Eyeworld

59 EW FEATURE January 2017 • All about IOL calculations Location of standard deviation of corneal radii on LENSTAR printout Source (all): Jack Holladay, MD EyeWorld Monthly Pulse EyeWorld Monthly Pulse is a reader survey on trends and patterns for the practicing ophthalmologist. Each month we send an online survey covering different topics so our readers can see how they compare to our survey. If you would like to join the hundreds of physicians who take a minute a month to share their views, please send us an email and we will add your name. Email carly@eyeworld.org and put "EW Pulse" in the subject line. Poll size: 231 corneal astigmatism, systematic IOL tilt/decentration, and ATR wound fade with time," Dr. Holladay said. Dr. Rubenstein noted that the posterior cornea has an important role in overall corneal power. "For patients who have with- the-rule astigmatism, the posterior cornea adds about 0.5 D of effect," Dr. Rubenstein said. "Therefore, for patients who have with-the-rule astigmatism, you want to decrease the power of a toric lens implant by approximately 0.5 D. For patients with against-the-rule astigmatism, increase the power of the toric IOL by approximately 0.3 D." The approach requires that patients have approximately 1.7 D of with-the-rule astigmatism before a toric lens is used and as little as 0.7 D of against-the-rule astigmatism in order to qualify for a toric lens that is placed against-the-rule. Incision use Dr. Holladay limits his use of limbal relaxing incisions (LRIs) to address- ing very small amounts of preopera- tive astigmatism. "Toric IOLs are much more pre- cise due to the variability in wound healing with LRIs," Dr. Holladay said. "With femtosecond lasers, the variability of the surgery has been eliminated, but the results are not significantly improved due to the variability in healing." Dr. Rubenstein also generally prefers toric lens implants over peripheral corneal relaxing incisions for most patients. However, cases where he would use such incisions include patients with a very low degree of astigmatism—less than 1 D—who receive one nasal relaxing incision or two short paired inci- sions to reduce astigmatism, which avoids potential overcorrection with a toric IOL. "If a patient has a very large degree of astigmatism, I sometimes combine a toric lens implant with a relaxing incision to provide extra effect," Dr. Rubenstein said. "If the patient cannot afford to pay for a toric lens implant, I may correct the astigmatism with a peripheral corne- al relaxing incision." Additionally, Dr. Rubenstein of- ten adds peripheral corneal relaxing incisions when performing femto- second laser-assisted cataract surgery "to add a slight extra effect that helps to fine tune my results." Dr. Rubenstein bases such de- cisions on a modified Nichamin or Donnenfeld nomogram. EW References 1. Behndig A, et al. Aiming for emmetropia after cataract surgery: Swedish National Cat- aract Register study. J Cataract Refract Surg. 2012;38:1181–6. 2. Maeda N, et al. Disparity of keratome- try-style readings and corneal power within the pupil after refractive surgery for myopia. Cornea. 1997;16:517–524. Editors' note: Dr. Holladay has finan- cial interests with AcuFocus (Irvine, California), Alcon (Fort Worth, Texas), Abbott Medical Optics (Abbott Park, Illinois), Calhoun Vision (Pasadena, California), and Carl Zeiss Meditec. Dr. Klyce has financial interests with NIDEK (Fremont, California). Drs. Tipperman and Rubenstein have financial interests with Alcon. Contact information Holladay: holladay@docholladay.com Klyce: sklyce@klyce.com Rubenstein: Jonathan_Rubenstein@rush.edu Tipperman: rtipperman@mindspring.com

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