Sustained fixation induced changes in phoria and convergence peak velocity.

<h4>Purpose</h4>This study sought to investigate the influence of phoria adaptation on convergence peak velocity from responses located at different initial vergence positions.<h4>Methods</h4>Symmetrical 4° convergence step responses and near dissociated phoria (measured at 4...

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Autores principales:	Eun H Kim, Vincent R Vicci, Sang J Han, Tara L Alvarez
Formato:	article
Lenguaje:	EN
Publicado:	Public Library of Science (PLoS) 2011
Materias:	Medicine R Science Q
Acceso en línea:	https://doaj.org/article/0d5c0b28b85b499098d0b5694fc5521d
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spelling	oai:doaj.org-article:0d5c0b28b85b499098d0b5694fc5521d2021-11-18T06:51:47ZSustained fixation induced changes in phoria and convergence peak velocity.1932-620310.1371/journal.pone.0020883https://doaj.org/article/0d5c0b28b85b499098d0b5694fc5521d2011-01-01T00:00:00Zhttps://www.ncbi.nlm.nih.gov/pmc/articles/pmid/21698110/?tool=EBIhttps://doaj.org/toc/1932-6203<h4>Purpose</h4>This study sought to investigate the influence of phoria adaptation on convergence peak velocity from responses located at different initial vergence positions.<h4>Methods</h4>Symmetrical 4° convergence step responses and near dissociated phoria (measured at 40 cm from the subject's midline) were recorded from six subjects with normal binocular vision using an infrared limbus tracking system with a haploscope. Two different sustained fixations (1° and 16° convergent rotation along the subject's midline) were used to study whether phoria had an influence on the peak velocity of convergence responses located at two initial vergence positions (1° or 'far' steps and 12° or 'near' steps).<h4>Results</h4>Phoria was significantly adapted after a sustained fixation task at near (16°) and far (1°) (p<0.002). A repeated measures ANOVA showed that convergence far steps were significantly faster than the near steps (p<0.03). When comparing convergence steps with the same initial vergence position, steps measured after near phoria adaptation were faster than responses after far adaptation (p<0.02). A regression analysis demonstrated that the change in phoria and the change in convergence peak velocity were significantly correlated for the far convergence steps (r = 0.97, p = 0.001). A weaker correlation was observed for the near convergence steps (r = 0.59, p = 0.20).<h4>Conclusion</h4>As a result of sustained fixation, phoria was adapted and the peak velocity of the near and far convergence steps was modified. This study has clinical considerations since prisms, which evoke phoria adaptation, can be prescribed to help alleviate visual discomfort. Future investigations should include a systematic study of how prisms may influence convergence and divergence eye movements for those prescribed with prisms within their spectacles.Eun H KimVincent R VicciSang J HanTara L AlvarezPublic Library of Science (PLoS)articleMedicineRScienceQENPLoS ONE, Vol 6, Iss 6, p e20883 (2011)
institution	DOAJ
collection	DOAJ
language	EN
topic	Medicine R Science Q
spellingShingle	Medicine R Science Q Eun H Kim Vincent R Vicci Sang J Han Tara L Alvarez Sustained fixation induced changes in phoria and convergence peak velocity.
description	<h4>Purpose</h4>This study sought to investigate the influence of phoria adaptation on convergence peak velocity from responses located at different initial vergence positions.<h4>Methods</h4>Symmetrical 4° convergence step responses and near dissociated phoria (measured at 40 cm from the subject's midline) were recorded from six subjects with normal binocular vision using an infrared limbus tracking system with a haploscope. Two different sustained fixations (1° and 16° convergent rotation along the subject's midline) were used to study whether phoria had an influence on the peak velocity of convergence responses located at two initial vergence positions (1° or 'far' steps and 12° or 'near' steps).<h4>Results</h4>Phoria was significantly adapted after a sustained fixation task at near (16°) and far (1°) (p<0.002). A repeated measures ANOVA showed that convergence far steps were significantly faster than the near steps (p<0.03). When comparing convergence steps with the same initial vergence position, steps measured after near phoria adaptation were faster than responses after far adaptation (p<0.02). A regression analysis demonstrated that the change in phoria and the change in convergence peak velocity were significantly correlated for the far convergence steps (r = 0.97, p = 0.001). A weaker correlation was observed for the near convergence steps (r = 0.59, p = 0.20).<h4>Conclusion</h4>As a result of sustained fixation, phoria was adapted and the peak velocity of the near and far convergence steps was modified. This study has clinical considerations since prisms, which evoke phoria adaptation, can be prescribed to help alleviate visual discomfort. Future investigations should include a systematic study of how prisms may influence convergence and divergence eye movements for those prescribed with prisms within their spectacles.
format	article
author	Eun H Kim Vincent R Vicci Sang J Han Tara L Alvarez
author_facet	Eun H Kim Vincent R Vicci Sang J Han Tara L Alvarez
author_sort	Eun H Kim
title	Sustained fixation induced changes in phoria and convergence peak velocity.
title_short	Sustained fixation induced changes in phoria and convergence peak velocity.
title_full	Sustained fixation induced changes in phoria and convergence peak velocity.
title_fullStr	Sustained fixation induced changes in phoria and convergence peak velocity.
title_full_unstemmed	Sustained fixation induced changes in phoria and convergence peak velocity.
title_sort	sustained fixation induced changes in phoria and convergence peak velocity.
publisher	Public Library of Science (PLoS)
publishDate	2011
url	https://doaj.org/article/0d5c0b28b85b499098d0b5694fc5521d
work_keys_str_mv	AT eunhkim sustainedfixationinducedchangesinphoriaandconvergencepeakvelocity AT vincentrvicci sustainedfixationinducedchangesinphoriaandconvergencepeakvelocity AT sangjhan sustainedfixationinducedchangesinphoriaandconvergencepeakvelocity AT taralalvarez sustainedfixationinducedchangesinphoriaandconvergencepeakvelocity
_version_	1718424271062040576

Sustained fixation induced changes in phoria and convergence peak velocity.

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