Exotropia: Divergent Strabismus, Types and Causes

You may have noticed in a photo that one eye looks straight ahead while the other seems to drift to the side, or you came across the word "exotropia" in a doctor's report. This is one of the names for strabismus, and ophthalmologists deal with it. I have gathered the key points that help you understand the situation before seeing a doctor.

What exotropia is

Strabismus is a condition in which the eyes point in different directions and do not fixate on the same object at the same time. The objective sign is an asymmetric position of the corneas relative to the corners and margins of the eyelids. Exotropia is divergent strabismus: the eye deviates outward. Sometimes the eye turns inward, upward, or downward, and then other forms are described. Strabismus occurs especially often in young children, but it can appear at any age.

Types of strabismus: divergent, convergent, vertical, alternating

Most often, manifest strabismus is horizontal: convergent (esotropia) and divergent (exotropia). Vertical strabismus is less common — with deviation upward (hypertropia) or downward (hypotropia). Depending on whether one eye or both turn, monocular and alternating strabismus are distinguished. In alternating strabismus, the eyes are used alternately, the amount of deviation is approximately the same, and if amblyopia develops, it is milder. By cause of occurrence, concomitant and paralytic strabismus are distinguished.

When strabismus appears and disappears

Sometimes the deviation is not constant: the eyes are sometimes straight and sometimes diverge. Symptoms may be constant or may come and go. Pseudostrabismus occurs in children with a wide nasal bridge: the shape of the nose changes, and the impression disappears.

Causes of strabismus

The exact cause is not always known. In most children with strabismus it is unknown, and in more than half of cases the problem is present at birth or soon after — congenital strabismus. Often the issue lies in the control of the muscles rather than in their strength. In children, strabismus is often associated with the eye's attempt to overcome a vision problem: myopia, hyperopia, astigmatism. Strabismus can be caused by injuries, paralyses and pareses, CNS diseases, infections (measles), and in adults — diabetes, stroke, brain injury. Strabismus can be a symptom of a rare childhood eye cancer — retinoblastoma.

How strabismus is diagnosed

The doctor examines the eyes and checks how misaligned they are. Tests include examination of the corneal light reflex, the cover-uncover test, fundus examination, a standard ophthalmological examination, and visual acuity testing. A neurological examination is also performed.

When to see an ophthalmologist

You should seek advice if a child has constant strabismus; if the child is older than 3 months and the strabismus comes and goes; if there are any doubts about vision — the child tilts the head to one side or covers one eye. For adults — if strabismus or double vision appears. See an ophthalmologist.

Strabismus itself is not a reason to call an ambulance. Call 103 or 112 if there are signs of a stroke or another life-threatening condition.

• constant strabismus in a child;
• strabismus that comes and goes after 3 months;
• the child covers one eye or tilts the head;
• strabismus or double vision that appears in adulthood.

This material is for reference and does not replace a doctor's consultation.

This content is for reference and does not replace a doctor's consultation. Medical disclaimer