PRO Measure for Refractive Surgery IRAS Project Number 246072

Specific aims of the study The investigators aim to take a novel PRO questionnaire from the conceptual framing stage through a well-defined validation pathway including cognitive interviews, field data collection in the target population, and Rasch modification. Secondary aims are to take the modified instrument through prospective studies of repeatability and sensitivity to change. The investigators´ ultimate goal is to develop a concise, screen based, self-administered, self-archiving and self-scoring PRO instrument for use as part of the National Dataset in Refractive Surgery.

Study Design

Step 1. Conceptual framing and draft development Conceptual framing and draft development for the questionnaire is complete. This was based on a comprehensive literature review, patient and surgeon feedback during RCOphth Refractive Surgery Standards development consultation, and advice from a panel of expert collaborators.

The investigators began with a literature review of existing refractive error specific questionnaires, including the following: (1) National Eye Institute Refractive Quality of Life (NEI-RQL), (2) Refractive Status and Vision Profile (RSVP), (3) Quality of Life Impact of Refractive Correction (QIRC), (4) Quality of Vision (QoV), (5) Canadian Refractive Surgery Research Group Quality of Vision Questionnaire (QVQ), (6) PERK Study Questionnaire, (7) Multidimensional Quality of Life for Myopia (MQLM) Scale, (8) Myopia-Specific Quality of Life Questionnaire (MQLQ), (9) Subjective Vision Questionnaire (SVQ), (10) Refractive Error Quality of Life Scale (REQ-Thai), (11) The Freedom from Glasses Value Scale (FGVS), (12) Near Activity Visual Questionnaire (NAVQ), Catquest questionnaire (CatQuest 9SF), and ocular comfort index (OCI).

Those questionnaires have been identified as refractive error specific in a recent review article published in JRS. The ocular comfort index (OCI) addresses ocular surface irritation. Unlike previous instruments designed to measure eye comfort such as the widely used ocular surface disease index (OSDI), it is unidimensional and was developed using Rasch fitting.

According to FDA recommendations, a conceptual framework is helpful in guiding the development of a PRO instrument . Following these recommendations, the investigators first identified the aspects of PRO for refractive surgery to be measured. Each of these aspects or "domains" is measured by a set of items. The investigators identified and included the following subscales:

• Spectacle dependence
• Quality of vision
• Ocular comfort symptoms /Eye comfort (Eye comfort is used in the questionnaire)
• Freedom
• Looking and Feeling Well
• Overall satisfaction

Having defined the domains of interest, the next task was to reduce and adapt the pool of candidate questionnaire items. Winnowing refers to reducing the item pool to the smallest number of items, making sure that the domain of interest will still be adequately measured. DeWalt et al. stated that winnowing helps to accurately define and identify those item characteristics relevant to each domain. Items are deleted if they are considered to duplicate the information captured, or if they are deemed to be potentially confusing to respondents. The investigators focused preferentially on items from Rasch weighted instruments. The investigators also reviewed items within each domain attempting to ensure, with input from patients and experts, that the most relevant aspects of each domain are captured by the item sets in the draft instrument. The investigators intended to keep a set of non-redundant items that are consistent with the domain, universally understood, and relevant to a wide range of the adult population. Items were revised so they would be understood by the largest possible number of people. In addition, consistency was sought to the extent possible in wording, recall interval, and response options.

The investigators opted to use four response options based on a balance between parsimony and adequate sampling. Both the most widely used current instruments (QIRC and CatQuest), after Rasch modification in development, focus on four response option scales.

To make items more universally understood, slight modifications to item stems and/or response options from their original form were made in those cases where we believed simplification was necessary. All changes in wording were then tested versus original versions in cognitive interviews. Items that were too long or confusing were shortened.

Step 2. Cognitive interviews Cognitive interviews will be conducted to optimise face validity (comprehensibility) of items and response options. Forty participants will be recruited from the waiting rooms of the Refractive Surgery Service at Moorfields Private Eye Hospital (Consultant Bruce Allan MD). The sample should include 20 males and 20 females of different age and educational background (highest degree). A trained interviewer (Andreas Frings MD) will conduct all of the cognitive interviews. Participants will be asked to describe in their own words what each item is asking, and in some cases to compare different ways of asking the same question. These interviews will be helpful because subjects can directly provide input and suggestions on every item considered for inclusion. As a result of these interviews, items could be further simplified, some words could be deleted, some items could be reworded, and some parts of the stems could be added to response options for clarity. The revised survey will then be used for field testing.

Step 3. Field testing and item calibration After questionnaire refinement resulting from cognitive interviews, the investigators will gather completed questionnaire data from a representative cross-section of the target patient population for Rasch fitting. Step 2 is the major component of the validation study and is described in detail below.

Inclusion criteria

Refractive Surgery

Exclusion criteria

Participation denied.