Eyeworld

R AUGUST 2019 | EYEWORLD | 33 Contact information Holladay: holladay@docholladay.com Khandelwal: Sumitra.Khandelwal@bcm.edu that does not like to be myopic after surgery," Dr. Khandelwal said. Post-refractive surgery eyes and patients with nanophthalmos can be difficult to calculate due to poor effective lens position predictions, resulting from unusual measurements, Dr. Holl- aday said. In these cases, he emphasized corneal topography and tomography with repeated measurements. However, he noted, the vari- ability in outcomes is still greater than that of a normal patient. As for final pearls for IOL calculations for those who are still relatively new in practice, Dr. Holladay reiterated implementing the quality checks on axial length and keratometry, as he already described, and of personalizing your lens constant. "It can improve the percentage of cases within ±0.50 D by 5%," Dr. Holladay said. Dr. Khandelwal recommended picking two easy-to-access formulas and repeating them with the same pattern for 30–40 cases. Then look back at these outcomes to determine your surgeon factor and see which formula works best for you. "In addition, it is important to take note of refractive errors and surprises even in patients who are happy with the outcome. Even if that patient is accepting of residual refractive error, your next patient may not be," Dr. Khandelwal said. such as for white cataracts, nuclear sclerotic cataracts, and eyes with staphylomas and retinal detachments for combination retinal cases where the anatomy is not clear. In terms of which formula to use, Dr. Khandelwal said she compares at least two formulas with two different biometries, when possible. "I most often use the more modern formu- las because they have been shown to work well in most eyes, including outliers like longer axial length and shallow anterior chamber depth. For me, the easiest to access with my biometry are the Barrett and Holladay on the IOLMaster 700 and Olsen and Hill-RBF on the LENSTAR [Haag-Streit]," Dr. Khandelwal said. Certain scenarios might require specific ad- justments. Dr. Holladay said that recent studies have shown the Barrett Universal II, Olsen II, and Holladay 2 to perform between 78% and 80% within ±0.50 D. Dr. Khandelwal said she will use the Holladay 1 with the Wang-Koch axial length modification, the Barrett formula, and the Olsen or Hill-RBF, if available, for long eyes. For shorter eyes and those with shallow anterior chambers, she likes to use three formu- las "because it can be difficult to decide which lens." "I aim plano or a little hyperopic for these eyes, especially if they are already hyperopic pri- or to surgery. They are, ironically, the one group About the doctors Jack Holladay, MD Clinical professor of ophthalmology Baylor College of Medicine Houston Sumitra Khandelwal, MD Assistant professor of ophthalmology Baylor College of Medicine Houston Reference 1. Norrby S. Sources of error in intraocular lens power calcu- lation. J Cataract Refract Surg. 2008;34:368–76. Financial interests Holladay: Holladay Consulting Khandelwal: None

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