Irlen syndrome: systematic review and level of evidence analysis

Miyasaka, Jordan Da Silva; Vieira, Raphael V. Gonzaga; Novalo-Goto, Elaine Shizue; Montagna, Erik; Wajnsztejn, Rubens

doi:10.1590/0004-282X20190014

Brasil

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View and Review • Arq. Neuro-Psiquiatr. 77 (3) • Mar 2019 • https://doi.org/10.1590/0004-282X20190014 linkcopy

Irlen syndrome: systematic review and level of evidence analysis

Síndrome de Irlen: revisão sistemática e análise do nível de evidência

Authorship SCIMAGO INSTITUTIONS RANKINGS

ABSTRACT

Background: Scotopic sensitivity syndrome, later called Meares-Irlen syndrome or simply Irlen syndrome (IS) has been described as symptoms of poor reading ability due to poor color matching and distorted graphic images. Individuals with this syndrome are considered slow, ineffective readers with low comprehension and visual fatigue. It is still uncertain whether the disease pathophysiology is an independent entity or part of the dyslexia spectrum. Nevertheless, treatments with lenses and colored filters have been proposed to alleviate the effect of the luminous contrast and improve patients’ reading performance. However, no evidence of treatment effectiveness has been achieved.

Objective: The aim of the present study was to obtain evidence about IS etiology, diagnosis and intervention efficacy.

Methods: A systematic review was performed covering the available studies on IS, assessing the available data according to their level of evidence, focusing on diagnostic tools, proposed interventions and related outcomes.

Results: The data showed high heterogeneity among studies, and lack of evidence on the existence of IS and treatment effectiveness.

Conclusion: The syndrome as described, as well as its treatments, require further strong evidence.

Keywords: Reading disorders; systematic review; evidence-based medicine; meares-irlen syndrome; colored lenses

Reference	Population		Study type	Diagnostic tool	Intervention	Main findings	Level of evidence
Reference	Population	Comparison group	Study type	Diagnostic tool	Intervention	Main findings	Level of evidence
O'Connor et al. 1990¹⁴	92 Children	Non-scotopic	CC	IDPS NARA FRI	PCOF DCOF	More visual comfort. Gained reading rate. Filter improved reading.	3
Scheiman et al. 1990¹⁵	Varied (age 10 to 49) n = 39	No control	CH	IDPS		More visual comfort. Gained reading rate. Filter improved reading.	4
Blaskey et al. 1990¹⁶	Varied (age 9 to 51) 12 male; 18 female	Non-scotopic	CCH	IDPS	IF	Self-declared more comfort. No gain in reading. Irlen filter group showed no significant gains.	4
Robinson, Conway 1990¹⁷	Varied (age 9 to 15) 33 males, 11 female	No control	CH	IDPS NARA SPAS	IF	Improvements on Irlen tests. No improvements on NARA and SPAS. Filter improved reading accuracy and comprehension, but not rate.	4
Martin et al. 1993¹⁸	7th graders n = 60	Normal readers	CCH	LILP NARA RPM NWT	IL/COF	No difference among groups. No gain in reading. No improvement with IL/COF.	4
Carrol et al. 1994¹⁹	Varied (age 10 to 20) n = 64	23 normal readers	CC	IDPS	Dark adaptation	No difference among groups. Inconclusive.	4
Evans et al. 1994²⁰	Varied (mean age 22; age 7 to 12) n = 82	11 normal readers	CC	PGT SRVST	COF	No difference with lenses. No differences in PGT among groups.	4
				NARA		Borderline significance supporting lenses.
Lopez et al. 1994²¹	Varied (children) 39	15 with “academic problems”	CC	ISSST	PCOF	No difference in PCOF users. No difference in academic performance. More research needed.	4
Sawyer et al. 1994²²	Varied (age 7 to 15) n = 271	86 children without referred reading problems	CC	SRTa	PCOF	Differences inside the instrument variation. No improvement in reading. Very low effect; other refractive problems as the cause; more investigation needed.	4
Wilkins et al. 1994²³	Varied (age 9 to 15) n = 37	Children with reported failing in reading, with and without lenses.	PCT	ISSST NARA	Intuitive Colorimeter®	No differences on NARA and other symptoms evaluated. No gain in reading. Lenses ameliorate symptoms of IS.	2
Evans et al. 1995²⁴	Children aged 12 n = 42	26 nonresponsive to COF	CC	ISSST SRTb NARA PGT	Intuitive Colorimeter®	No differences on NARA or symptoms. No gain in reading. Suggests caution on data interpretation due to high similarity among case and control groups.	4
	Adult and children			Interview		No differences on WRAT-R.
Spafford et al. 1995²⁵	4 children, 4 adults	8 matched controls	CC	WRAT-R	COF	Lens color not critical for reading. Inconclusive; use of any unproven therapy could delay appropriate treatment.	4
Evans et al. 1996²⁶	Reports on sample from previous study (25)	Participants report failing in reading, with/ without lenses.	CC	ISSST PGT Optometrics	COF	No difference in pattern glare and IS. Ocular motor anomalies correlate to IS. Method psychophysically primitive; optometric anomalies are priority in treatment.	4
Ciuffreda et al. 1997²⁷	Adults (age 18 to 39) 2 males; 6 females	No	OB/CR	LILP	COF	No positive effect on steady-state accommodation. No improvement on accuracy; participants in fact needed other vision intervention.	4
Evans et al 1999²⁸	Varied (age 4 to 73) N=323	No	RP/EP	ISSST IO IC	PCOF	Patient perception of improvement. 73% still wearing tinted lenses 1,5 yrs after.	4
Robinson, Foreman 1999²⁹	Children (age 9 to 13) n = 113	35 controls with reading problems	PCT	ISSST/LILP NARA	IL	No difference among groups. No modification related to other groups. No improvements at all.	2
Robinson, Foreman 1999³⁰	Same as previous (32) n = 88	28 controls from previous study (32)	PCT	ISSST/LILP NARA	IL	Statistical difference among selected groups. Improvements on some tasks.	2
Robinson et al 2000³¹	Varied (age 9 to 13) n = 158	125 referred 33 screening	PP	ISSST IS	-	84% of parents with IS No difference among groups Prevalence of symptoms on males	4
Bouldoukian et al. 2002³²	Varied (age 7 to 40) n = 33	With/without overlay	CC	IO WRRT	IO	Increased reading rate due to IO. Increased rate due to practice on same test. IO improved rate of reading. No placebo effect.	2
Evans, Joseph 2002³³	University students n = 113	13 participants without complaints	CC	IO WRRT	IO	More than 90% was 3,8% faster with IO. 21 participants stated that IO worsened perception. One-third of the sample shows benefit on reading (>5%) with colored lenses. Prevalence in adults equal in children.	4
Scott et al. 2002³⁴	Children (age 10 to 12) n = 94	63 without IS criterion	CC	IO, WRRT, LRT	IO	No difference among groups with and without IO. Supports the beneficial effects of IO.	4
	Children					No significant difference among groups; no increase in reading speed.
Northway, 2003³⁵	(age 9 to 15) n = 64	With/without lenses	OB/RP	IO, WRRT, DEM	IO	Improvement only on WRRT, not DEM. Visual symptomatic children found a preferred colored overlay of benefit.	4
Waldie, Wilkins, 2004³⁶	Children (age mean = 9.4) n = 23	-	OB	IO	IO	No significant difference among groups	4
Kriss, Evans, 2005³⁷	Children (age 7 to 12) n = 64 dyslexic	32 dyslexic; with / without IO	CC with 2x2 mixed factorial	IO, WRRT	IO	Control group w. higher scores in WRRT; 34% of dyslexic group up to 8% faster on WRRT with IO. IS affected normal readers. Although no significant difference in prevalence, more IS in dyslexic children.	4
Hollis, Allen, 2006³⁸	Adults (age 18 to 58) n = 58	-	OB/PP	IO WRRT PGT	IO	No benefit of IO for normal. Self reported symptom. Reading speed test recommended.	4
Riddel et al. 2006³⁹	Children (age 9 to 16) 10 (6 male; 4 female)	-	OB/CS	Previous IO users; VEP	IO	No significant differences among groups. No objective VEP differences can be measured in all children who claim benefit from the use of colored lenses.	4
Kruk et al. 2008⁴⁰	Children (age 9 to 10) n = 36	18 non-dyslexic	OB/PP	IRPS, LILP, WRAT	No intervention	No difference among normal readers and dyslexic. IS diagnosis was not an indicator of visual deficit subtype of dyslexia. No relationship between IS and reading performance.	4
	Children					NARA and SDMT improved in all groups.
	(age 7 to 11)					IDPS improved in placebo and experimental, and decreased in control.
Mitchell et al. 2008¹⁰.	n = 49 (35 male, 14 female)	With/without lenses	PCT	IDPS, NARA, SDMT, IC	IO	No difference among placebo and experimental groups.	2
						Clear definition of visuoperceptual reading disabilities impaired the possible conclusion and experimental design.
Nichols et al. 2009⁴¹	University students (mean age 23.4) n = 74 (7 male)	-	OB/PP	IO, WRRT, LADS	-	24% revealed IS. LADS occurred within IS. More research is needed.	4
	Adults					No improvement in reading.
Taub et al. 2009⁴²	N = 60	No referred symptoms of IS	OB/PP	Visagraph®	Colored lenses	No difference among groups. The IS symptoms were related to binocular/accommodative vision disorder.	4
Ritchie et al. 2011⁴³	Children (primary school) n = 75	-	OB/PP	LILT, WRRT, MMSE, GORT	IO	No gain in reading. No difference among groups for all tests. More orthoptic problem in IS group.	3
Vidal-López 2011⁴⁴	Secondary students (mean age 12) n = 54 (28 males)	27 paired individuals without IS	CC	PGT, IO, ISSST, PROLEC, SI, VS-SDT	IO	No differences with IO users. Attributional bias. Did not support the visual stress theory. Suggested strong motivational effects.	3
Ritchie et al. 2012⁴⁵	IS children (mean age 9) n = 18	10 non-IS	CC/CH (1yr)	WRRT, MMSE, GORT	IO	No difference among groups. No improvements with IO after 1yr. No benefits to reading. No effects in short or long term.	4
Chang et al. 2014⁴⁶	IS students (age 8 to 34) n = 34	11 dyslexic	CC	Not specified	IO Korea	Improvement needed on IS diagnosis. Lenses efficacy should be measured. Objectively testing for the syndrome. Further studies required.	4
Kim et al. 2015⁴⁷	Varied (age 13 to 41) n = 15	-	OB/PP	Self-reported IS	IO	Brain reacts different with and without lenses. Temporal regions activate after lenses.	4
Loew et al. 2015⁴⁸	Non-clinical samples (age 21 to 60) n = 24 (9 males, 15 females)	With/without lenses.	OB	Self-reported; WRRT; PROLEC; IO	Tinted lenses	No differences in reading speeds among participants with and without lenses. Fluorescent lighting can affect readers at all levels of proficiency.	4
Alanazi et al. 2016⁴⁹	Varied (age 18 to 30) n = 450	Female medical students	EP	Self-reported	Not defined	2% dyslexic 6% IS 33% dyslexic and IS	4
Garcia et al. 2017⁵⁰	Children (age 9 to 12) n = 68 (36 male, 32 female)	-	OB/PP	IRPS/OO, WRRT	ISOs	No significant gain in reading. 9 individuals reported 6% increase in reading speed on WRRT. Filters improved reading rate.	4

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[TFN1] IDPS: Irlen Differential Perceptual Schedule®, ISSST: Irlen Scotopic Sensitivity Screening Test®; IRPS: Irlen Reading Perceptual Scale®; IRPS/OO: IRPS Optimum Overlay®; ISOs: Irlen Spectral Overlays set®; LILP: Licensed Irlen Lens Practitioner; IO: Intuitive Overlays®; IC: Intuitive Colorimeter®; PGT: Pattern Glare Test; WRRG: Wilkins Rate of Reading Test; NARA: Neale Analysis of Reading Ability; SPAS: Students’ Perception of Ability Scale; FRI: Formal Reading Inventory; RPM: Raven's Progressive Matrices; NWT: Nonsense Word Test; SRVST: Simulated Reading Visual Search Test; SRTa: Salford Reading Test; SRTb: Suffolk Reading Test; WRAT-R: Wide Range Achievement Test-Revised; AIRA: Aston Index Reading Age; LRT: London Reading Test; DEM: Developmental Eye Movement test; VEP: Visual Evoked Potential; SDMT: Symbol Digit Modalities Test; Visagraph®; MMSE: Mini-Mental State Examination; GORT: Gray Oral Reading Test; PROLEC®; SI: Stress Inductor; VS-SDT: Visual Stimuli based on Signal Detection Theory; DRT: Dyslexia Research Trust UK; COF: Colored Overlay Filters; PCOF: Preferred Colored Overlay Filter; DCOF: Different-Colored Overlay Filters; IF: Irlen Filters; IL/COF: Irlen Filters/Colored Overlay Filters; IO: Intuitive Overlays®; CC: Case-Control; RCT: Randomized Control Trial; PCT: Placebo Controlled Trial; NRCC: Non-Randomized Controlled Cohort; CH: Cohort; CCH: Controlled Cohort; OB: Observational study; PP: Prospective; RP: Retrospective; EP: Epidemiologic; CR: Case report; CS: Case series; PL: Previous use of Irlen (or colored) lenses; IIP: Irlen Institute Patient.