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T opography-guided custom ablation treatment (T-CAT) corrects first- and second-order refractive abnormali- ties based on clinical refractions and higher order aberrations (HOA) based on corneal topography. In 2013, the FDA approved T-CAT LASIK for the treatment of eyes with myopia and myopic astigma- tism. 1 Clinical trial of T-CAT was conducted on sub- jects who had not undergone previous corneal refractive surgery or demonstrated pathology other than refractive error, and outcomes in normal sub- jects were outstanding, objectively and subjectively. Treatment was indicated for the reduction or elimi- nation of up to –9.00 D of spherical equivalent my- opia or myopia with astigmatism, with up to –8.00 D of spherical component and up to –3.00 D of astig- matic component at the spectacle plane. Throughout the clinical trial, the 3 devices used to plan and perform the topography-guided LASIK treatments were the ALLEGRETTO WAVE EYE-Q 400 Hz laser system (Alcon, Fort Worth, Texas), ALLEGRO Topolyzer topography system (Alcon), and T-CAT software for treatment planning. The meticulous attention to the accurate acquisition and selection of at least 4 corneal topographic images was critical to the outstanding clinical outcomes that were obtained during the clinical trial. Outcomes Subjects in the clinical trial reported an improvement in parameters measured by the Refractive Status and Vision Profile (RSVP), including physical/social func- tioning, driving, visual symptoms, optical problems and problems with corrective lenses that were evi- dent at 3 months and continued to improve through 12 months 1 ; 98.4% of subjects stated that they were satisfied with their outcomes and would have T-CAT LASIK treatment again. 1 Data derived from the FDA clinical trial demonstrated that T-CAT LASIK is a safe and effective treatment for myopia and myopic astigmatism. While the primary end point looked at changes in BSCVA vs. baseline, a post hoc analysis showed an increase in UCVA postoperatively compared to BSCVA preoperatively, an increase in BSCVA compared to preoperatively, and an improvement in visual symp- toms. At 3 months postoperatively, 31.6% of eyes achieved a UCVA of 20/12.5 or better; 68.9% of the eyes had a UCVA of 20/16 or better; and 92.7% of eyes had a UCVA of 20/20 or better. At 12 months, 34.4% of eyes saw 20/12.5 or better; 64.8% of eyes saw 20/16 or better; and 92.7% of eyes saw 20/20 Reference 1. FDA device approvals website, Topography-guided Custom Ablation Treatment or T-CAT Summary of Safety and Effectiveness Data (SSED), available at: www.fda.gov/MedicalDevices/ProductsandMedical- Procedures/DeviceApprovalsandClearances/Recently- ApprovedDevices/ucm372964.htm. or better 1 (Figure 1). Eyes treated with T-CAT demon- strated a shift toward an improvement in UCVA with time. In total, 89.9% of eyes were seeing at least as well without correction postoperatively as they did with best spectacle correction preoperatively. 1 Wavefront customized LASIK treatment is informally considered the standard of care in the U.S. by many. So if wavefront-guided treatment is the standard of care, why should we consider T-CAT? Topographic measurements are advantageous because they are static, reproducible, independent of pupil size, provide better peripheral data, provide more measurement points, and are based on the cornea where most visual aberrations are created. Topography gives a better measurement of highly aberrated corneas, which may create artifacts with wavefront sensors because of severely misdirected light rays. Applying the lesson The FDA study and its outcomes have taught us that in order to gain the most from T-CAT, the surgeon has to be familiar with the procedure, detail-oriented, and an active participant in topographic image acquisition to achieve these results. The payoff is a unique new technology on a platform that offers tremendous potential for an improvement in uncor- rected visual acuity, an improvement in best specta- cle corrected acuity, and an improvement in certain visual symptoms. Figure 1. Cumulative postoperative UCVA (ETDRS) Applying T-CAT FDA study outcomes to clinical practices by Doyle Stulting, MD, PhD Dr. Stulting is the director of the Stulting Research Center at the Woolfson Eye Institute in Atlanta, and professor of ophthal- mology emeritus at Emory University. He was medical monitor for the FDA clinical investigation of T-CAT LASIK performed with the Alcon WaveLight ALLEGRETTO WAVE Eye-Q excimer laser. Dr. Stulting is a consultant for Alcon. He can be contacted at dstulting@woolfsoneye.com. 5

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