Intraoperative optical refractive biometry for intraocular lens power estimation without axial length and keratometry measurements

Abstract

A new model for IOL power calculation was derived based on an optical refractive methodology that breaks away from the conventional art introduced by Fyodorov in the 1960s. A purely refractive algorithm is used to predict the power of the IOL at the time of surgery without the need for axial length and keratometry measurements. This method bypasses some limitations of conventional biometry and shows promise in the post-refractive cataract cases.

Accuracy of Scheimpflug Holladay Equivalent Keratometry Readings after Corneal Refractive Surgery in the Absence of Clinical History

“…Several authors have proposed formulas to adjust the calculated target IOL power. The nomogram-based adjustment of Feiz et al [9] and the regression formula of Masket and Masket [10], for example, require prerefractive surgery corneal power data, whereas the intraoperative aphakic refraction method [11] and the double-keratometry (dK) method of Aramberri [12] do not.…”

Intraocular lens calculation by intraoperative autorefraction in myopic eyes

“…Intraoperative autorefraction is a reliable alternative to standard biometry in myopic eyes. A table for clinical use is provided.Most common methods of intraocular lens (IOL) calculation in cataract and refractive lens exchange (RLE) use anatomic parameters (axial length, corneal curvature, and IOL position) to predict IOL power [1, 2], but the elongated configuration of the posterior pole in highly myopic eyes may affect precision [3].An alternative method is represented by intraoperative autorefraction, performed by a hand-held instrument after crystalline lens removal [4][5][6], by which aphakic spherical equivalent (SE) can be directly converted into IOL power. Axial length and corneal curvature are not required, and this can be extremely useful in surgically altered corneas [5].…”

“…An alternative method is represented by intraoperative autorefraction, performed by a hand-held instrument after crystalline lens removal [4][5][6], by which aphakic spherical equivalent (SE) can be directly converted into IOL power. Axial length and corneal curvature are not required, and this can be extremely useful in surgically altered corneas [5].…”

“…Axial length and corneal curvature are not required, and this can be extremely useful in surgically altered corneas [5].…”

“…Two separate attempts to provide a formula for IOL calculation by intraoperative autorefraction have resulted in two different regression lines because of the different populations studied: the first evaluated 38 low myopic and emmetropic eyes [5], and the second 37 highly myopic eyes [6].…”