ASCRS Responds To PROWL Study

You might be asking yourself, “What is PROWL?”

PROWL is Patient Reported Outcome with LASIK. It was started by the FDA (Food and Drug Administration) in 2009 in order to better understand the risk and potential problems that can result from LASIK. Furthermore, the project was set in motion to determine the percentage of patients who develop difficulties performing regular activities following LASIK.

Method

Two versions were conducted 1) military and 2) non-military. PROWL-1 was completed in 2014 with a total of 262 participants using a questionnaire to determine patient reported outcomes (PRO). The intent of PROWL-1 was to develop a questionnaire to better evaluate patient reporting of visual symptoms, and then assess the potential of those symptoms to impact patient quality of life post-LASIK. In the wake of PROWL-1, PROWL-2 was completed in 2014 with 312 patients to further confirm the questionnaire. These analyses are the first study to evaluate the multiple aspects of a patient’s LASIK experience (expectations, satisfaction, visual symptoms and their impact on daily life).

What were the results?

The FDA reported that 45% of patients, who were free of symptoms prior, reported a new symptom in the first three months post-surgery. However, this did not affect the overwhelmingly positive response. 96% of patients reported being satisfied with their vision in the following 3 months after their procedure.

What you need to know (Statistics provided by ASCRS)

• Common findings in PROWL-1 and PROWL-2 trials
• Only one of 990 eyes lost three 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 six 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 (Six Months)
• 99% of patients had a binocular uncorrected vision of 20/20 or better at three months.
• When asked how satisfied patients were with the results of their LASIK surgery, 98% reported being satisfied at six months and 2% were dissatisfied. When asked “How satisfied are you with present vision?”, 97% were satisfied at six months and 3% were dissatisfied. This is a significant improvement, since 73% were dissatisfied preoperatively.
• 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, three times more patients reported the resolution of pre-op 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 pre-op Ocular Surface Disease Index (OSDI) noted mild, moderate or severe dry eye at six months. While 65% of patients with pre-op mild, moderate or severe dry eye symptoms had normal OSDI scores at three months. Thus, three 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 (Three Months)
• 96% of patients had binocular uncorrected vision of 20/20 or better at three months.
• 97% were satisfied with their LASIK surgery at three months.
• 96.2% were satisfied with their vision at three 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 three 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 three months) in all patients following LASIK. 35% of subjects who had no halos prior to surgery developed new halos at three months. This was a subset of 31 patients out of the 260 patients examined at three months. The instances where preoperative symptoms (such as halos) disappeared following surgery were not presented.
• 28% of subjects who had a normal pre-op OSDI noted mild, moderate or severe dry eye at three 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.

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