postoperative refraction. The results have indicated that the biometric techniques (contact and immersion) are interchangeable in terms of postoperative refractive results.