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Original Investigation
January 2017

Assessment of the Psychometric Properties of a Questionnaire Assessing Patient-Reported Outcomes With Laser In Situ Keratomileusis (PROWL)

Author Affiliations
  • 1Department of Medicine, UCLA (University of California, Los Angeles)
  • 2Center for Devices and Radiological Health, US Food and Drug Administration, Silver Spring, Maryland
  • 3Department of Psychology, UCLA
  • 4Department of Ophthalmology, Navy Refractive Surgery Center, Naval Medical Center San Diego, San Diego, California
  • 5The Emmes Corporation, Rockville, Maryland
  • 6Division of Epidemiology and Clinical Applications, National Eye Institute, Bethesda, Maryland
  • 7Viewpoint Editor, JAMA Ophthalmology
JAMA Ophthalmol. 2017;135(1):3-12. doi:10.1001/jamaophthalmol.2016.4597
Key Points

Question  What are the psychometric properties of a patient-reported outcome instrument to assess eye-related symptoms and their effect on functioning and well-being following laser in situ keratomileusis (LASIK)?

Findings  The Patient-Reported Outcomes With LASIK (PROWL) studies (PROWL-1 and PROWL-2) were prospective observational studies evaluating a total of 574 patients undergoing LASIK surgery for myopia, hyperopia, or astigmatism. The study results support the reliability and validity of these patient-reported outcome measures for use in evaluating LASIK surgery.

Meaning  These studies yield support for use of the PROWL survey in future studies to assess the effects of LASIK surgery on functioning and well-being.


Importance  Patient-reported outcome (PRO) measures for laser in situ keratomileusis (LASIK) are needed.

Objective  To develop PRO measures to assess satisfaction, eye-related symptoms, and their effect on functioning and well-being following LASIK based on patient and expert input.

Design, Setting, and Participants  The Patient-Reported Outcomes With LASIK (PROWL) studies were prospective observational studies of patients undergoing LASIK surgery for myopia, hyperopia, or astigmatism. PROWL-1 was a single-center study of active-duty US Navy personnel and PROWL-2 was a 5-center study of civilians. PROWL-1 enrolled 262 active-duty service personnel and PROWL-2 enrolled 312 civilians 21 years or older who spoke English; 241 individuals in PROWL-1 and 280 in PROWL-2 completed a baseline questionnaire before surgery. The analytic sample included those also completing 1 or more follow-up questionnaires: 240 (99.6%) of those in PROWL-1 and 271 (94.4%) of those in PROWL-2. Questionnaires were self-administered through the internet preoperatively and at 1 and 3 months postoperatively in both studies and at 6 months postoperatively in PROWL-1. PROWL-1 began in August 2011 and was completed May 30, 2014; PROWL-2 began in July 2012 and was completed June 27, 2014. Data were analyzed from June 28, 2014, to October 24, 2016.

Main Outcomes and Measures  Scales assessing visual symptoms (double images, glare, halos, and starbursts), dry eye symptoms, satisfaction with vision, and satisfaction with LASIK surgery. Items from the National Eye Institute (NEI) Refractive Error Quality of Life Instrument (NEI-RQL-42), NEI Visual Function Questionnaire (NEI-VFQ), and the Ocular Surface Disease Index (OSDI) were included. All scales are scored on a 0 to 100 possible range. Construct validity and responsiveness to change were evaluated (comparing scores before and after surgery).

Results  The median age of the 240-person PROWL-1 analytic sample was 27 years (range, 21-52 years); 49 were women (20.4%). The median age of the 271-person PROWL-2 analytic sample was 30 years (range, 21-57 years); 147 were women (54.2%). Internal consistency reliabilities for the 4 visual symptom scales ranged from 0.96 to 0.98 in PROWL-1 and from 0.95 to 0.97 in PROWL-2. The median (interquartile range) test-retest intraclass correlation was 0.69 (0.57-0.79) and 0.76 (0.68-0.84) in PROWL-1 and PROWL-2, respectively. Product-moment correlations of satisfaction with surgery with visual symptom scales at follow-up evaluations ranged from r = 0.24 to r = 0.49. Measures improved from baseline to follow-up, with effect sizes of 0.14 to 1.98, but scores on the NEI-RQL-42 glare scale worsened at the 1-month follow-up. Hours of work did not change significantly from baseline to 1-month follow-up, with the mean number (mean [SD] difference) in PROWL-1 of 41.7 vs 40.9 hours (−0.8 [18.7]) and in PROWL-2 of 38.8 vs 38.2 hours (−0.6 [17.1]).

Conclusions and Relevance  The results of these studies support the reliability and validity of visual symptom scales to evaluate the effects of LASIK surgery in future studies.