Eyeworld

EW CATARACT 28 May 2016 by Maxine Lipner EyeWorld Senior Contributing Writer disease prior to cataract surgery," she said. "Patients aren't going to always present with symptoms of dry eye so you can't rely on symptoms alone." sensitivity of the cornea from dam- aging effects of dry eye might be a contributing factor to the lack of symptoms, despite advanced surface signs of dry eye. "This points to the need for objective testing for dry eye osmolarity and 25 with normal osmolarity. Each eye was measured 2 different times, up to 3 weeks apart. Investigators found that there was a statistically significant higher variability in the average K readings in the hyperosmolar group. "We found that 10% of these hyperosmo- lar patients had a difference in IOL calculation of 0.5 D or more," Dr. Epitropoulos said. "That's signifi- cant, especially in patients interest- ed in premium lenses, but it's also significant even in patients with traditional lenses." In addition, vec- tor analysis of patients' keratometric cylinder showed that 17% of hyper- osmolar eyes had greater than 1 D of cylinder difference between the 2 presurgical visits. "Hyperosmolar- ity of the tears was associated with reduced repeatability of preoperative IOL calculation measurements," Dr. Epitropoulos said. When subjects were grouped by self-reported dry eye, the difference was not statistically significant. "Pa- tients presenting for cataract surgery do not generally verbalize symptoms all of the time," Dr. Epitropoulos said. One theory is that reduced Studying the effect of tear osmolarity in cataract surgery planning W hat role does tear osmolarity have on the repeatability of keratometry mea- surements in patients presenting for cataract surgery? Results from a study published in the August 2015 issue of the Journal of Cataract & Refractive Surgery indi- cated that those with hyperosmo- larity had a statistically significant higher variability in the average K reading used for IOL power calcu- lations than those in the normal osmolarity group, according to Alice Epitropoulos, MD, clinical assistant professor, The Ohio State University Medical Center, and the Cataract & Refractive Center of Ohio, Colum- bus, Ohio. Such measurements have an important role in post-cataract visual acuity. "Accurate IOL power calculations are essential to ensure good uncorrected vision after cata- ract surgery," Dr. Epitropoulos said. "This is especially true for patients who are interested in premium lenses because an accurate refractive outcome is so important to patient satisfaction." A key component to all IOL power calculation formulas is accurate measurement of anterior corneal curvature as measured by keratometry, she said, adding that this can vary significantly if the ocular surface is unstable. Investigating hyperosmolarity "Precise keratometry relies on a good reflection of the mires from the corneal surface," Dr. Epitropoulos said. Because an unstable tear film reduces the quality of corneal reflection, this can compromise the K readings. With this in mind, investigators hypothesized that it is of consider- able value to identify patients with a compromised ocular surface and accompanying tear film instability prior to cataract surgery, Dr. Epitropoulos reported. By identi- fying this group, the hope was to increase confidence in K readings with appropriate treatment. Included in the study were 50 patients presenting for routine cataract surgery who had hyper- Keying in on keratometry The TearLab Osmolarity System tests for hyperosmolarity in the tear film, a hallmark of dry eye disease. Source: Alice Epitropoulos, MD continued on page 30 " Accurate IOL power calculations are essential to ensure good uncorrected vision after cataract surgery. This is especially true for patients who are interested in premium lenses because an accurate refractive outcome is so important to patient satisfaction. " –Alice Epitropoulos, MD

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