Eyeworld

EW INTERNATIONAL 58 January 2015 by Dan Reinstein, MD, MA(Cantab), FRCSC, DABO, FRCOphth, FEBO London Vision Clinic applies in-house research to improve outcomes A t the London Vision Clinic, we practice laser refractive surgery with the same goal in mind that everyone aspires to: to provide patients with the best possible outcomes. However, we do one thing differently: We run our everyday clinical practice to the standard of a clinical trial and con- stantly mine our data for examining and improving the practice. When I was starting out in refractive surgery in the 1990s, I was quite impressed by the standard and rigor of the first FDA clinical trials for excimer laser PRK that led to approval in the U.S. It made me wonder why I often saw a difference in rigor between clinical practice in a clinical trial and outside of clinical trials—particularly for a procedure that is constantly dependent on developments and refinements such as corneal laser eye surgery. When I established the clinic in 2002, I was effectively escaping the slower approval process in the U.S., and my intention from the beginning was to run the practice to the clinical standards of an FDA trial every day for every patient. We measure everything at every visit, including many ocular and visual parameters that are con- sidered "only research tools." We achieve more than 90% follow-up at 1 year, meaning that we exceed the FDA follow-up criteria for our entire patient population, not just a specific study population. This level of postoperative care is obviously good for an individual patient, but our patient population also bene- fits from our ability to answer any clinical question based on large population statistics, which we can use to improve our procedures and protocols. Using high quality past patient data in a continuous feedback loop increases the number of happy patients, and this is good for the referral rate. To achieve this, I made the investment of setting up a research department that accounts for about 10% of the staff at Lon- don Vision Clinic. This allowed me to continue my interest in research gained at Weill Medical College (New York) where I co-developed the Artemis very high-frequency digital ultrasound scanner (ArcScan, Morrison, Colo.), which has been the focus of much of my research, in particular describing the applica- tions for corneal epithelial thickness measurements. 1 Keratoconus screening by epithelial thickness measurements While topography, tomography, and screening algorithms based on these data have revolutionized the identification of mild keratoconus, there are still equivocal cases where a confident diagnosis cannot be made. I found that it was possible to confirm or exclude keratoconus in such cases according to the pattern of the epithelial thickness profile. As the epithelium always acts to com- pensate for stromal surface changes, there is thinning over the cone in keratoconus that masks the extent of the cone from front surface topogra- phy, but leaves a fingerprint in the epithelium as a localized region of thin surrounded by an annulus of thicker epithelium. This culture of exploring beyond the known factors can provide us with unique insight that can improve patient care and impact the bottom line. Some things you do in apply- ing analytical methods in clinical practice have a direct return on investment. At a time when doctors are rejecting approximately 9% of patients seeking LASIK based on suspected keratoconus topography, we were able to develop a method of proving that 84% of those rejected were in fact not keratoconic, leading to a 7% increase in our volume of surgery; investment in the Artemis very high-frequency digital ultrasound technology paid off relatively quickly with just this application alone. Diagnosis and management of refractive surgery complications London Vision Clinic is one of a small group of research teams working on methods of repairing irregular corneas. Our work has highlighted the importance of epithelial thickness measurements to understand the true cause of a patient's visual symptoms. Obtain- ing a picture of the stromal surface is the key in cases of irregular astig- matism. The masking effect of the epithelium means that any stromal irregularity will be partially or some- times almost completely smoothed by the epithelium so topography or wavefront will provide incomplete and sometimes misleading infor- mation. I have seen many instances where the wrong diagnosis has been made based on topography data alone, whereas the true story has been revealed by epithelial thickness mapping. We have published a number of papers describing the technique for Artemis-guided transepithelial PTK that uses the epithelium as a natural masking agent to target the ablation and smooth the peaks of an irreg- ular stromal surface. 2–6 We are also working on a pioneering technique to merge topography and epithelial thickness data to generate stromal surface topography data in order to treat the true irregularity in one procedure. 7 Being able to say to patients that I should be able to fix almost any complication that leads to corneal irregularities gives me great peace of mind when offering an elective procedure to someone who can already see—albeit with glasses. My philosophy is that we should be offering refractive surgery "with airbags." Presbyopia correction Another major research area over the last decade has been in devel- oping a LASIK method of treating presbyopia. My approach involves using a controlled induction of spherical aberration to increase depth of field, which combined with a micro-anisometropia can achieve clear vision at all distances and is far better tolerated than tradi- tional monovision. We designed the algorithm to get the benefit of depth of field, but without inducing excess aberrations that would reduce quality of vision as is the case with multifocal approaches, both corneal Practicing ophthalmology, the clinician scientist way Atlas corneal topography, Orbscan posterior elevation best fit sphere (BFS), and Artemis epithelial thickness profile for two example eyes where the diagnosis of keratoconus was misleading from topography. (Top) This case shows an eye where inferior steep- ening on topography and a slightly eccentric posterior elevation raise suspicion of keratoconus; however, the epithelial thickness profile excludes keratoconus as there is thicker epithelium in the location of the suspected cone. (Bottom) This case shows an eye where the topography is completely normal, but there is suspicion of keratoconus due to an eccentric posterior elevation. The epithelial thickness profile confirmed a diagnosis of keratoconus as there was an epithelial doughnut pattern coincident with the posterior surface elevation. Source: Dan Reinstein, MD, MA(Cantab), FRCSC, DABO, FRCOphth, FEBO

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