V-Pattern Esotropia and Exotropia 

  • Author: Neepa Thacker, MBBS, MS, FRCS, DNB; Chief Editor: Hampton Roy Sr, MD   more...
 
Updated: Dec 5, 2011
 

Background

Duane first described V-pattern strabismus in 1897.[1] Other investigators also studied these phenomena, contributing to the understanding of them. Costenbader and colleagues recommended measuring the horizontal deviations in upgaze and downgaze as part of all routine motility examinations.[2]

Two types of V-patterns can occur, as shown in the images below.

V-pattern exotropia is an exodeviation with greater exotropia in upgaze than in downgaze.

V-pattern exotropia. V-pattern exotropia.

V-pattern esotropia is an esodeviation with greater esotropia in downgaze than in upgaze.

V-pattern esotropia. V-pattern esotropia.

Comitant horizontal deviations are those in which the angle of deviation is the same in all gaze positions. Incomitant horizontal deviations are those in which the angle of deviation varies in different gaze positions. Horizontal deviations may have lateral incomitances and vertical incomitances. In lateral incomitances, significant differences exist in the amount of horizontal deviation in primary gaze versus side gaze, whereas, in vertical incomitances, significant differences exist in the amount of horizontal deviation in upgaze versus downgaze.

When the eyes diverge more than 10 prism diopters (PD) from upgaze to downgaze, an A-pattern is present; when the eyes converge more than 15 PD from upgaze to downgaze, a V-pattern is present.

Other types of vertical incomitances, which are less common, include X, Y, and lambda patterns. This discussion is limited to V-pattern strabismus.

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Pathophysiology

Multiple factors may be responsible for V-pattern strabismus, and, in a given individual, one or more factors may contribute toward its cause.

Inferior oblique muscle overaction

The most widely accepted mechanism contributing to the causation of V-pattern strabismus is associated with inferior oblique muscle overaction and/or relative underaction of the superior oblique muscles, as shown in the images below.

Patient with V-pattern exotropia and inferior obliPatient with V-pattern exotropia and inferior oblique muscle overaction. Patient with V-pattern esotropia and inferior obliPatient with V-pattern esotropia and inferior oblique muscle overaction.

Inferior oblique muscle overaction produces significant horizontal deviation in upgaze. In upgaze, the horizontal action of the inferior oblique muscles is abduction; therefore, inferior oblique muscle overaction produces relative divergence in elevation. A V-pattern results in greater exotropia (or less esotropia) in upgaze and greater esotropia (or less exotropia) in downgaze. Not all V-pattern strabismus is associated with oblique muscle dysfunction.

Facial and orbital configuration

An association exists between individuals with hypoplasia of the malar bones, anti-Mongoloid lid slants, and S-shaped contours of the lower lid, and overaction of the inferior oblique muscles and V-pattern strabismus. Patients with craniosynostosis have shallow orbits, and the angle between the visual axis and the insertion of the inferior oblique muscle is increased. This increased angle increases the abduction ability of the inferior oblique muscles in upgaze, resulting in a V-pattern. Contributing to this condition is the complex interplay of these factors with excyclotorsion of the globe.

Effect of the pulley systems

Upward displacement of the pulley systems around the lateral rectus muscle may cause V-pattern strabismus.

Horizontal muscle overaction

Initially, this theory was believed to be responsible for V-pattern strabismus, but no convincing evidence supports it. In V-pattern esotropia, the medial rectus muscle was believed to overact, thereby increasing esotropia in downgaze, and, in V-pattern exotropia, the lateral rectus muscle overaction was responsible for increased exotropia in upgaze.

Vertical rectus muscle imbalance

One theory states that V-pattern strabismus occurs because of underacting superior recti muscles and corresponding overacting inferior oblique muscles. This hypothesis was applied when nasal and temporal displacements were used to treat A- and V-patterns. This theory has been abandoned.

Abnormal oblique muscle insertions

Alterations of the angle of the insertion of the oblique muscle with the visual axis can reduce cyclorotation and abduction forces and increase the vertical function of the oblique muscle.

Anomalous horizontal rectus muscle insertions

Among the suggested causes of V-pattern strabismus are anomalies of the horizontal rectus scleral insertions. They may be inserted above or below the usual positions.

Acquired form

V-patterns are acquired after superior oblique muscle palsy and are a prominent feature of bilateral superior oblique muscle palsies.

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Epidemiology

Frequency

United States

Although the exact prevalence of V-pattern strabismus in a given population is not known, 12.5-50% of patients with horizontal strabismus have an associated A- or V-pattern. V-pattern esotropia is not as commonly seen as V-pattern exotropia.

Mortality/Morbidity

Patients may experience diplopia that affects their everyday activities, such as driving and reading. In addition, the inability of patients to fuse in different gaze positions can interfere with other activities, including sports and recreation. The cosmetic appearance of V-pattern strabismus coupled with its social implications may be bothersome to patients. Over time, the associated anomalous head position could lead to secondary neck pain and similar problems.

Race

No racial predilection exists.

Sex

No sexual predilection exists.

Age

No age predilection exists.

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Contributor Information and Disclosures
Author

Neepa Thacker, MBBS, MS, FRCS, DNB  Consulting Staff, Department of Pediatric Ophthalmology and Strabismus, Breach Candy Hospital, India

Disclosure: Nothing to disclose.

Coauthor(s)

Arthur L Rosenbaum, MD  Chief, Division of Pediatric Ophthalmology, Professor, Vice Chairman, Department of Ophthalmology, University of California at Los Angeles School of Medicine

Arthur L Rosenbaum, MD is a member of the following medical societies: American Academy of Ophthalmology, American College of Surgeons, and American Medical Association

Disclosure: Nothing to disclose.

Federico G Velez, MD  Assistant Clinical Professor, Department of Ophthalmology, Division of Pediatric Ophthalmology and Strabismus, University of California at Los Angeles School of Medicine

Federico G Velez, MD is a member of the following medical societies: American Academy of Ophthalmology and American Association for Pediatric Ophthalmology and Strabismus

Disclosure: Nothing to disclose.

Specialty Editor Board

Michael J Bartiss, OD, MD  Medical Director, Ophthalmology, Family Eye Care of the Carolinas

Michael J Bartiss, OD, MD is a member of the following medical societies: American Academy of Ophthalmology, American Academy of Pediatrics, American Association for Pediatric Ophthalmology and Strabismus, and North Carolina Medical Society

Disclosure: Nothing to disclose.

Francisco Talavera, PharmD, PhD  Adjunct Assistant Professor, University of Nebraska Medical Center College of Pharmacy; Editor-in-Chief, Medscape Drug Reference

Disclosure: Medscape Salary Employment

J James Rowsey, MD  Former Director of Corneal Services, St Luke's Cataract and Laser Institute

J James Rowsey, MD is a member of the following medical societies: American Academy of Ophthalmology, American Association for the Advancement of Science, American Medical Association, Association for Research in Vision and Ophthalmology, Florida Medical Association, Pan-American Association of Ophthalmology, Sigma Xi, and Southern Medical Association

Disclosure: Nothing to disclose.

Ralph Garzia, OD  Assistant Dean for Clinical and Academic Programs, Associate Professor, College of Optometry, University of Missouri at St Louis

Ralph Garzia, OD is a member of the following medical societies: American Academy of Optometry and American Optometric Association

Disclosure: Nothing to disclose.

Chief Editor

Hampton Roy Sr, MD  Associate Clinical Professor, Department of Ophthalmology, University of Arkansas for Medical Sciences

Hampton Roy Sr, MD is a member of the following medical societies: American Academy of Ophthalmology, American College of Surgeons, and Pan-American Association of Ophthalmology

Disclosure: Nothing to disclose.

References

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V-pattern exotropia.
V-pattern esotropia.
Esotropia and exotropia, V-pattern. In Image 3a, lateral rectus muscle insertion moved toward the open end of V. In Image 3b, medial rectus muscle insertion moved toward the closed end of V.
Esotropia and exotropia, V-pattern. In Image 4a, half tendon width vertical shift of muscle insertion. In Image 4b, full tendon width vertical shift of muscle insertion.
Esotropia and exotropia, V-pattern. In Image 5a, slanting of rectus muscle insertion. In Image 5b, recession and slanting of rectus muscle insertion.
Esotropia and exotropia, V-pattern. Recess-resect procedure in same eye.
Patient with V-pattern exotropia and inferior oblique muscle overaction.
Patient with V-pattern esotropia and inferior oblique muscle overaction.
 
 
 
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