The technique functions over a wide range of refractive errors and is capable of measuring highly aberrated eyes.Īccording to literature from AMO WaveFront Sciences, LLC, the current version of the COAS is the world’s highest-resolution wavefront aberrometer. By subtracting the corneal refractive power from the total optical path difference or wavefront error, the unit is able to generate an internal optical path difference reflecting the optical quality and refractive state of the crystalline lens and internal ocular media. The Nidek-OPD Scan II provides information on corneal topography, wavefront measurements, autorefraction, keratometry, and pupillometry. In essence, the device produces a highly detailed retinoscopic map of the refractive state of the eye from numerous points on the cornea. The unit scans the retina with an infrared slit beam, and the reflected light is captured by an array of rotating photo detectors over a 360º area. The Nidek-OPD Scan II (Nidek, Inc., Fremont, CA) utilizes the principle of skiascopic phase difference to measure refractive error. A number of devices have been developed using various strategies to increase the sensitivity, validity, and range of wavefront measurements. As a result, surgeons came to appreciate the diagnostic value of aberrometry as well as its limitations. The proliferation of devices associated with wavefrontguided laser procedures allowed ophthalmologists to examine numerous eyes in association with various refractive treatments, IOLs, and naturally occurring pathology. The vast majority of aberrometers in use with laser systems employ the Shack- Hartmann principle. According to Alcon Laboratories, Inc., the advantage of the Tscherning method for wavefront-guided laser treatments is that it avoids inaccurate results from media opacities, which can produce false positives with a Shack-Hartmann device. In contrast, Tscherning aberrometers project a spot pattern of 168 points into the eye and analyze the image of the spot pattern on the retina. Shack-Hartmann aberrometers send a single light beam into the eye and then analyze the outgoing light bundle. The Allegro Analyzer, part of the WaveLight Allegretto line (Alcon Laboratories, Inc.), uses the Tscherning principle to obtain wavefront data and expresses the results in Zernike polynomials. The LADARWave, although no longer commercially available, is still used by many clinicians for diagnostic evaluations. The WaveScan currently uses Fourier algorithms to analyze data and improve precision. These aberrometers are based on Shack- Hartmann principles and use Zernike analysis to express the results in both mathematical and graphic terms. The WaveScan Wavefront System was approved in 2003 for use with the Visx Star S4 excimer laser (both products from Abbott Medical Optics Inc., Santa Ana, CA). In the United States, the LADARWave aberrometer (built by Carl Zeiss Meditec, Inc., Dublin, CA) was approved for use in 2002 with the LADARVision excimer laser (both products from Alcon Laboratories, Inc., Fort Worth, TX). Theo Seiler, MD, PhD, performed the first such procedure in the world using the WaveLight platform (WaveLight Laser Technologie AG, Erlangen, Germany) in 1999. The widespread introduction of aberrometers into clinical ophthalmology occurred primarily in association with the development and approval of wavefront-guided laser treatments. Numerous other methodologies and applications have since arisen. ![]() The original aberrometers were based on the Shack-Hartmann principle, a technique developed by Johannes Hartmann in 1900 and modified by Shack and Platt in the late 1960s. Aberrometry was introduced to the vision sciences in the mid-1990s, and the first commercially available clinical aberrometer was the COAS (Complete Ophthalmic Analysis System) from AMO WaveFront Sciences, LLC (Albuquerque, NM), released in 2000. This technique has been used for years, particularly in astronomy, to develop accurate optical systems. How to Create a Patient-Satisfaction SurveyĪberrometry is the measurement of the imperfections in an optical system. Measuring What Matters: Patients’ Satisfaction and Referrals Knowing Your Practice Is No Longer Optional Sidebar: A PREVIOUSLY UNDERRECOGNIZED BUT IMPORTANT SIDE EFFECTĪssessing Refractive Change After Excimer Laser Surgeryĭetermining Ocular Fixation for Centering IOLs With Purkinje ImagesĬomplex Case Management: High Astigmatism After PKP
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