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Vision and brain in adolescents with low birth weight
2009 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Premature birth and pregnancy to term, but with intrauterine growth restriction (often manifesting as birth small for gestational age, SGA, at term), both represent suboptimal environments for the developing infant brain and eyes. Very low birth weight (VLBW,

The aims of this study, which is part of large interdisciplinary follow up study also including cognitive, psychiatric, paediatric and motor evaluation, as well as cerebral MRI, was threefold: to examine differences in visual functions between adolescents with VLBW, or SGA at term, compared to an age matched control group to explore how detected impairments affect other functions (e.g. motor ability) to search for a cerebral correlate to the impaired visual functions, by using magnetic resonance diffusion tensor imaging (DTI).

The study shows that the VLBW group was more likely to have poor visual acuity, reduced contrast sensitivity, poor convergence, strabismus, nystagmus, anisometropia, a need for new glasses and to have started with glasses earlier than the control group. The SGA group had a slight increase in hypermetropia, but did otherwise not differ from the control group. However, none of the participants were blind or had visual acuity

Both the SGA and the VLBW group had increased risk for motor problems, but these were affected by visual ability only in the VLBW group. Risk for motor problems were reduced by 25 % by controlling for poor visual acuity, but group still remained a significant factor. Visual impairments may cause motor problems, but it is also possible that cerebral damage may be the cause of simultaneous visual and motor problems.

Finally, using DTI, a positive correlation between visual acuity and the microstructure of white matter (reflecting axonal “healthiness”) was demonstrated in the splenium part of the corpus callosum. This part of the brain is responsible for the transhemispherical relay of visual data, and is particularly prone to injury in prematurity. However, it has not been regarded as an important factor for visual acuity in prematurity before.

Premature infants are greatly at risk for perinatal cerebral injury, due to an extreme vulnerability of several cerebral systems at a crucial time, when development is particularly fast and comprehensive. This is combined with very poor ability to maintain homeostasis, causing them to suffer infections, hypoxia, unstable blood pressure, undernourishment, among others, all pathological conditions which affect the developing brain negatively.

This study confirms that adolescents with VLBW have an increased risk of visual problems. Cerebral injury probably plays a major part in causing them.

Abstract [no]

Syn og hjerne hos ungdommer med lav fødselsvekt.

Forhold i svangerskapet og rundt fødselen har betydning for hvor godt vi fungerer på en rekke områder senere i livet. Dette gjelder ikke minst synet. For å kartlegge hvordan det går med synet til barn som fødes meget for tidlig (de som veier under 1500 g ved fødsel) og barn som fødes til termin med lavere fødselsvekt enn det forventede på grunn av dårlig ernæring i svangerskapet, har vi undersøkt synet til 14-åringer i disse to gruppene. Ungdommer i samme alder født til termin med normal fødselsvekt utgjorde kontrollgruppe.

Deltagerne i studien ble undersøkt av øyelege og fysioterapeut, og hjernens anatomi ble undersøkt med MR.

Studien viser at det synsmessig kan gjøre stor forskjell mellom å veie mindre enn 1500 g ved fødselen og å være født til termin med normal fødselsvekt. I gruppen med for tidlig fødte ungdommer hadde nesten hver tredje dårligere syn enn det normale for alderen sammenlignet med bare 4 % i kontrollgruppen. Blant de premature var det flere som hadde nedsatt evne til å skjelne små forskjeller i kontrast, og det var også vanligere med skjeling og dårlig samsyn.

Det var ikke større forekomst av nærsynthet eller langsynthet blant de premature. Derimot var det noe vanligere å trenge nye briller i prematurgruppen (53 %) enn i kontrollgruppen (34 %).

Et oppløftende funn var at ingen av ungdommene var blind eller synshemmet etter Verdens Helseorganisasjons kriterier. Tenåringer i gruppen født til termin med lavere fødselsvekt enn det normale hadde ikke øket risiko for synsproblemer.

Både de premature og ungdommene født til termin med lav fødselsvekt hadde økt forekomst av motoriske vansker. Da vi sammenlignet syn og motoriske evner, fant vi en sammenheng i prematurgruppen, men ikke i gruppen født til termin med lav fødselsvekt.

Mange av disse problemene med syn og motorikk kan bero på skader i hjernen på grunn av den for tidlige fødselen. Vi sammenlignet hjernens anatomi med synsdata og fant at det i prematurgruppen var en sammenheng mellom syn og anatomisk struktur av den midtre hjernebjelken (”corpus callosum”) som knyter sammen de to hjernehalvdelene. Hjernebjelken er et område som er spesielt utsatt for skade hos premature, men det har tidligere ikke vært vist så tydelig at skade i dette området har betydning for synet. Dessuten fant vi en sammenheng mellom skade på andre deler av hjernens synsbaner og syn i prematurgruppen

Place, publisher, year, pages
Trondheim NTNU, 2009.
Series
Doktoravhandlinger ved NTNU, ISSN 1503-8181 ; 2009:198Dissertations at the Faculty of Medicine, ISSN 0805-7680 ; 408
Identifiers
urn:nbn:no:ntnu:diva-6612 (URN)978-82-471-1795-8 (printed ver.) (ISBN)oai:DiVA.org:ntnu-6612 (OAI)diva2:285913 (DiVA)
Public defence
2009-10-16, 00:00 (English)
Available from2010-01-13 Created:2010-01-13 Last updated:2011-10-03Bibliographically approved
List of papers
1. Visual acuity, contrast sensitivity, peripheral vision and refraction in low birthweight teenagers.
Open this publication in new window or tab >>Visual acuity, contrast sensitivity, peripheral vision and refraction in low birthweight teenagers.
2007 (English)In: Acta Ophthalmologica Scandinavica, ISSN 1395-3907, E-ISSN 1600-0420, Vol. 85, no 2, 157-64Article in journal (Refereed) Published
Abstract [en]

PURPOSE: To assess visual acuity (VA), contrast sensitivity, visual fields, refractive errors and use of correction in adolescents with very low birthweight (VLBW; birthweight < 1500 g) and adolescents born at term but small for gestational age (SGA; birthweight < 10th percentile) in a population-based study.

METHODS: Ophthalmological examination including VA, Vistech contrast sensitivity and Humphrey two-zone, 120-point perimetry was performed in 51 VLBW, 59 SGA and 77 control adolescents.

RESULTS: The VLBW adolescents had reduced VA, reduced contrast sensitivity, and were more often anisometropic compared with control adolescents. They had started wearing glasses earlier, but were not more likely to use correction as teenagers. However, they were more often undercorrected (for refractive status) than control adolescents. Hypermetropia was more common in the SGA group than in the control group, but otherwise the SGA group did not differ from the control group.

CONCLUSIONS: Being born SGA may be a risk factor for hypermetropia in adolescence. Prematurely born adolescents present lower VA and contrast sensitivity and are more prone to anisometropia than adolescents born at term. It may be noteworthy that a higher proportion of VLBW than control adolescents were undercorrected, despite the well known vulnerability of visual function associated with preterm birth.

Identifiers
urn:nbn:no:ntnu:diva-13927 (URN)10.1111/j.1600-0420.2006.00808.x (DOI)17305728 (PubMedID)
Available from2011-09-28 Created:2011-09-28 Last updated:2011-10-03Bibliographically approved
2. Eye movements and binocular function in low birthweight teenagers.
Open this publication in new window or tab >>Eye movements and binocular function in low birthweight teenagers.
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2008 (English)In: Acta ophthalmologica, ISSN 1755-3768, Vol. 86, no 3, 265-74Article in journal (Refereed) Published
Abstract [en]

PURPOSE: To assess eye movements and binocular function in 14-year-olds with very low birthweight (VLBW: birthweight </= 1500 g) and 14-year-olds born at term but small for gestational age (SGA: birthweight < 10th percentile) in a population-based study.

METHODS: Ophthalmological examinations including measurements of heterophoria/tropia, near point of convergence, accommodative amplitude, stereopsis, nystagmus, saccades and smooth pursuit were performed in 51 adolescents with VLBW, 58 adolescents born SGA and in a control group consisting of 75 subjects of the same age.

RESULTS: Latent or manifest strabismus, poor stereopsis, poor convergence and nystagmus were all more frequent in the VLBW group than in the control group. The VLBW group did not differ from the control group regarding accommodative amplitude or saccades and smooth pursuit. The SGA population did not differ from the control group in the measured variables.

CONCLUSIONS: Premature birth with VLBW affects binocular visual functions negatively in adolescence, whereas birth small for date at term does not appear to be a risk factor for impaired eye movements and binocular function.

Identifiers
urn:nbn:no:ntnu:diva-13926 (URN)10.1111/j.1600-0420.2007.01133.x (DOI)18221495 (PubMedID)
Available from2011-09-28 Created:2011-09-28 Last updated:2011-10-03Bibliographically approved
3. Do visual impairments affect risk of motor problems in preterm and term low birth weight adolescents?
Open this publication in new window or tab >>Do visual impairments affect risk of motor problems in preterm and term low birth weight adolescents?
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2009 (English)In: European journal of paediatric neurology, ISSN 1090-3798, E-ISSN 1532-2130, Vol. 13, no 1, 47-56Article in journal (Refereed) Published
Abstract [en]

Visual impairments influence motor problems in VLBW adolescents, whereas motor problems in SGA adolescents seem to be unaffected by visual impairments.

Identifiers
urn:nbn:no:ntnu:diva-11819 (URN)10.1016/j.ejpn.2008.02.009 (DOI)18430596 (PubMedID)
Note
The article is reprinted with kind permission from Elsevier, sciencedirect.comAvailable from2011-01-11 Created:2011-01-11 Last updated:2011-10-03Bibliographically approved
4. Corpus callosum—connecting visual acuity and white matter microstructure in prematurity
Open this publication in new window or tab >>Corpus callosum—connecting visual acuity and white matter microstructure in prematurity
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(English)Manuscript (preprint) (Other academic)
Identifiers
urn:nbn:no:ntnu:diva-13928 (URN)10.1016/j.visres.2011.08.002 (DOI)
Note
NOTICE: this is the author’s version of a work that was accepted for publication in "Vision Research". Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in PUBLICATION,VOL 51, ISSUE 18, 15 September 2011, Pages 2063-2070, DOI:10.1016/j.visres.2011.08.002 Available from2011-09-28 Created:2011-09-28 Last updated:2011-10-03Bibliographically approved

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