Original Research

A retrospective analysis of heterophoria values in a clinical population aged 18 to 30 years

N. T. Makgaba
African Vision and Eye Health | South African Optometrist: Vol 64, No 4 | a272 | DOI: https://doi.org/10.4102/aveh.v64i4.272 | © 2005 N. T. Makgaba | This work is licensed under CC Attribution 4.0
Submitted: 19 December 2005 | Published: 19 December 2005

About the author(s)

N. T. Makgaba,, South Africa

Full Text:



Information on heterophoria values in South Africans is scanty. The purpose of this paper therefore, is to present information on the distribution of heterophoria in a clinical population aged 18 to 30 years, which hitherto is not available. The data presented here was obtained from the record cards of 475 black South African patients examined at the Optometry clinic, University of Limpopo (Turfloop campus) between 2000 and 2005. The patients were examined by final year students under the supervision of qualified optometrists. Heterophoria was measured for each patient using the von Graefe method. The horizontal heterophoria for distance vision (6 m) ranged from 16 prism diopters (pd) esophoria to 12 pd exophoria with a mean of 0.74 pd exophoria (SD = ± 2.84 pd). For distance vision, esophoria ranged from 0.5 to 16 pd with a mean of 3.08 pd (SD = ± 3.09), while exophoria ranged from 0.5 pd to 12 pd with a mean of 2.21 pd (SD = 1.82 pd). For near vision (0.4 m), the horizontal phorias ranged from 17 pd esophoria to 15 pd exopho-ria with a mean of 3.84 pd exophoria (SD = ± 4.80 pd). The near esophorias ranged from 0.5 to 17 pd with a mean 4.88 pd (SD = ± 3.41), while the exophorias ranged from 1.0 to 15 pd with a mean of 6.30 pd (SD = ± 2.58). Vertical heterophoria for distance vision ranged from 5 to 3 pd right hyperphoria with a mean of 0.05 pd right hyperphoria (SD = ± 0.76) whereas at near it ranged from 4 to 6 pd right hyperphoria


Heterophoria; horizontal phoria; vertical phoria; esophoria; exophoria.


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