SynthesisBMC ophthalmology2012
A systematic review on 'Foveal Crowding' in visually impaired children and perceptual learning as a method to reduce Crowding.
Synthesis in BMC ophthalmology, 2012. The graph could read no effect estimate from its abstract, so it casts no vote on the map. It is linked to trial NCT03505606 (Examination of New Visual Acuity and Clinical Crowding Tests for Better Detection of Amblyopia), which is not on this map. Cited by 16 papers.
What it found
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The abstract states no effect estimate the extractor could read, or names no intervention and outcome on the map, so this paper lights no cell and moves no belief. It is still indexed, cited and linked below.
The trial behind it
Trials whose registry record cites this paper, or whose number appears in the abstract. A trial that started after this paper was published is citing it as background, not reporting it.
Examination of New Visual Acuity and Clinical Crowding Tests for Better Detection of Amblyopia
Who cites it
16 citing papers in PubMed, 40 citations in OpenAlex.
- The development of visual acuity and crowding reveals the slow fine-tuning of foveal vision.Scientific reports · 2025Article
- Early years examination to identify suspect cerebral visual impairment (EYE-CVI): a feasibility study.BMJ open ophthalmology · 2025Article
- Crowding under scotopic and photopic vision in albino and normal-sighted participants.Scientific reports · 2024Article
- A history of visual acuity testing and optotypes.Eye (London, England) · 2024Review
- Current perspective: Cerebral visual impairment-The impending doom.Indian journal of ophthalmology · 2023Article
- Visual Function and Neuropsychological Profiling of Idiopathic Infantile Nystagmus.Brain sciences · 2023Article
- Motion adaptation improves acuity (but perceived size doesn't matter).Journal of vision · 2022Article
- Visual Function and Neuropsychological Profile in Children with Cerebral Visual Impairment.Children (Basel, Switzerland) · 2022Article
- The Multidisciplinary Guidelines for Diagnosis and Referral in Cerebral Visual Impairment.Frontiers in human neuroscience · 2022Article
- The Developmental Eye Movement Test as a Diagnostic Aid in Cerebral Visual Impairment.Frontiers in human neuroscience · 2021Article
- Higher Visual Function Deficits in Children With Cerebral Visual Impairment and Good Visual Acuity.Frontiers in human neuroscience · 2021Article
- Monocular and Binocular Temporal Visual Perception of Infantile Nystagmus.Scientific reports · 2020Article
- Crowding, grouping, and object recognition: A matter of appearance.Journal of vision · 2015Article
- The effect of aging on crowded letter recognition in the peripheral visual field.Investigative ophthalmology & visual science · 2014Article
- Crowded task performance in visually impaired children: magnifier versus large print.Graefe's archive for clinical and experimental ophthalmology = Albrecht von Graefes Archiv fur klinische und experimentelle Ophthalmologie · 2013Article
- Learning to identify crowded letters: does the learning depend on the frequency of training?Vision research · 2013Article
Corrections and comments
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Authors and funding
5 authors at 2 institutions in 1 country.
Funding
No grant is acknowledged in the PubMed record.
Abstract
backgroundThis systematic review gives an overview of foveal crowding (the inability to recognize objects due to surrounding nearby contours in foveal vision) and possible interventions. Foveal crowding can have a major effect on reading rate and deciphering small pieces of information from busy visual scenes. Three specific groups experience more foveal crowding than adults with normal vision (NV): 1) children with NV, 2) visually impaired (VI) children and adults and 3) children with cerebral visual impairment (CVI). The extent and magnitude of foveal crowding as well as interventions aimed at reducing crowding were investigated in this review. The twofold goal of this review is : [A] to compare foveal crowding in children with NV, VI children and adults and CVI children and [B] to compare interventions to reduce crowding.
methodsThree electronic databases were used to conduct the literature search: PubMed, PsycINFO (Ovid), and Cochrane. Additional studies were identified by contacting experts. Search terms included visual perception, contour interaction, crowding, crowded, and contour interactions.
resultsChildren with normal vision show an extent of contour interaction over an area 1.5-3× as large as that seen in adults NV. The magnitude of contour interaction normally ranges between 1-2 lines on an acuity chart and this magnitude is even larger when stimuli are arranged in a circular configuration. Adults with congenital nystagmus (CN) show interaction areas that are 2× larger than those seen adults with NV. The magnitude of the crowding effect is also 2× as large in individuals with CN as in individuals with NV. Finally, children with CVI experience a magnitude of the crowding effect that is 3× the size of that experienced by adults with NV.
conclusionsThe methodological heterogeneity, the diversity in paradigms used to measure crowding, made it impossible to conduct a meta-analysis. This is the first systematic review to compare crowding ratios and it shows that charts with 50% interoptotype spacing were most sensitive to capture crowding effects. The groups that showed the largest crowding effects were individuals with CN, VI adults with central scotomas and children with CVI. Perceptual Learning seems to be a promising technique to reduce excessive foveal crowding effects.
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Registered trials
Read under generation 80e0d062 · epoch 390. Bibliography from PubMed, PubMed Central and OpenAlex; grants from NIH RePORTER; trial links from ClinicalTrials.gov; estimates, votes and beliefs from the OpenQuestion graph.