PARTIAL COHERENCE INTERFEROMETRY - A NOVEL-APPROACH TO BIOMETRY IN CATARACT-SURGERY

PURPOSE: To compare biometry performed by an enhanced version of dual beam partial coherence interferometry and applanation ultrasound in a prospective study of 85 cataract eyes to improve refractive outcome of cataract surgery due to a more accurate calculation of intraocular le ns power. METHODS: The SRK IT formula using ultrasound biometry data w as employed. Three months after surgery, partial coherence interferome try biometry was repeated and refractive outcome was determined. Preop erative partial coherence interferometry biometry data were used to de termine the refractive power of the intraocular lenses retrospectively and to calculate the possible refractive outcome.RESULTS: Precision o f partial coherence interferometry biometry was more than 10 times bet ter than that of ultrasound. Therefore, the possible mean absolute err or for postoperative refraction achieved with partial coherence interf erometry biometry was 0.49 diopters (compared with 0.67 diopters with ultrasound biometry), resulting in an improvement of 27%. Axial eye le ngth measured with the two techniques differed by a mean of 460 mu m T he difference in lens thickness measured with partial coherence interf erometry and ultrasound significantly correlated with cataract grade. A mean shortening of 120 mu m of axial eye length following cataract s urgery was also detected by partial coherence interferometry, CONCLUSI ONS: The enhanced version of partial coherence interferometry offers b iometry with unprecedented precision (<10 mu m) and resolution (simila r to 12 mu m), therefore improving the refractive outcome in cataract surgery, This noninvasive technique provides a high degree of comfort for the patient, with no need for local anesthesia or pupil dilation a nd minimized risk of corneal infection, (Am J Ophthalmol 1998;126:524- 534 (C) 1998 by Elsevier Science Inc. All rights reserved.).