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Advanced IOL platform provides benefits for surgeons and patients www.eyeworld.org 2013 ASCRS•ASOA San Francisco Show Daily Supplement This Show Daily supplement is sponsored by Alcon. Advanced biometry for advanced lenses by Warren E. Hill, MD The Lenstar helps increase refractive accuracy for patients, especially those with advanced IOL options T Warren E. Hill, MD This precision "the Lenstar an makes excellent device for surgeons who are looking to optimize their outcomes for all patients, as well as expand their premium lens patient population. oday's cataract patients, and especially those with premium lenses, have learned to anticipate nothing short of excellent postoperative vision, and using the most advanced biometry preoperatively helps us achieve that goal for our patients. Accuracy in IOL power calculations requires precise measurements, including axial length, lens thickness and keratometry, to provide the best estimate of the effective lens position by advanced formulas. In my opinion, the Lenstar LS900 (Haag-Streit AG, Koeniz, Switzerland) goes beyond what we generally expect from a biometer. The autokeratometry feature is both precise and uniquely suited to the toric IOL; a total of five axial measurements (central corneal thickness, aqueous depth, anterior chamber depth, lens thickness, and axial length) are by optical biometry. Every aspect of every measurement process is open to physician inspection, validation, and correction. K readings The Lenstar LS900 uses dual-zone keratometry, with two concentric rings of 1.65 and 2.30 mm. The 16 measurement points in each ring comprise a total of 32 measurement points. Each displayed K reading is a composite of four measurements, representing 128 measurement points. Performing five scans is recommended, which generates a total of 640 individual measurements per eye. Because the greatest distance that any measurement can be from a principal meridian is only 11 degrees, the K readings are uniquely suited for identifying the steep and flat meridians and the power difference between them, a requirement of the AcrySof toric IOL calculator (Alcon, Fort Worth, Texas). The K measurements can also be used with the ASCRS online post-keratorefractive surgery IOL power calculator. Comparatively, the IOLMaster (Carl Zeiss Meditec, Dublin, Calif.) measures only three points above and below the horizontal at 60 degrees, 120 degrees, and 180 degrees. With the Lenstar, each button push generates four displayed images, and if any displayed measurement point is not well formed, it's an indication the information in that quadrant may not be accurate. " This supplement was produced by EyeWorld and sponsored by Alcon. The doctors featured in this supplement received compensation from Alcon for their contributions to this supplement. Copyright 2013 ASCRS Ophthalmic Corporation. All rights reserved. The views expressed here do not necessarily reflect those of the editor, editorial board, or the publisher, and in no way imply endorsement by EyeWorld or ASCRS. The Lenstar provides the key biometry readings. Source: Haag-Streit (This is fairly common with moderate dry eye patients.) Users can easily repeat measurements until the quality is sufficient. In this way, there are far fewer keratometric surprises than might be seen by simply looking at numbers with no other information. We recently reported that the use of the dual-zone keratometry feature of the Lenstar in toric IOLs was equivalent to manual Ks.1 We also proposed validation criteria, with the proposed values for the standard deviation to achieve superior refractive results at 0.25 D or less for the K readings and 3.5 degrees or less for the axis. The repeatability of this biometer is unsurpassed. What has impressed me is that working with the combination of the Lenstar and advanced formulas like Haigis, Holladay 2, and Olsen, our outcomes are now tighter. It's the first automated biometer with keratometry accurate enough for me to trust it completely for my toric lens calculations. Precise axial length and lens thickness The company notes its optical coherence technology uses a superluminescent diode as a light source to allow axial length measurements even through dense cataracts. Axial measurements include the anterior and posterior cornea, aqueous depth, anterior chamber depth, lens thickness, and the full length of the eye. The device segments the eye into three areas—cornea and aqueous, lens, and posterior segment— and combines the data from those three segments to produce an overall axial length. In addition, the measurements are displayed in the familiar immersion A-scan format, making it easy to identify the locations of basic structures. Additionally, incorporating a measured lens thickness into the Holladay 2 formula increases refractive accuracy. A measured lens thickness is an important component of the Olsen formula as well. Having both the continued on page 2 Please refer to page 8 for important safety information about the Alcon products described in this supplement.