Names and terminology
In brief: Irlen syndrome was earlier called scotopic sensitivity syndrome and is sometimes called Meares-Irlen syndrome; the Irlen organizations equate it with visual stress, but EyeWiki says the terms are not interchangeable.[1][2][3]
The names
| Name | How it is used | Source |
|---|---|---|
| Scotopic sensitivity syndrome (SSS) | Helen Irlen’s early term; the Institute now says “formerly known as” | [1] |
| Irlen syndrome | The Institute’s current name; a proposed construct tied to its assessment | [1] |
| Meares-Irlen syndrome | Acknowledges Olive Meares’s early 1980s descriptions; transitional term | [2] |
| Visual stress / pattern-related visual stress | Broader research concept for discomfort and distortions from patterns, including text | [3] |
| MISViS | Umbrella label, Meares-Irlen syndrome/visual stress | [3] |
Scotopic sensitivity syndrome
The foundation explains that Irlen first called the condition scotopic sensitivity syndrome because she believed the difficulties arose when the brain processed light in the scotopic range, and that the label was dropped partly because people read it as meaning night vision.[2] EyeWiki calls the term scientifically inaccurate because there is no evidence that the symptoms come from rod dysfunction.[3]
Olive Meares
Olive Meares, a teacher in New Zealand, described similar reading-related visual complaints in the early 1980s; the foundation notes that she did not go on to develop a treatment protocol.[2] Her 1980 paper appears, spelled “Mears,” in the Institute’s bibliography.[4]
Visual stress
The foundation says optometrists introduced the term visual stress to simplify the name, and treats all the labels as the same condition.[2] EyeWiki disagrees: it says Irlen syndrome, Meares-Irlen syndrome, scotopic sensitivity syndrome and visual stress are not interchangeable, and that visual stress is a broader research concept studied with published methods such as the Intuitive Colorimeter and the Wilkins Rate of Reading Test.[3]
Why the distinction matters
Statements against Irlen lenses mainly concern the proprietary Irlen assessment and should not be read as denying that some people experience discomfort from visual patterns, according to EyeWiki.[3] Conversely, research on visual stress does not validate the Irlen assessment or Irlen filters specifically, and EyeWiki notes that results for colored filters in visual stress are themselves inconsistent.[3]
Proposed criteria for visual stress
Unlike Irlen syndrome, visual stress has published draft diagnostic guidelines. EyeWiki summarizes a Delphi study proposing at least three characteristic symptoms plus at least two findings among: voluntary use of an overlay for at least three months, an improvement of at least 15% on the Wilkins Rate of Reading Test, or an abnormal pattern glare test, after a full eye examination by a regulated eye-care professional.[3] The foundation’s article adds sensory processing disorder and visual processing problems to the list of names it treats as equivalent.[2]
How the Institute uses the names
The Institute’s home page says the symptoms are known by many names, including Irlen Syndrome, visual stress and scotopic sensitivity.[5] Its self-test page refers to a visual processing problem like Irlen Syndrome or Visual Stress.[6] See Irlen syndrome.
Common questions
Is scotopic sensitivity syndrome the same as Irlen syndrome?
Yes; it was Helen Irlen’s earlier name for it.
What is Meares-Irlen syndrome?
A name that credits Olive Meares’s early 1980s descriptions alongside Helen Irlen.
Is visual stress the same as Irlen syndrome?
The Irlen organizations treat them as the same; EyeWiki says they are not interchangeable.
Further pages
Citations
- ^ a b c The science. Irlen Institute (irlen.com). Retrieved 9 November 2026.
- ^ a b c d e f Everything you need to know about the different names for Irlen Syndrome (4 March 2022). Irlen Syndrome Foundation (irlensyndrome.org). Retrieved 9 November 2026.
- ^ a b c d e f g h Meares-Irlen syndrome/visual stress (MISViS), reviewed 25 September 2026. EyeWiki, American Academy of Ophthalmology. Retrieved 9 November 2026.
- ^ Bibliography of research. Irlen Institute (irlen.com). Retrieved 9 November 2026.
- ^ The Irlen Institute: home page. Irlen Institute (irlen.com). Retrieved 9 November 2026.
- ^ Irlen Syndrome self-test. Irlen Institute (irlen.com). Retrieved 9 November 2026.