As the largest ophthalmology practice in Queensland, Terrace Eye Centre has a complete range of the latest diagnostic equipment available to help with patient care and optimise outcomes. Our latest purchase is the IOLMaster 700.
This update to the gold standard cataract biometer provides even greater precision in measurements of the eye allowing for the most accurate intraocular lens (IOL) selection and the ability to scan through even very dense cataracts with ease.
The new IOLMaster utilises swept source OCT instead of the previous partial coherence interferometry method. Traditional ocular biometry measures anterior corneal curvature, anterior chamber depth, corneal diameter and axial length to calculate the ideal intraocular lens power for each eye before cataract surgery. The IOLMaster 700 adds measurement of the posterior corneal curvature and lens thickness as well as providing an OCT scan of the macula in the same image. The more parameters measured, the more accurate the IOL prediction.
Astigmatism Management
The anterior surface of the cornea creates most of the astigmatism of the eye, but the posterior cornea also plays a role. In most people the posterior cornea has a small amount of against-the-rule astigmatism. However, the amount can vary significantly, and some people even have with-the-rule posterior astigmatism. In these patients, if you assume the average posterior corneal astigmatism then the calculated toric implant lens will be inaccurate. The IOLMaster 700 accurately measures the posterior corneal curvature which allows calculation of the actual total corneal power and therefore increases the accuracy of the toric lens selection, especially in those patients who lie outside the normal range.
The IOLMaster 700 also takes a reference image of the eye during scanning. This image perfectly correlates with the measured total corneal astigmatism and can be projected into the operating microscope eyepiece so that a toric IOL can be exactly aligned to the correct axis during surgery rather than relying on less accurate pre-operative ink marking of the eye.
These two advances, combined with careful auditing of refractive outcomes of cataract surgeries to calculate surgically induced astigmatism (SIA) as done at Terrace Eye Centre, is now the new standard of care for toric lens calculation. Eliminating astigmatism accurately is of course important even for patients who are not concerned about glasses use post-surgery and is vital for patients choosing multifocal lenses or monovision.
Better Accuracy
Until now the crystalline lens thickness has been very difficult to measure. Lens thickness is used in calculating the Effective Lens Position of an IOL, an important determinant of the required power of IOL to be implanted. Readers will be aware of lens effectivity: as the position of a lens moves its effective power changes. Where an intraocular lens sits in the capsular bag is a critical determinant of refractive outcome which can be better estimated by knowing the preoperative thickness of the patient’s natural lens. OCT scanning of the patient’s natural lens also shows unusual anatomy such as lens tilt or decentration which may affect post-operative lens positioning and the macula OCT allows checking of patient fixation during scanning and detection of macular pathology.
As well as the upgrades in scanning, the IOLMaster 700 also has significant improvements in software and workflow. The IOLMaster 700 takes 2000 scans per second, and both eyes can be scanned in 45 seconds which is great for patient comfort. It also now includes the latest Barrett and Holladay IOL calculators. Previously, biometry data from the IOLMaster and posterior curvature data from a Pentacam had to be manually copied into an online calculator if we wanted to take advantage of the latest formulas. With all measurements and formulae now in the same device the workflow is much smoother and the risk of data entry errors is eliminated.
By upgrading to the latest IOLMaster 700 Terrace Eye Centre remains at the forefront of technology for cataract patients. Whether patients want lens based surgery for a refractive glasses free outcome or don’t mind glasses and just want the best possible vision Terrace Eye Centre continues to offer the best care for all our patients.