{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,4,2]],"date-time":"2026-04-02T19:12:02Z","timestamp":1775157122318,"version":"3.50.1"},"reference-count":34,"publisher":"Springer Science and Business Media LLC","issue":"1","license":[{"start":{"date-parts":[[2016,12,5]],"date-time":"2016-12-05T00:00:00Z","timestamp":1480896000000},"content-version":"vor","delay-in-days":0,"URL":"http:\/\/onlinelibrary.wiley.com\/termsAndConditions#vor"}],"funder":[{"DOI":"10.13039\/100000002","name":"National Institutes of Health","doi-asserted-by":"publisher","award":["R01 EY014460"],"award-info":[{"award-number":["R01 EY014460"]}],"id":[{"id":"10.13039\/100000002","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/100000002","name":"National Institutes of Health","doi-asserted-by":"publisher","award":["T35 EY013937"],"award-info":[{"award-number":["T35 EY013937"]}],"id":[{"id":"10.13039\/100000002","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/100000002","name":"National Institutes of Health","doi-asserted-by":"publisher","award":["P30 EY019008"],"award-info":[{"award-number":["P30 EY019008"]}],"id":[{"id":"10.13039\/100000002","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/100002089","name":"Fight for Sight","doi-asserted-by":"publisher","id":[{"id":"10.13039\/100002089","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":["onlinelibrary.wiley.com"],"crossmark-restriction":true},"short-container-title":["Ophthalmic Physiologic Optic"],"published-print":{"date-parts":[[2017,1]]},"abstract":"<jats:title>Abstract<\/jats:title>\n                  <jats:sec>\n                    <jats:title>Purpose<\/jats:title>\n                    <jats:p>Heterophoria is the misalignment of the eyes in monocular viewing and represents the accuracy of vergence driven by all classical cues except disparity. It is challenging to assess restless children using clinical cover tests, and phoria in early childhood is poorly understood. Here we used eye tracking to assess phoria as a function of viewing distance and target in adults and young children, with comparison to clinical cover tests.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Methods<\/jats:title>\n                    <jats:p>\n                      Purkinje image tracking (\n                      <jats:styled-content style=\"fixed-case\">MCS<\/jats:styled-content>\n                      PowerRefractor) was used to record eye alignment in adults (19\u201328 years,\n                      <jats:italic>N<\/jats:italic>\n                      = 24) and typically developing children (3\u20135 years,\n                      <jats:italic>N<\/jats:italic>\n                      = 24). Objective unilateral and alternating cover tests were performed using an infrared filter while participants viewed a pseudo\u2010randomised sequence of Lea symbols (0.18 log\n                      <jats:styled-content style=\"fixed-case\">MAR<\/jats:styled-content>\n                      ; Snellen: 20\/30 or 6\/9) and animated cartoon movies at distances of 40 cm, 1 m, and 6 m. For the unilateral cover test, a 10 s binocular period preceded and followed 30 s of occlusion of the right eye. For the alternating cover test, a 10 s binocular period preceded and followed alternate covering of right and left eyes for 3\u2010s each. Phoria was derived from the difference in weighted average binocular and monocular alignment. A masked prism\u2010neutralised clinical cover test was performed for each of the conditions for comparison.\n                    <\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Results<\/jats:title>\n                    <jats:p>\n                      Closer viewing distance resulted in greater exophoria for both children and adults (\n                      <jats:italic>p<\/jats:italic>\n                      &lt; 0.001). Phorias were similar for adults and children for each viewing distance and target, with mean differences of less than 2 prism dioptres (pd). Overall, the average PowerRefractor phorias (pooled across protocols) for adults were 1.3, 2.3 and 3.8 pd exophoria and for children were 0.1 pd esophoria, 0.94 and 3.8 pd exophoria for the 6 m, 1 m and 40 cm distances respectively. The corresponding clinical cover test values were 0.7, 1.9, and 4.1 pd exophoria for adults and 0, 1.5 and 3.3 pd exophoria for the children. Refractive states were also similar (\u22640.5 D difference) for viewing the Lea symbols or movie for any protocol tested.\n                    <\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Conclusions<\/jats:title>\n                    <jats:p>\n                      Phoria estimation can be challenging for a pre\u2010school child. These data suggest that by 3\u20135 years of age objective eye\u2010tracking measures in a typically developing group are adult\u2010like at the range of distances tested, and that use of an animated movie produces similar average results to a small optotype (0.18 log\n                      <jats:styled-content style=\"fixed-case\">MAR<\/jats:styled-content>\n                      ; Snellen 20\/30 or 6\/9).\n                    <\/jats:p>\n                  <\/jats:sec>","DOI":"10.1111\/opo.12342","type":"journal-article","created":{"date-parts":[[2016,12,5]],"date-time":"2016-12-05T22:46:48Z","timestamp":1480978008000},"page":"7-15","update-policy":"https:\/\/doi.org\/10.1002\/crossmark_policy","source":"Crossref","is-referenced-by-count":7,"title":["The heterophoria of 3\u20135 year old children as a function of viewing distance and target type"],"prefix":"10.1007","volume":"37","author":[{"given":"Mary E.","family":"Troyer","sequence":"first","affiliation":[{"name":"Indiana University School of Optometry Bloomington, Indiana USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Vidhyapriya","family":"Sreenivasan","sequence":"additional","affiliation":[{"name":"Indiana University School of Optometry Bloomington, Indiana USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"T. J.","family":"Peper","sequence":"additional","affiliation":[{"name":"Indiana University School of Optometry Bloomington, Indiana USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"T. Rowan","family":"Candy","sequence":"additional","affiliation":[{"name":"Indiana University School of Optometry Bloomington, Indiana USA"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"297","published-online":{"date-parts":[[2016,12,5]]},"reference":[{"key":"e_1_2_8_2_1","volume-title":"The Clinical Use of Prisms; and the Decentering of Lenses","author":"Maddox 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