Efficacy of Coloured Overlays and Lenses for Reading Difficulty
Condition: Vision Disorders; Reading Disabilities
MeSH terms: Vision Disorders; Dyslexia
Study type: Interventional

Summary: 
      This is a randomised controlled trial with the aim of testing the efficacy of coloured
      overlays and coloured lenses for the relief of visual stress and reading difficulties in
      children and young adults.
    

Detailed description: 
      Participants will be adults aged from 8 years, with symptoms of visual stress (discomfort
      when reading or experiencing perceptual symptoms when reading such as letters moving or
      distorted) or with a diagnosed reading difficulty (dyslexia). Participants will be recruited
      from the City University London optometry clinic and the City University London Learning
      Success unit. Participants within this age range and with visual stress will be eligible to
      participate. Potential participants with an ocular or systemic condition with possible impact
      on vision (e.g. amblyopia or diabetes respectively) or with intellectual disability will be
      excluded from the study. Each potential participant will undergo an eye examination prior to
      participation, during which the following tests will be conducted:

      Prior to study entry:

      History and symptoms Direct ophthalmoscopy (to check for ocular abnormality) Retinoscopy and
      subjective refraction (to quantify corrected and uncorrected refractive error) Cover tests
      (to look for any eye misalignment)

      Baseline tests on study entry:

      Each eligible participant who agrees to take part in the study will undergo testing with
      coloured overlays, to determine whether a particular overlay appears to be beneficial in
      terms of reducing difficulty or discomfort while reading. If so, the participant will be
      provided with the overlay to use for a period of two weeks, to determine whether it is
      consistently beneficial when reading during that period. In addition, the Wilkins Rate of
      Reading Test (WRRT) will be carried out at this baseline stage with and without the overlay.

      Follow-up test 1:

      The participant will attend a further appointment at the two week time point, and if the
      overlay was beneficial, an addition test will be carried out using the Intuitive Colorimeter,
      to determine the exact hue, saturation and intensity of coloured lenses that offer the most
      relief from difficulty or discomfort while reading. Once this colour has been determined, the
      hue will be modified to find the closest colour at which the participant first loses benefit
      (the point at which the discomfort or difficulty returns). Each colour setting (beneficial
      and non-beneficial) will be noted and the participant will be provided with spectacle lenses
      tinted exactly to one of these colour specifications. In a crossover design, the order in
      which true or control lenses will be provided to each participant will be determined by
      random number generation. Allocation will be carried out by personnel who are not researchers
      on this study, and who know the order (true lens tint first or second) as 1 and 2. Ordering
      of tinted spectacles will be handled by the personnel who are not researchers on the study,
      and this information will not be accessible by the researchers. Thus, tinted lens ordering
      will not be shared with the researchers, who will not know whether each participant is
      wearing the beneficial or non-beneficial tint, and so will be masked. Similarly, participants
      will be unaware whether they are wearing the true or control tint, at any time during their
      participation. The non-beneficial tint will be very similar to the beneficial tint, so
      neither researchers nor participants will be able to determine this. On this occasion the
      participant will also be asked to describe the difficulties he/she has experiences when
      reading with and without the coloured overlay.

      Follow-up test 2:

      After one month wearing the first pair of tinted lenses, reading speed will be measured again
      with the first pair of tinted lenses, and the participant will be asked again about their
      experience of reading difficulties while wearing these glasses. The participant will be asked
      to spend one week without any tinted lenses, and to return for a further visit after that
      week. After this period, the second pair of tinted lenses will be provided, to be worn for a
      further month.

      Follow-up test 3:

      Reading speed will be measured again with the second pair of tinted lenses and the
      participant will again be asked about their experience of reading difficulties while wearing
      these glasses.

      Statistical analysis The main outcome measures are rates of reading provided by the two
      reading tests, with the two tinted lens types, the overlay, and without any tint. These are
      quantitative tests and the results will be compared between the two groups using an unpaired
      t-test, and within individuals (between baseline and follow-up tests) using a repeated
      measures analysis of variance. In addition, qualitative data are obtained from participants'
      descriptions of their experience of reading difficulty at different stages of the study.
      These responses will be analysed using NVivo software to look for themes.
    

Intervention name(s): Precision tinted lenses; Non-beneficial tinted lenses
Intervention type(s): Device; Device
Intervention description(s): Tinted lens for patient with reading difficulty or visual stress; Tinted lenses that are unlikely to help reading difficulty or visual stress
Allocation: Randomized
Intervention model: Crossover Assignment
Masking: Double (Participant, Investigator)
Primary purpose: Treatment