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Variability of the accommodation response in early onset myopia.
Optom Vis Sci. 2008 Jan; 85(1):37-48.OV

Abstract

PURPOSE

Hyperopic retinal defocus (blur) is thought to be a cause of myopia. If the retinal image of an object is not clearly focused, the resulting blur is thought to cause the continuing lengthening of the eyeball during development causing a permanent refractive error. Both lag of accommodation, especially for near targets, and greater variability in the accommodative response, have been suggested as causes of increased hyperopic retinal blur. Previous studies of lag of accommodation show variable findings. In comparison, greater variability in the accommodative response has been demonstrated in adults with late onset myopia but has not been tested in children. This study looked at the lag and variability of accommodation in children with early onset myopia.

METHODS

Twenty-one myopic and 18 emmetropic children were tested. Dynamic measures of accommodation and pupil size were made using eccentric photorefraction (PowerRefractor) while children viewed targets set at three different accommodative demands (0.25, 2, and 4 D).

RESULTS

We found no difference in accommodative lag between groups. However, the accommodative response was more variable in the myopes than emmetropes when viewing both the near (4 D) and far (0.25 D) targets. Since pupil size and variability also varied, we analyzed the data to determine whether this could account for the inter-group differences in accommodation variability. Variation in these factors was not found to be sufficient to explain these differences. Changes in the accommodative response variability with target distance were similar to patterns reported previously in adult emmetropes and late onset myopes.

CONCLUSIONS

Children with early onset myopia demonstrate greater accommodative variability than emmetropic children, and have similar patterns of response to adult late onset myopes. This increased variability could result in an increase in retinal blur for both near and far targets. The role of accommodative variability in the etiology of myopia is discussed.

Authors+Show Affiliations

Department of Optometry and Visual Science, Buskerud University College, Kongsberg, Norway. trine.langaas@hibu.noNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Comparative Study
Journal Article
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

18174839

Citation

Langaas, Trine, et al. "Variability of the Accommodation Response in Early Onset Myopia." Optometry and Vision Science : Official Publication of the American Academy of Optometry, vol. 85, no. 1, 2008, pp. 37-48.
Langaas T, Riddell PM, Svarverud E, et al. Variability of the accommodation response in early onset myopia. Optom Vis Sci. 2008;85(1):37-48.
Langaas, T., Riddell, P. M., Svarverud, E., Ystenaes, A. E., Langeggen, I., & Bruenech, J. R. (2008). Variability of the accommodation response in early onset myopia. Optometry and Vision Science : Official Publication of the American Academy of Optometry, 85(1), 37-48. https://doi.org/10.1097/OPX.0b013e31815ed6e9
Langaas T, et al. Variability of the Accommodation Response in Early Onset Myopia. Optom Vis Sci. 2008;85(1):37-48. PubMed PMID: 18174839.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Variability of the accommodation response in early onset myopia. AU - Langaas,Trine, AU - Riddell,Patricia M, AU - Svarverud,Ellen, AU - Ystenaes,Ann E, AU - Langeggen,Irene, AU - Bruenech,Jan Richard, PY - 2008/1/5/pubmed PY - 2008/3/5/medline PY - 2008/1/5/entrez SP - 37 EP - 48 JF - Optometry and vision science : official publication of the American Academy of Optometry JO - Optom Vis Sci VL - 85 IS - 1 N2 - PURPOSE: Hyperopic retinal defocus (blur) is thought to be a cause of myopia. If the retinal image of an object is not clearly focused, the resulting blur is thought to cause the continuing lengthening of the eyeball during development causing a permanent refractive error. Both lag of accommodation, especially for near targets, and greater variability in the accommodative response, have been suggested as causes of increased hyperopic retinal blur. Previous studies of lag of accommodation show variable findings. In comparison, greater variability in the accommodative response has been demonstrated in adults with late onset myopia but has not been tested in children. This study looked at the lag and variability of accommodation in children with early onset myopia. METHODS: Twenty-one myopic and 18 emmetropic children were tested. Dynamic measures of accommodation and pupil size were made using eccentric photorefraction (PowerRefractor) while children viewed targets set at three different accommodative demands (0.25, 2, and 4 D). RESULTS: We found no difference in accommodative lag between groups. However, the accommodative response was more variable in the myopes than emmetropes when viewing both the near (4 D) and far (0.25 D) targets. Since pupil size and variability also varied, we analyzed the data to determine whether this could account for the inter-group differences in accommodation variability. Variation in these factors was not found to be sufficient to explain these differences. Changes in the accommodative response variability with target distance were similar to patterns reported previously in adult emmetropes and late onset myopes. CONCLUSIONS: Children with early onset myopia demonstrate greater accommodative variability than emmetropic children, and have similar patterns of response to adult late onset myopes. This increased variability could result in an increase in retinal blur for both near and far targets. The role of accommodative variability in the etiology of myopia is discussed. SN - 1040-5488 UR - https://www.unboundmedicine.com/medline/citation/18174839/Variability_of_the_accommodation_response_in_early_onset_myopia_ L2 - http://dx.doi.org/10.1097/OPX.0b013e31815ed6e9 DB - PRIME DP - Unbound Medicine ER -