Phoria Testing Distance Effect on Measurement at Various Accommodation Levels

Alpern, Mathew

doi:10.1001/archopht.1955.00930020912014

Cited by 21 publications

(3 citation statements)

References 13 publications

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“…Maddox originally suggested that the phoria position represents the combined contributions of tonic, proximal and accommodative vergence activity. Thus, the phoria could be influenced by factors such as the content of the visual stimulus and its viewing distance, which both influence accommodation and proximal responses, or the method and time of dissociation when tonic adaptation can impact the phoria estimate . Other factors such as age and refractive error also play a role in determining its magnitude .…”

Section: Introductionmentioning

confidence: 99%

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The heterophoria of 3–5 year old children as a function of viewing distance and target type

Troyer

Sreenivasan

Peper

et al. 2016

Ophthalmic Physiologic Optic

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Purpose 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. Methods Purkinje image tracking (MCS PowerRefractor) was used to record eye alignment in adults (19–28 years, N = 24) and typically developing children (three to five years, N = 24). Objective unilateral and alternating cover tests were performed using an infrared filter while participants viewed a pseudo-randomised sequence of Lea symbols (0.18 logMAR; 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 second binocular period preceded and followed 30 seconds of occlusion of the right eye. For the alternating cover test, a 10 second binocular period preceded and followed alternate covering of right and left eyes for three seconds each. Phoria was derived from the difference in weighted average binocular and monocular alignment. A masked prism-neutralised clinical cover test was performed for each of the conditions for comparison. Results Closer viewing distance resulted in greater exophoria for both children and adults (p < 0.001). Phorias were similar for adults and children for each viewing distance and target, with mean differences of less than 2 prism dioptres or pd. Overall, the average PowerRefractor phorias in pd (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 (≤ 0.5 D) for viewing the Lea symbols or movie for any protocol tested. Conclusions Phoria estimation can be challenging for a pre-school child. These data suggest that by three to five years of age objective eye-tracking measures in a typically developing group are adult-like at the range of distances tested, and that use of an animated movie produces similar average results to a small optotype (0.18 logMAR; Snellen 20/30 or 6/9).

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Section: Introductionmentioning

confidence: 99%

“…Other factors such as age and refractive error also play a role in determining its magnitude . While the impact of these factors has been studied in adults and older children (e.g …”

Section: Introductionmentioning

confidence: 99%

The heterophoria of 3–5 year old children as a function of viewing distance and target type

Troyer

Sreenivasan

Peper

et al. 2016

Ophthalmic Physiologic Optic

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show abstract

“…A motor located on the right arm moved the target along the subject's line of sight to stimulate accommodation. The centre of rotation of the left arm was congruent with the centre of rotation of the left eye (estimated at 13 mm behind the corneal pole) . The left‐arm servomotor induced calibrated vergence disparities.…”

Section: Methodsmentioning

confidence: 86%

Agreement between clinical and laboratory methods assessing tonic and cross‐link components of accommodation and vergence

Neveu¹,

Priot

Philippe³

et al. 2015

Clinical and Experimental Optometry

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Although different optometric tests of accommodation and vergence rely on the same basic principles, the results of this study indicate that clinical and laboratory methods actually involve distinct components. These differences, which are induced by methodological choices, must be taken into account, when comparing studies or when selecting a test to investigate a particular oculomotor component.

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On the Accommodative Convergence and the Proximal Convergence

Ogle¹,

Martens²

1957

Archives of Ophthalmology

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Phoria Testing Distance Effect on Measurement at Various Accommodation Levels

Cited by 21 publications

References 13 publications

The heterophoria of 3–5 year old children as a function of viewing distance and target type

The heterophoria of 3–5 year old children as a function of viewing distance and target type

Agreement between clinical and laboratory methods assessing tonic and cross‐link components of accommodation and vergence

On the Accommodative Convergence and the Proximal Convergence

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