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Crowding in children with a visual impairment.


- candidate number8505
- NTR NumberNTR2537
- ISRCTNISRCTN wordt niet meer aangevraagd.
- Date ISRCTN created
- date ISRCTN requested
- Date Registered NTR28-sep-2010
- Secondary IDsNL26835.091.10 CCMO
- Public TitleCrowding in children with a visual impairment.
- Scientific TitleCrowding in children with a visual impairment: The effect of magnifier use on near visual acuity.
- ACRONYM
- hypothesis1. Children with a visual impairment experience more crowding than normally sighted children;
2. A magnifier reduces crowding effects by enlarging inter symbol space.
- Healt Condition(s) or Problem(s) studiedVisual impairment
- Inclusion criteria1. Age 3 to 8 years;
2. Normative developmental level;
3. Intact peripheral visual field;
4. Birth at term.
- Exclusion criteria1. Small visual field;
2. Multiple handicaps;
3. Prematurity.
- mec approval receivedyes
- multicenter trialyes
- randomisedno
- groupParallel
- Type2 or more arms, non-randomized
- Studytypeintervention
- planned startdate 1-mei-2010
- planned closingdate1-mrt-2013
- Target number of participants240
- InterventionsWe will measure crowding influences by comparing test performance by using a 1.8x magnifier vs enlarged test material (1.8x enlarged). In the next year, a crowding training will be developed and evaluated in 2012.
- Primary outcome1. Differences in crowding between normally sighted and visually impaired children;
2. Difference between magnifier and enlargement in visually impaired children;
3. Reduction of crowding after following a crowding training.
- Secondary outcomeWhich factors play an important role in crowding (eye movements, visual attention, optimal inter symbol spacing)?
- TimepointsN/A
- Trial web siteN/A
- statusstopped: trial finished
- CONTACT FOR PUBLIC QUERIESMSc Bianca Huurneman
- CONTACT for SCIENTIFIC QUERIESDr. F.N. Boonstra
- Sponsor/Initiator Bartiméus
- Funding
(Source(s) of Monetary or Material Support)
ZON-MW, The Netherlands Organization for Health Research and Development
- PublicationsN/A
- Brief summaryCrowding is a phenomenon in which symbols are less accurately identified in the proximity of other symbols. This phenomenon is present in everyone at some point, but normally disappears between the age of five to seven and is then no longer disturbing. Children with a visual impairment experience more crowding than normally sighted children. Research has shown that an impressive number of adults with a visual impairment still experience disturbing amounts of crowding. Crowding has a big influence on reading and learning to read. Children with a visual impairment have more problems with reading and learning to read than normally sighted children. They show poorer reading speed, which indicates that the process of decoding the letter symbols takes more time.
The visual system is more capable of identifying symbols when they are larger and the space between symbols is larger. A magnifier also reduces the amount of symbols in the field of view. The combination of these two factors suggests that a child who experiences difficulties in identifying closely-spaced symbols because of crowding will benifit from the use of a magnifier.
The recent study proposal is focussed on exploring the difference in crowding between normally sighted and visually impaired children and effects of the use of a magnifier to reduce crowding.
- Main changes (audit trail)
- RECORD28-sep-2010 - 22-mei-2015


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