Date of Award
Master of Science in Vision Science
Robert L. Yolton
Introduction: lrlen has suggested that many persons with reading problems have a condition called Scotopic Sensitivity Syndrome (SSS). SSS can be assessed by using the lrlen Differential Perceptual Schedule (lOPS), and treated by the use of colored filters. However, the value of filter therapy remains controversial. The primary goal of this project was to determine the effects of colored lrlen filters on eye movements made during reading.
Subjects: Twenty-nine subjects with different reading abilities were recruited. Ages ranged from 8 to 39 years, grades ranged from 3rd to post-graduate. Based on the lOPS, 7 had low SSS levels, 15 had moderate levels, and 3 had high levels.
Methods: A certified lrlen screener selected the best, next to best, next to worst, and worst colors from the lrlen overlay set. Eye movements were analyzed by an Ober2 system as subjects read through these filters. In addition they read through a clear filter and without a filter. Reading levels of the paragraphs were equated across subjects based on data from the Dyslexia Determination Test (DDT) or the Adult Dyslexia Test (ADT).
Results: Grouped data for all subjects showed no significant effects of the overlays. Data for the moderate and high SSS subjects also showed no significant overlay effects. One subject did seem to benefit significantly from the use of an overlay.
Discussion: For the majority of subjects considered in this study, the use of lrlen overlays could not be shown to have significant value. Reasons for the failure to show benefits include the possibility that effects of the filters take several months of use or significant fatigue to become manifest, or that the paragraphs used in the study were too "easy" for the subjects. It is also possible that any benefits were below the detection threshold for the Ober2 system, or that the lrlen filters simply did not have an effect on eye movements for the majority of subjects.
Hansson, Elin, "Use of eye movements measured during reading as an objective assessment of the benefits provided by irlen color filters" (1995). College of Optometry. 1331.