The IOLMaster was the first optical biometer; the IOLMaster 700 (Figure 1) now incorporates swept-source OCT technology, making it the first swept-source biometry device, claims manufacturer Carl Zeiss Meditec.1 The features of this device can help users to decrease refractive surprises and improve refractive outcomes, according to company literature.
Swept-source biometry provides a full-length OCT image of the eye, showing anatomic details in a longitudinal cut through the length of the organ. Depiction of this image allows identification of unusual features of ocular geometry such as crystalline lens tilt or decentration, which could contribute to suboptimal surgical outcomes if undetected. The OCT image also provides a fixation check: If the image shows the foveal pit, the user knows that the patient achieved proper fixation; if not, the patient can be educated to fixate better on the target.
The full-length OCT image of the IOLMaster 700 also displays measurement calipers so the user can visually verify what anatomic structures are being measured, rather than having to interpret which peak on an A-scan is the feature of interest. According to company literature, the swept-source device performs 2,000 scans per second. Anatomic measurements include the biometric parameters required for modern IOL power calculation formulas, including central corneal thickness, lens thickness, axial length, and anterior chamber depth.
SOFTWARE AND OTHER FEATURES
Software on the IOLMaster 700 includes the Haigis Suite, an all-in-one solution combining the Haigis IOL power calculation formula with the Haigis-L formula for eyes after laser refractive surgery and the new Haigis-T formula for toric IOL calculations. With the onboard toric calculator, there is no need to key in refractive data to IOL manufacturers' online calculators.
Although the device is new, it is compatible with earlier versions of the IOLMaster, so that the User Group of Laser Interference Biometry database can be used. The database contains lens constants for more than 270 IOLs based on data from more than 50,000 surgeries collected specifically for the IOLMaster, according to the company, and these data can be used to help refine refractive outcomes.
The device also offers what the company calls telecentric keratometry, which is a distance-independent approach that allows repeatable measurements even for restless patients. A multitouch screen gives users a means to employ gesture controls on the graphical user interface similar to those used on smartphones and tablets. Measurement tasks can be delegated because alignment functions make results largely independent of the user.
When a toric IOL is to be implanted, the IOLMaster 700 can operate as a part of the Zeiss Cataract Suite markerless, a platform that also includes the IOLMaster 500, Callisto eye, and OPMI Lumera family of microscopes (all devices by Carl Zeiss Meditec). For any eye with astigmatism, the biometry device can acquire a reference image taken at the same time as the keratometric measurement, and these data can be transferred to the Callisto Eye computer-assisted cataract surgery system.
During the surgical procedure, the reference image can be matched to the live microscope image of the OPMI Lumera. All relevant data are then displayed in the eyepiece of the surgical microscope, so that preoperative corneal marking and other procedures for toric IOL alignment are not needed. n
1. The new IOLMaster 700. Carl Zeiss website. http://www.zeiss.com/meditec/en_de/products---solutions/ophthalmology-optometry/cataract/diagnostics/optical-biometry/iolmaster-700.html#highlights. Accessed June 5, 2015.