Ultrasound biometry and intraocular lens power calculation: comparative study of the contact and immersion techniques

Purpose: To compare the ultrasound biometry measurements between immersion and contact techniques. Methods: The biometry was made in 60 eyes by the same examiner, using the contact and immersion techniques in each eye. Results: The lower mean axial length (23,16 mm) was found in the contact technique, and the greater (23,29) was found in the immersion technique, using the same probe. The lower mean standard deviation between recurrent measures in the same eye was found in the immersion technique, and the greater in the contact procedure, and was found statistically significant (p<0,001). The Pearson's coefficients demonstrated high correlation between the two techniques, in measuring the axial length and anterior chamber depth. Conclusion: The immersion technique have shown more accuracy and reproducibility, avoiding errors in intraocular lens power calculation, and encountering the visual expectations of the patient.