Cataract surgery in the myope: What you should know

Abstract

Improvements in technology have led to an increased safety profile in cataract surgery. Accordingly, in recent decades there has been an increasing clinical focus on providing improved refractive outcomes.

Initially using manual keratometers and ultrasound biometry, advances in intraocular lens (IOL) formulae lead to increased precision and accuracy of IOL calculations. This manifested in the form of decreased requirement for spectacle correction, usually at a distance target.

Later, optical biometry supplanted ultrasound as a more accurate method for the measurement of axial length and anterior chamber depth; it may also be useful in the measurement of lens thickness and white-to-white limbal distance. Newer biometers have built-in topographers with accurate keratometry.

It is beneficial to have an experienced ultrasonographer to perform testing in myopes, but it should be noted that posterior staphyloma can cause issues for the most experienced technicians. Some of the newer optical biometers capture a small OCT image at the time of testing to be used to test for foveal alignment, which is especially important in staphylomatous eyes.

More accurate testing, combined with newer-generation IOL formulae, has resulted in further improvement in the accuracy and precision of IOL calculation and increased spectacle independence for patients, commonly at distance. Moreover, newer intraocular lenses including multifocal and trifocal IOLs have increased the probability of spectacle independence at both distance and near. Furthermore, extended range of vision IOLs can provide distance and intermediate vision, with less dysphotopsia than current multifocal lenses.

Despite these advances, there are patient populations in which special attention is required to achieve improved refractive outcomes. Patients with increased axial length (myopes) have suffered from systematic errors in IOL calculation. Initially, modifications to previously developed IOL formulae were developed to compensate for this. The Wang-Koch correction (including its newer-generation correction) to various formulae would be an example of this.

Currently, the newest generation of IOL formulae perform better, without correction, than the previous generation of formulae, with or without correction.