Original Research

Comparison of phoropter and trial frame-based von Graefe heterophoria measures in non-presbyopic participants

Annah L. Tsotetsi, Solani D. Mathebula
African Vision and Eye Health | Vol 80, No 1 | a645 | DOI: https://doi.org/10.4102/aveh.v80i1.645 | © 2021 Solani D. Mathebula | This work is licensed under CC Attribution 4.0
Submitted: 18 December 2020 | Published: 08 November 2021

About the author(s)

Annah L. Tsotetsi, Department of Optometry, Faculty of Health Sciences, Limpopo University, Sovenga, South Africa
Solani D. Mathebula, Department of Optometry, Faculty of Health Sciences, Limpopo University, Sovenga, South Africa


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Abstract

Background: There are several clinical techniques for the subjective measurement of heterophoria. In South Africa, von Graefe (VG) is a commonly used technique to quantify heterophoria using the phoropter.

Purpose: The purpose of the study was to investigate the agreement of VG heterophoria measurement using the phoropter and a trial frame.

Setting: The study was conducted at an Optometry Clinic, University of Limpopo, South Africa.

Methods: Both distance and near horizontal and vertical heterophoria VG measurements were performed on 88 visually-normal university students using the phoropter and trial frame. The handheld rotary prism was used on the trial frame. The 95% limits of agreement in prism diopters were compared using the Bland-Altman statistical test.

Results: For distance horizontal heterophoria, the VG means were 0.39 exophoria ± 2.0Δ and 0.38 exophoria ± 1.8Δ with the phoropter and trial frame respectively. The means for near horizontal heterophoria were 3.69 exophoria ± 3.3Δ and 4.13 exophoria ± 3.27Δ with the phoropter and trial frame. For the vertical heterophoria at distance, the means and standard deviations were 0.18 hyperphoria ± 0.74 and 0.13 hyperphoria ± 0.07Δ, while at near vision they were 0.03 hyperphoria ± 0.71 and 0.07 hyperphoria ± 0.71Δ, respectively.

Conclusion: Measurement of VG heterophoria testing using the phoropter and trial frame showed a high level of agreement for both distance and near vision performed through the phoropter and a trial frame. For clinical and research purposes, the phoropter and trial frame can be used interchangeably for measuring heterophoria.


Keywords

heterophoria; phoropter; trial frame; von Graefe; prism

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