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ORange® Technology
ORange is the first ever intraoperative wavefront aberrometer. It is comprised of an optical head that is attached directly to the surgical microscope and connected to the ORange processor and touch-screen monitor. ORange is used during cataract surgery to accurately measure the refractive value of the eye. At any point during surgery the surgeon captures a wavefront of the patient’s eye. The ORange processor then analyzes the captured data to calculate the refractive value of the eye.
When a wavefront is captured, a very narrow beam of light is directed into the patient’s eye, and is reflected off the retina. As the reflected light passes back through the optical elements of the eye, it produces an aberrated wavefront. Using a technology known as Talbot-Moiré interferometry, ORange analyzes the wavefront through a proprietary process to produce the refractive value.
What’s Talbot-Moiré and What Makes it Different from Other Wavefront Measurement Methods?
Wavefront technologies, such as Hartmann-Shack use optical and mathematical principles to capture and analyze a wavefront. Wavefront analysis using these technologies is in common use today in refractive surgery. However, these technologies do not lend themselves to use in cataract surgery, as by their optical design they are too large to incorporate into the surgical field. More importantly, these technologies have a limited dynamic range, typically -10D to +8D, while the typical cataract patient’s eye averages +13D, but can be as high as +20D, in it’s aphakic state.
ORange employs a novel form of wavefront analysis, known as Talbot-Moire’ interferometry. Whereas in Hartmann-Shack wavefront sensing the wavefront passes through a lenslet array and the resultant pattern of spots is analyzed, in Talbot-Moire’, the wavefront passes through a pair of gratings set at a specific distance from and angle offset to each other. The diffraction of the wavefront as it passes through the grating pair produces a fringe pattern, which is analyzed using proprietary algorithms. Aberrations in the wavefront cause distortions in the fringe pattern which, when analyzed, are translated into the refractive value of the aberrated eye.
The nature of the optical design of a Talbot-Moire’ system enables two very important characteristics featured in the ORange system. First, it can be made very compact and lightweight, such that it can be attached directly to the underside of the surgical microscope without interfering with critical working space or the optical path of the scope itself. Second, the Talbot-Moiré interferometry method is capable of a dynamic range of -20 D to +20 D, with no degradation of resolution of the fringe pattern. The ORange system is configured to have a dynamic range of -5 D to +20 D, enabling its use at any point in the surgery - phakic, aphakic, or pseudophakic – on almost any eye likely to be encountered.