Pseudoexotropia 

Updated: May 12, 2021
Author: Barbara L Roque, MD, DPBO, FPAO; Chief Editor: Donny W Suh, MD, MBA, FAAP, FACS 

Overview

Practice Essentials

Pseudoexotropia is a clinically stable condition associated with a positive angle kappa due to macular ectopia. It can be identified early but should be monitored regularly, as a small percentage of cases could develop true strabismus. Parents should be counseled to focus on preventing further macular damage rather than fixing cosmetic appearance. Risk factors include prematurity, high myopia, and chorioretinal infection.

Background

The term pseudoexotropia refers to an apparent outward deviation despite the eyes being well-aligned.[1]   

Pathophysiology

Pseudoexotropia presents with a wide interpupillary distance or a positive angle kappa. Angle kappa is the angle formed between 2 imaginary lines: the visual axis and the pupillary axis. The visual axis is the line connecting the fixation point with the fovea while the pupillary axis is the line that perpendicularly passes through the entrance pupil and the center of curvature of the cornea.  

Because the fovea is displaced temporally in cases with macular dragging (such as in cicatricial retinopathy of prematurity[2] ), positive angle kappa manifests as a nasally displaced corneal light reflex, and translates into a clinical disparity between the prism cover tests and the Hirschberg measurements.  

 

 

Epidemiology

Frequency

United States

The incidence of pseudoexotropia is higher in children with a temporally dragged macula from retinopathy of prematurity.

Sex

No known sexual predilection exists.

Age

The appearance of pseudoexotropia is seen at any age.

Prognosis

The degree of pseudoexotropia is usually stable as long as the associated macular dragging is also stable. In a retrospective review of 65 cases initially diagnosed with pseudostrabismus, 8 patients (12%) developed true strabismus.[3] One of the 8 developed true exotropia while the rest developed true esotropia.4 Risk factors were binocular single vision and the best corrected visual acuity.[3]  In cases with associated pattern strabismus, they can be successfully operated on to address the pattern, without making the pseudoexotropia worse.[4]  

Patient Education

Parents should be counseled to focus on preventing further macular damage rather than fixing cosmetic appearance.

 

Presentation

History

Parents usually report a perception that their child's eyes are turned out. Review of the birth history including gestational age at birth, birthweight, and history of treatment for retinopathy of prematurity are diagnostic clues. A photograph taken during the first few months of life can help in documenting the onset as well as the stability of the pseudoexotropia. 

Physical

Patients appear to have a large angle kappa or nasally deviated corneal light reflex. Cover testing does not show any refixation movement in patients with pseudoexotropia, as opposed to in patients with true exotropia.

Orthoptic exam will show a notable difference between the prism and alternate cover test and the Hirschberg measurements.[5] This suggests that angle kappa can exaggerate or even conceal the true amount of the true heterotropia.  

In the case of macular ectopia, an indirect ophthalmoscope reveals temporal displacement of the macula.

Causes

A common cause of pseudoexotropia is a temporally displaced or dragged macula (macular ectopia) as seen in the cicatricial sequelae of retinopathy of prematurity.[2, 4]  Retinal scarring in the temporal periphery caused by chorioretinal infection with Toxocara canis is another cause of a temporally displaced macula resulting in pseudoexotropia. Macular ectopia can also be seen in cases of high myopia and congenital reitnal folds.

 

 

 

Physical Examination

Certain morphological features of the face can produce a false sense of perception of ouwardly deviated eyes, such as hypertelorism and telecanthus.[3]

 

DDx

Diagnostic Considerations

Clinical diagnosis of pseudoexotropia is reached after ruling out the presence of true manifest or intermittent exotropia.

Differential Diagnoses

 

Workup

Approach Considerations

Pseudoexotropia is a clinical diagnosis. Most of the time, sophisticated workups are not necessary. Appropriate ocular motor evaluation should be performed to rule out any true strabismus. 

Other Tests

A wide-field fundus photography can document the posterior pole pathology such as temporal dragging of the macula.

 

Treatment

Medical Care

No medical treatment is indicated for pseudoexotropia.

Consultations

Patients with suspected pseudoexotropia should be initially examined and followed-up regularly by an ophthalmologist because true exotropia may later develop. For example, a large positive angle kappa may hide an esodeviation, and a negative angle kappa may hide an exodeviation. Associated pattern strabismus may be oprated on without worsening the degree of pseudoexotropia.[4]

 

Follow-up

Further Outpatient Care

A retrospective review of 65 patients initially diagnosed with pseudostrabismus showed that 12% developed true strabismus after a mean follow-up of 25 months.[3] Therefore, a patient with pseudoexotropia should be observed on a regular basis to ensure no subsequent development of true strabismus.[6]

Patient Education

Parents of a child with pseudostrabismus should be reassured that the alignment of their child's eyes is straight (orthotropic). However, follow-up care should be continued because pseudoexotropia can hide a true strabismus.[6, 3]