title: A Delphi study to develop practical diagnostic guidelines for visual stress (pattern-related visual stress).
abstract: OBJECTIVE
  Visual stress (VS) is characterised by symptoms of visual perceptual distortions and eyestrain when viewing text, symptoms that are alleviated by individually prescribed coloured filters. A recent review supports the existence of VS and its treatment, but noted that controversy remains, in part due to inconsistencies in the diagnosis of the condition. The present paper reviews the diagnostic criteria for VS in the literature and reports a Delphi analysis of the criteria currently used in clinical practice.
  
  
  METHODS
  Twenty-six eyecare practitioners were invited to participate in a Delphi study. They were selected because they were frequent prescribers of precision tinted lenses. In the first round they were sent a list of the indicators for which there is literature to suggest a relevance in the diagnosis of VS. The practitioners were invited to rank the indicators and add any additional criteria they use in diagnosis. In the second round a revised list was circulated, including items added from the responses in the first round.
  
  
  RESULTS
  The respondents included optometrists, orthoptists and opticians. In the first round the response rate was 85%. Ninety-one percent of those who participated in the first round also responded in the second round. Strong indicators in the second round included the symptom of words moving when reading, voluntary use of an overlay for a prolonged period, improved performance of ≥15% with an overlay on the Wilkins Rate of Reading test, and an abnormally high score on the Pattern Glare Test.
  
  
  CONCLUSIONS
  The strongest diagnostic criteria are combined in a diagnostic tool. This is proposed as a guide for clinical practice and further research.
authors.affiliation: Institute of Optometry, London, UK; Division of Optometry & Visual Science, City, University London, UK. Electronic address: admin@ioo.org.uk.
authors.forename: Bruce J W
authors.initials: BJW
authors.lastname: Evans
authors.affiliation: Department of Vision and Hearing Sciences and Vision and Eye Research Unit, Anglia Ruskin University, Cambridge, UK.
authors.forename: Peter M
authors.initials: PM
authors.lastname: Allen
authors.affiliation: University of Essex, Department of Psychology, Colchester, UK.
authors.forename: Arnold J
authors.initials: AJ
authors.lastname: Wilkins
mesh_terms: D001248:Asthenopia / Q000175:diagnosis* / Q000503:physiopathology; D003697:Delphi Technique; D019466:Glare; D006801:Humans; D000072162:Optometrists / Q000592:standards; D009907:Optometry / Q000592:standards*; D017410:Practice Guidelines as Topic / Q000592:standards*; D011932:Reading; D014792:Visual Acuity / Q000502:physiology*
keywords: Delphi study; Estrés visual; Estrés visual relacionado con patrones; Estudio Delphi; Lectura; Pattern-related visual stress; Reading; Visual stress