Eyeworld Daily News

12 | EYEWORLD DAILY NEWS | JULY 25, 2021 ASCRS ANNUAL MEETING DAILY NEWS criteria are met: 1) Regular bow- tie astigmatism within the central 3-mm zone. 2) Difference in corneal astigmatism magnitude between IOLMaster (Carl Zeiss Meditec) and LENSTAR (Haag- Streit) less than or equal to 0.75 D. 3) Difference in astigmatism meridian between IOLMaster and LENSTAR less than or equal to 15 degrees. There are a number of new options to address the issue of suboptimal accuracy, Dr. Koch continued, mentioning the AcuFocus IC-8, Morcher Xtra- focus sulcus IOL, RxSight Light Adjustable Lens, Perfect Lens, and Clerio. These remain challenging eyes, but the options for optimal outcomes are growing, Dr. Koch concluded. During the session, Li Wang, MD, PhD, spoke about the com- plex situations of long and short eyes. Some of the challenges with short eyes, she said, include poor refractive outcomes. These eyes may have variable anatomy, and ELP estimation is critical. Addi- tionally, there may be IOL shifts postoperatively. She noted a study evaluating seven formulas in short eyes, with a range of accuracy from 62.8– 77.9%. There was no statistically significant difference between formulas. A challenge in long eyes is that traditional formulas tend to select IOLs of insufficient power, which leaves patients with postop hyperopia. But she said the good news is that results are getting better. Dr. Wang added that accuracy can be improved with segmented axial length. This helps with less myopic outcomes in short eyes and less hyperopic outcomes in long eyes. She said that use of OCT may improve ELP prediction, but there are no prospective studies yet. In her practice, Dr. Wang noted that preferred formulas for short eyes include the Holladay 1, Barrett, and Hill-RBF 3.0. The Holladay 2 and Olsen formulas may also be used in challenging cases, she added. For long eyes, Dr. Wang suggested the WK axial length ad- justment with Holladay 1, Barrett, and Hill-RBF 3.0 formulas. Editors' note: Dr. Wang has finan- cial interests with Alcon and Carl Zeiss Meditec. Dr. Koch has finan- cial interests with Alcon, Johnson & Johnson Vision, Carl Zeiss Meditec, Perfect Lens, CAPSULaser, and Vivior. Surgeons present on IOL calculations D uring a session on IOL cal- culations, Douglas Koch, MD, shared some things to consider in complex situations post-LASIK. First, he said that "we still need to do better." The primary sources of error in standard IOL calculations are effective lens po- sition (ELP), the cornea (anterior and posterior), and refraction. All of these issues are magnified with post-refractive eyes, Dr. Koch said. ELP is a problem for formulas that use corneal power to predict or calculate the ELP because corneal power has been modified. When considering the cornea, there is variability in the central power of the anterior cornea in post-re- fractive patients, and there is measurement uncertainty for the posterior cornea. Additionally, there are soft endpoints for refrac- tion in these eyes. Another major point to consider, Dr. Koch said, is that measuring the posterior corneal power has not provided the bene- fit we had hoped for yet. Intraoperative aberrometry can be helpful in many practices, but he also mentioned data from his practice using ORA (Alcon) where the data was no better than preoperative calculations. Dr. Koch noted that you shouldn't panic or celebrate on the first day postoperatively. Post-LASIK corneas can flatten. He noted slow healing of up to 3 months in post-RK eyes. Toric IOLs can work well in post-refractive eyes. But he expounded on this, saying that toric IOLs are reasonable if three Dr. Wang discusses how to handle long and short eyes in a symposium on IOL calculations. Source: ASCRS

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