author={B E Freier and L. D. Pickwell},
  journal={Ophthalmic and Physiological Optics},
Abstract The evidence for the existence, nature and degree of physiological exophoria was examined with respect to a sample of 663 optometric patients. It was found that the mean value for heterophoria is the same for distance and near vision up to the age of the early twenties. After this age, the mean value for distance heterophoria remains unchanged throughout life whilst there is a change in the value for near vision towards exophoria, giving 5 A physiological exophoria. No differences… 

Frequency of Exophoria among the Convergence Insufficiency Patients

This study showed that exophoria is the most common sign among convergence insufficiency patients and orthoptic exercises are the cheapest and easiest solution of this problem.

Near heterophoria in early childhood.

Despite developmental maturation of interpupillary distance, refractive error, and AC/A, in a typical sample of young children the predominant dissociated position is one of exophoria.

Normal heterophoric changes: 20 years' follow-up

An increase in esophoria for distance fixation and a exphoria for near fixation was found in a 20-year follow-up of 100 normal subjects.


  • L. Pickwell
  • Medicine
    Ophthalmic & physiological optics : the journal of the British College of Ophthalmic Opticians
  • 1985
It is concluded that an additional factor other than age must account for the marked increase in the incidence of convergence insufficiency over the age of 60 years.

Normal values of distance heterophoria and fusional vergence ranges and effects of age

Distance base-in and base-out recovery means diminished significantly with age such that recovery values fell outside the norm in subjects in the 61–70 year age group and older, establishing statistical normal values for distance heterophoria and fusional vergence in a non-clinical population.

Distance and near readings of associated heterophoria taken on 500 patients

For near vision a fair degree of association existed between readings of associated phoria and symptoms and it was possible in the under 40 years and 40–59 years age groups to express clinically useful rules regarding the relationship.

Normative Values for the Fusional Amplitudes and the Prevalence of Heterophoria in Adults Khatam-Al-Anbia Eye Hospital - 2009)

The amount of exophoria had not affected the fusional reserves and the presence of hetrophoria was not related to the visual complaints like asthenopia and transient diplopia.

The effect of incipient presbyopia on the correspondence between accommodation and vergence

Data show that the near vision response is limited to the maximum vergence response that can be tolerated and, despite being within the amplitude of accommodation, a stimulus may still appear blurred because the vergence component determines the proportion of available accommodation utilised during near vision.

Orthoptic status before and immediately after heroin detoxification

The eso trend found in these patients may be responsible for the development of acute concomitant esotropia in some patients undergoing heroin detoxification, however, the mechanism for this trend does not appear to be caused by divergence insufficiency or sixth nerve palsy.

Presbyopia among normal individuals

  • A. SpiererB. Shalev
  • Medicine, Psychology
    Graefe's Archive for Clinical and Experimental Ophthalmology
  • 2003
Hyperopia and low amplitude of accommodation at the age of 20 might predispose to early development of presbyopia in normal individuals.




Examinations of the eyes of groups of unselected school children, made in connection with two previous studies, 1 indicated practical orthophoria in distant vision and also at the reading distance.


Fixation disparity measurements indicate that the exophoria which is measured by the von Graefe technique does not exist under binocular conditions, and analysis indicates that presbyopes may have unrestrained use of accommodative convergence.

Practical Orthoptics in the Treatment of Squint

This is a book which can be warmly recommended for it can be confidently stated that no clinician can peruse its pages without benefit and a quickening of his interest in his calling.

The Practice of Orthoptics

  • E. Stark
  • Medicine
    The Indian Medical Gazette
  • 1951
This volume is an amplification of the author's "Manual of Practical Orthoptics," published in 1938. The inclusion of a chapter on the "Orthoptic Treatment of Service Candidates," with special

Effect of multifocal lenses on convergence.

Accommodative-convergence in presbyopia.

  • M. W. MorganH. Peters
  • Medicine
    American journal of optometry and archives of American Academy of Optometry
  • 1951

The variation of phoria with age.

Binocular Anomalies. Professional Press, Chicago

  • 1976

Adaptation to lens and prism induced heterophorias

  • Ph.D. thesis,
  • 1982