Eyeworld Daily News

10 | EYEWORLD DAILY NEWS | APRIL 23, 2022 ASCRS ANNUAL MEETING DAILY NEWS A SCRS Refractive Day had a special focus on refractive image quality (IQ). The first session of the day took a look at how to understand and evaluate IQ, both central and peripheral. Marcony Santhiago, MD, PhD, described assessing IQ with corneal topography and tomography. Some corneal issues that could affect IQ are obvious, Dr. Santhiago said, but some are subtle, so we need to look at topog- raphy, especially in the center (on the visual axis) but not only there. He said that a wide range of topographical pat- terns could decrease image quality, but the hallmark is any type of asymmetry. Corneal topography, in addition to giving information about what could be impacting IQ, can also help in treatment, as in topography-guided PTK, for example. Dr. Santhiago said topography-guided treatment is advan- tageous over wavefront-guided because it's easier to obtain more reliable maps in highly aberrated corneas, and the ablation pattern saves tissue where it matters most. Following, Julie Schallhorn, MD, discussed the role of the epithelium on IQ. Dr. Schallhorn said the epithelium has a significant refractive impact. The epithelium remodels in response to surgical and external forces, trying to undo any shape change we make to the cornea, she said, noting that there is a trend toward regression as the epithe- lium heals. Dr. Schallhorn described the epi- thelium as like the frosting on a cake; it's not static, it moves around, and fills in the nooks and crannies of the cornea. Modeling has shown that the epithelium thickens where the cornea is less steep and thins where the cornea is steeper. Knowing this, Dr. Schallhorn continued, is key to understanding how the epithelium affects image quality. One of the most dramatic examples is keratoconus, where the epithelium tries to make the cone flatter, thick- ening in some areas and thinning in others, masking the cone and helping out visual acuity. When it comes to refractive patients, Dr. Schallhorn said it's important to understand what's going on with the epithelium in the healing process (because it's variable among patients) before considering a retreatment. A stable and predictable epithelium is key for good refractive outcomes, she said. The role of functional testing in evaluating IQ was described by Kendall Donaldson, MD. She discussed how we measure quality of vision—objectively with Snellen acuity or subjectively with patient reporting. Even if the patient is 20/20, there are still some who are unhappy with their vision, she noted. How can we differentiate between visual acuity and visual function? First, ask the patient, Dr. Donaldson said. Questionnaires are helpful for this but few are incorporated into clinical practices. There are four functional tests to assess quality of vision, which Dr. Donaldson said include glare testing, contrast sensitivity, reading speed, and stereoacuity. Objectively, some diag- nostic tools can be used to correlate structural problems with functional problems. Topography and tomogra- phy, for example, can detect residual or irregular astigmatism, OSD, HOAs, and angle kappa and alpha, Dr. Donaldson said. Other helpful tools she mentioned include macular OCT, iTrace (Trac- ey Technologies), and OPD Scan-III (Nidek). Vance Thompson, MD, elaborated on patient-reported outcomes (PROs), which he described simply as a mea- sure of the patient's perception of their health status or quality of life. While studies focus on objective measures to evaluate success, Dr. Thompson said that patients care about their vision (not what we measure), so success measurements should include PROs. Dr. Thompson described the PROWL studies as an example of research evaluating PROs. With the findings, the authors were able to derive conclusions that could answer some patients' preop questions (like that LASIK patients experienced an improvement in night vision and a decrease in glare, halo, and dryness) and could help set patient expectations (like that patients should expect a transient increase in dryness and halos in the first 3 months and that those without any preop symptoms may experience an increase but those with preop symptoms may see an improvement). Other presentations in the session covered positive and negative dyspho- topsia, applications for small-aperture devices, and peripheral vision. Editors' note: The speakers have financial interests with several ophthalmic companies. Evaluating and understanding refractive IQ Dr. Thompson discusses the importance of including patient-reported outcomes when considering measures of success.

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