APR 2013

EyeWorld is the official news magazine of the American Society of Cataract & Refractive Surgery.

Issue link: https://digital.eyeworld.org/i/119916

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Page 28 of 82

26 EW CATARACT April 2013 Complicated cataract cases Moderate postoperative refractive error in the first eye by William Trattler, MD T here are many reasons why patients experience unintended postoperative refractive errors following cataract surgery. Lens power errors remain one of the most common reasons for litigation in ophthalmology. Frequent causes include transcription errors if the biometry and calculations are performed on different instruments; poor corneal curvature measurements; incorrect effective lens position (ELP) calculation; incorrect recording of the patient's desired postoperative refraction; ordering the wrong lens; and implanting the wrong lens despite ordering the correct lens. In rare cases, the lens in the manufacturer's box may simply not contain the labeled power. Standard keratometers see only the 3 mm optical zone. If a cornea is irregular or has undergone refractive surgery, the central cornea may have a different power than the mid-peripheral cornea. ELP errors are especially common nowadays, particularly after keratorefractive surgery, but may also be seen in otherwise normal eyes when the anterior segment is unusually crowded or deep for the axial length of the eye. Implanting the wrong lens is always a hazard when numerous IOLs are strewn around the operating room. At UCLA we have a special yellow box into which the lens to be implanted is placed after it is confirmed by the surgeon. In this article, William Trattler, MD, discusses his approach to the cataract patient who experiences a moderate refractive error following surgery in the first eye. This is a problem every surgeon will experience—hopefully, rarely. A chieving success in cataract surgery requires far more than being a skilled surgeon. It requires careful preoperative planning to provide the best opportunity to end up with a satisfied patient. Patients have very high expectations that they will end up with excellent uncorrected vision following surgery. While it can be challenging for both the surgeon and the patient when moderate postoperative refractive error occurs following cataract surgery in the first eye, it is definitely possible to end up with a happy patient by working with the patient to determine the best course of action. The first step is to evaluate the patient and understand the reasons for ending up off target in the first eye. Besides confirming that the correct IOL power was placed in the eye, other important steps include repeating the keratometry and biometry to confirm that the preoperative measurements were accurate. One common cause for inaccurate preoperative keratometry is dry eye, so evaluation of the ocular surface is another important step. Additional tests would include topography to rule out early keratoconus or irregular astigmatism, as well as OCT of the macula. A careful dilated slit lamp exam to ensure that the IOL was centered and positioned completely in the capsular bag is another important test. For patients with the Crystalens (Bausch + Lomb, Rochester, N.Y.), it is important to examine for Z-syndrome, which is easier to treat if it is identified sooner. In general, when a patient ends up off target, evaluation of the preoperative data and performing additional postoperative diagnostic tests will typically reveal the source for ending up off target. Once the source of the residual refractive error has been determined, then the decision can be made in conjunction with the patient to either address the first eye primarily to improve the uncorrected vision or proceed to cataract surgery on the second eye. Perhaps the most common scenario in 2013 for residual refractive error following cataract surgery is related to patients who have previously undergone corneal refractive surgery, including surface ablation, LASIK, RK, LTK, CK, and ALK. In these patients, carefully reviewing the IOL calculations can potentially reveal why there was residual refractive error in the first eye, and adjustments can be made for planning the second eye. In particular, IOL calculations in eyes with previous PRK, LASIK, or RK can be entered into the Kevin Miller, MD, Complicated cataract cases editor Post-LASIK patients are a common source of moderate postoperative refractive errors. Source: William Trattler, MD

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