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November 2014



ASCRS responds to FDA PROWL studies



Preliminary results of the Food and Drug

Administration/National Eye Institute/Department of Defense LASIK Quality of Life Project were released during the 2014 American Academy of Ophthalmology (AAO) annual meeting. The multi-year study, which utilized the Patient Reported Outcomes with LASIK (PROWL) questionnaire, examined patient-reported outcomes (PROs) following LASIK. Two versions of the PROWL study were conducted: military (PROWL-1; 262 subjects) and non-military (PROWL-2; 312 subjects). The results are overwhelmingly positive and confirm the results of many other studies: More than 96% of subjects report being satisfied with their vision at 3 months following LASIK.

“In the 25 years since the FDA commenced their first excimer laser trial in 1989 for refractive keratectomy, LASIK has been shown in hundreds of clinical studies as a very safe and effective procedure for low to moderate levels of refractive error,” said ASCRS President Richard A. Lewis, MD. “The high rate of success is unprecedented as a surgical procedure. The collaborative work between military and non-military ophthalmologists in conjunction with the FDA in the PROWL-1 and PROWL-2 studies confirm the remarkable efficacy of LASIK. Our understanding of those at risk for dry eyes and visual disturbances from LASIK procedures is critical and evolving. The questionnaires developed in the PROWL studies will help identify those at risk. The questionnaires, however, must be used in studies as compared to a control group such as contact lens wearers, etc. Furthermore, a 3-month study is insufficient as the vast majority of these symptoms resolve with time. Identifying individuals at high risk for complications of LASIK is valuable. However, this must be determined in a well-controlled and timely trial.” The following summary was written by Ed Manche, MD, Eric Donnenfeld, MD, Doyle Stulting, MD, Kerry Solomon, MD, John Vukich, MD, and Daniel Durrie, MD, and outlines the FDA’s findings further.

The facts about the FDA PROWL studies

The PROWL-1 study, completed in 2014 with 262 participants, was conducted at the U.S. Naval Medical Center San Diego, using a questionnaire to determine patient-reported outcomes (PRO) in a patient population undergoing standardized treatment. The intent behind PROWL-1 was to develop a questionnaire to better evaluate patients’ reporting of visual symptoms and to assess the potential of those symptoms to impact a patient’s quality of life after LASIK. The PROWL-2 study, also completed in 2014 with 312 participants, was designed to further validate the questionnaire in a national, multicenter clinical study of a civilian population.  The FDA presented preliminary findings from both the PROWL-1 (6-month data) and PROWL-2 (3-month data) studies during the 2014 AAO annual meeting. With the studies completed and analyses underway, PROWL is the first prospective study to evaluate the multiple aspects of a patient’s experience with LASIK, including expectations, satisfaction, visual symptoms and their impact on daily life.

The preliminary findings confirm high patient satisfaction rates and provide more context to visual symptoms reported, such as ghosting, halos, starburst, and glare, along with dry eye, both preop and postop. As these findings are further analyzed, they will allow us, as physicians, to further enhance our discussions with patients about benefits and risks of LASIK surgery.

A very small set of the data collected has been analyzed, and we look forward to additional findings and analysis. While the FDA is obligated to look at the public health impact of these findings, it is the responsibility of the medical community to not only establish a foundation of unbiased scientific evidence about LASIK patient satisfaction, but also address that small percentage of dissatisfied patients and learn everything we can to improve LASIK satisfaction rates. We remain firm in our commitment to the ongoing work.

For more than a decade, LASIK—one of the most studied medical procedures—has been considered a safe and effective vision correction option for those who are nearsighted, farsighted, and/or have astigmatism. Millions of people have benefitted from LASIK. LASIK is surgery, and no surgery is 100% risk free. 

The PROWL findings: What you need to know

• Common findings in PROWL-1 and PROWL-2 trials › Only 1 of 990 eyes lost 3 or more lines of visual acuity, and that eye saw 20/25 or better.

› The prevalence of all visual symptoms and bothersome symptoms studied (ghosting, halos, glare, and starbursts) was less at 6 months after surgery without correction than it was preoperatively with best correction (PROWL-1).

› Patients reporting difficulty or the inability to perform usual activities due to visual symptoms improved or were completely eliminated following LASIK in both studies.

› Visual symptoms throughout these trials must be understood in the context that there was no correction of residual refractive error. While the results are excellent, they would be even better if patients had been given the option to have additional LASIK or to wear glasses.     • PROWL-1 summary (6 months)

99% of patients had a binocular uncorrected vision of 20/20 or better at 3 months.

When asked how satisfied patients were with the results of their LASIK surgery, 98% reported being satisfied at 6 months and 2% were dissatisfied.

When asked “How satisfied are you with present vision?” 97% were satisfied at 6 months and 3% were dissatisfied. This is a significant improvement, since 73% were dissatisfied preop.

For each symptom index, up to 30% of patients reported new visual symptoms, while 91% of patients reported the resolution of symptoms they had prior to LASIK. Thus, 3 times more patients reported the resolution of preop visual symptoms than reported new visual symptoms.

Very few patients reported that visual symptoms negatively impacted their daily activities.

21% (23 subjects) with a normal preop Ocular Surface Disease Index (OSDI) noted mild, moderate, or severe dry eye at 6 months. 65% of patients with preop mild, moderate, or severe dry eye symptoms had normal OSDI scores at 3 months. Thus, 3 times more patients experienced an improvement in OSDI after LASIK than noticed new OSDI symptoms. Subjects were not followed long enough to observe the resolution of the dry eye symptoms, which was reported to occur in the literature.

• PROWL-2 summary (3 months)

96% of patients had binocular uncorrected vision of 20/20 or better at 3 months.

97% were satisfied with their LASIK surgery at 3 months.

96.2% were satisfied with their vision at 3 months, while 3.9% were dissatisfied. This is an improvement since 55.9% were dissatisfied preoperatively. 

Up to 1% of subjects, without glasses or contact lenses, experienced a lot of difficulty with or were unable to do usual activities due to visual symptoms at 3 months. The ability of glasses or contact lenses to correct visual symptoms was not presented.

The prevalence of halos decreased from 51% (preoperatively) to 46% (at 3 months) in all patients following LASIK. 35% of subjects who had no halos prior to surgery developed new halos at 3 months. This was a subset of 31 patients out of the 260 patients examined at 3 months. The instances where preoperative symptoms (such as halos) disappeared following surgery were not presented.

28% of subjects who had a normal preop OSDI noted mild, moderate, or severe dry eye at 3 months. The percent of patients who had mild, moderate, or severe dry eye preoperatively, who had a normal OSDI postoperatively was not presented.

› The majority of the dissatisfied patients reported visual symptoms, such as glare, halos, ghosting or starbursts. The number of patients for whom refractive correction would have eliminated these symptoms was not presented.

Subjects were not followed long enough to evaluate the resolution of dry eye symptoms that typically occur after LASIK. Nor were they followed long enough to evaluate the long-term effects of LASIK.

Contact information

Cindy Sebrell:


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