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Influence of different types of astigmatism on visual acuity

PURPOSE: To investigate the change in visual acuity (VA) produced by different types of astigmatism (on the basis of the refractive power and position of the principal meridians) on normal accommodating eyes. METHODS: The lens induced method was employed to simulate a set of 28 astigmatic blur condi...

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Autores principales: Remón, Laura, Monsoriu, Juan A., Furlan, Walter D.
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Elsevier 2017
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5484781/
https://www.ncbi.nlm.nih.gov/pubmed/27639497
http://dx.doi.org/10.1016/j.optom.2016.07.003
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author Remón, Laura
Monsoriu, Juan A.
Furlan, Walter D.
author_facet Remón, Laura
Monsoriu, Juan A.
Furlan, Walter D.
author_sort Remón, Laura
collection PubMed
description PURPOSE: To investigate the change in visual acuity (VA) produced by different types of astigmatism (on the basis of the refractive power and position of the principal meridians) on normal accommodating eyes. METHODS: The lens induced method was employed to simulate a set of 28 astigmatic blur conditions on different healthy emmetropic eyes. Additionally, 24 values of spherical defocus were also simulated on the same eyes for comparison. VA was measured in each case and the results, expressed in logMAR units, were represented against of the modulus of the dioptric power vector (blur strength). RESULTS: LogMAR VA varies in a linear fashion with increasing astigmatic blur, being the slope of the line dependent on the accommodative demand in each type of astigmatism. However, in each case, we found no statistically significant differences between the three axes investigated (0°, 45°, 90°). Non-statistically significant differences were found either for the VA achieved with spherical myopic defocus (MD) and mixed astigmatism (MA). VA with simple hyperopic astigmatism (SHA) was higher than with simple myopic astigmatism (SMA), however, in this case non conclusive results were obtained in terms of statistical significance. The VA achieved with imposed compound hyperopic astigmatism (CHA) was highly influenced by the eye's accommodative response. CONCLUSIONS: VA is correlated with the blur strength in a different way for each type of astigmatism, depending on the accommodative demand. VA is better when one of the focal lines lie on the retina irrespective of the axis orientation; accommodation favors this situation.
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spelling pubmed-54847812017-07-10 Influence of different types of astigmatism on visual acuity Remón, Laura Monsoriu, Juan A. Furlan, Walter D. J Optom Original Article PURPOSE: To investigate the change in visual acuity (VA) produced by different types of astigmatism (on the basis of the refractive power and position of the principal meridians) on normal accommodating eyes. METHODS: The lens induced method was employed to simulate a set of 28 astigmatic blur conditions on different healthy emmetropic eyes. Additionally, 24 values of spherical defocus were also simulated on the same eyes for comparison. VA was measured in each case and the results, expressed in logMAR units, were represented against of the modulus of the dioptric power vector (blur strength). RESULTS: LogMAR VA varies in a linear fashion with increasing astigmatic blur, being the slope of the line dependent on the accommodative demand in each type of astigmatism. However, in each case, we found no statistically significant differences between the three axes investigated (0°, 45°, 90°). Non-statistically significant differences were found either for the VA achieved with spherical myopic defocus (MD) and mixed astigmatism (MA). VA with simple hyperopic astigmatism (SHA) was higher than with simple myopic astigmatism (SMA), however, in this case non conclusive results were obtained in terms of statistical significance. The VA achieved with imposed compound hyperopic astigmatism (CHA) was highly influenced by the eye's accommodative response. CONCLUSIONS: VA is correlated with the blur strength in a different way for each type of astigmatism, depending on the accommodative demand. VA is better when one of the focal lines lie on the retina irrespective of the axis orientation; accommodation favors this situation. Elsevier 2017 2016-09-14 /pmc/articles/PMC5484781/ /pubmed/27639497 http://dx.doi.org/10.1016/j.optom.2016.07.003 Text en © 2016 Spanish General Council of Optometry. Published by Elsevier Espa˜na, S.L.U. http://creativecommons.org/licenses/by-nc-nd/4.0/ This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).
spellingShingle Original Article
Remón, Laura
Monsoriu, Juan A.
Furlan, Walter D.
Influence of different types of astigmatism on visual acuity
title Influence of different types of astigmatism on visual acuity
title_full Influence of different types of astigmatism on visual acuity
title_fullStr Influence of different types of astigmatism on visual acuity
title_full_unstemmed Influence of different types of astigmatism on visual acuity
title_short Influence of different types of astigmatism on visual acuity
title_sort influence of different types of astigmatism on visual acuity
topic Original Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5484781/
https://www.ncbi.nlm.nih.gov/pubmed/27639497
http://dx.doi.org/10.1016/j.optom.2016.07.003
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