Adult Strabismus and Double Vision: Treatment Options

Adults with an eye turn are often told two things that cannot both be true. The first is that nothing can be done now that they are grown. The second is that anything done would be “just cosmetic.” Neither holds up.

Adult strabismus is common, and its causes are identifiable. The treatment menu — prism, occlusion, vision therapy, botulinum toxin, surgery — has real evidence behind parts of it and thin evidence behind others. Here is our honest map of that territory at Vision & Learning Center.

Key takeaways

• Strabismus affects roughly 2 percent of people worldwide (Hashemi et al., 2019). About 4 percent of adults will develop a new eye turn at some point in life (Martinez-Thompson et al., 2014).
• Nearly half of new adult eye turns come from a nerve palsy. That is why sudden double vision is a neurological symptom first and an eye symptom second (Martinez-Thompson et al., 2014; Glisson, 2019).
• Adults with longstanding strabismus score far lower on validated quality-of-life measures than controls. More than a third said surgery had never been offered to them (Al-Omari et al., 2022).
• Across largely uncontrolled case series, surgical realignment succeeded in about 68 to 85 percent of adults (Mills et al., 2004). The AAO/AAPOS clinical statement frames the operation as restoring or reconstructing normal ocular alignment, with double vision, binocular vision, visual field and head posture among its listed indications (AAO/AAPOS, 2017).
• Adults can regain fusion and even stereopsis after alignment, though the studies showing it are small (Morris et al., 1993; Fatima et al., 2009).

Why adult eyes turn or see double

Strabismus that started in childhood

In a population study in Los Angeles County, a manifest eye turn was present in 2.4 percent of Hispanic/Latino and 2.5 percent of African American preschoolers (MEPEDS, 2008). Some of those children become adults who were never operated on. Others drifted after one operation. Others again look straight, while the eyes never learned to work as a pair. This is the group most often told the door has closed.

A misalignment the brain finally stops compensating for

Many people carry a small latent misalignment for decades, held straight by fusion. They notice trouble only when age, illness, fatigue or long screen days erode the reserve.

In population data from Olmsted County, Minnesota, three such patterns rank second, third and fourth among new adult strabismus, behind nerve palsy (Martinez-Thompson et al., 2014):

• Convergence insufficiency, 15.7 percent
• Small-angle hypertropia, 13.3 percent
• Divergence insufficiency, 10.6 percent

Adult-onset convergence insufficiency has a median age at diagnosis of 68.5 years (Ghadban et al., 2015). It is not only a schoolchild’s diagnosis.

Some clinics label this whole territory “binocular vision dysfunction.” We use the term carefully. The published support for prism treatment of vertical heterophoria is small, retrospective and uncontrolled, and it comes from a single private practice (Doble et al., 2010).

Nerve palsy, thyroid eye disease and brain injury

Paralytic strabismus from a third, fourth or sixth nerve palsy is the largest category of adult-onset strabismus, at 44.2 percent. Incidence rises with age and peaks in the eighth decade (Martinez-Thompson et al., 2014).

Thyroid eye disease restricts the muscles mechanically and is harder to realign surgically. Unplanned reoperation is reported in up to half of those cases (Mills et al., 2004).

Brain injury is the third route. In a specialty brain-injury clinic, 90 percent of patients after traumatic brain injury and 86.7 percent after stroke had an oculomotor dysfunction (Ciuffreda et al., 2007). Strabismus and nerve palsy were more common after stroke. That was a referral sample, so the true rate across all brain injury is lower.

Red flags: when double vision is an emergency

Double vision is a common presentation in both ambulatory and emergency department settings, accounting for about 850,000 such visits a year. Binocular double vision is most often neurologic in origin. Most outpatient diagnoses are not serious, but some causes require rapid diagnosis and treatment (Glisson, 2019). In new binocular double vision, one priority is ruling out serious causes such as an aneurysm, which need urgent intervention (Iliescu et al., 2017).

Get emergency care the same day if double vision arrives suddenly and comes with any of these:

• A drooping eyelid or an enlarged pupil on one side
• Severe headache, especially “the worst headache of my life”
• Eye pain, bulging, or a red, swollen eye
• Weakness, numbness, slurred speech, unsteadiness or a facial droop
• Recent head injury

Double vision that crept in gradually over months is a different conversation. That one belongs in an exam room.

What a visible eye turn actually costs adults

This is the part most often waved away as vanity. The data say otherwise.

In a survey of 40 Swiss headhunters, about three-quarters judged that a person with strabismus would have more difficulty finding a job than someone with straight eyes (Mojon-Azzi & Mojon, 2009). The same recruiters rated strabismic applicants as less attractive and less intelligent, with a larger penalty for women and for outward-turning eyes. That study measured recruiters’ opinions rather than actual hiring decisions. Those opinions are still what applicants are up against.

The validated Adult Strabismus-20 questionnaire puts numbers on the daily cost. Researchers in Irbid, Jordan, compared 79 adults who had had strabismus for at least a year with 40 controls (Al-Omari et al., 2022). Mean total scores were 50.57 versus 88.01. Both subscales were far lower as well: psychosocial 49.59 versus 87.84, and function 51.55 versus 88.19. In that group, 35.4 percent said surgery had never been offered to them.

In adults whose eyes stayed aligned after surgery, quality-of-life scores kept improving between six weeks and one year rather than fading (Hatt et al., 2012).

The other side deserves saying too. A British birth cohort compared 429 adults who had amblyopia with 8432 who did not (Rahi et al., 2006). It found no functionally or clinically significant differences in education, employment, social class, social participation, health or mortality. A lazy eye in childhood does not sentence anyone to a smaller life. A visibly misaligned eye in adulthood is a different exposure, and it is treatable.

The treatment options, one at a time

Prism

Prism does not retrain anything. It bends light so the eyes have less misalignment to overcome.

It is the workhorse for small, comitant deviations. In the population study of adult-onset convergence insufficiency, nearly 88 percent of patients were prescribed prism and fewer than 5 percent had surgery (Ghadban et al., 2015).

The trial evidence is age-specific. In presbyopic adults with convergence insufficiency, base-in prism progressives beat placebo progressives (Teitelbaum et al., 2009). Mean symptom scores dropped from 30.21 to 13.38, against 23.62 on placebo. In children, the same idea failed: base-in prism reading glasses were no better than placebo glasses (Scheiman et al., 2005).

Fresnel press-on prisms let us trial a correction before anything is ground into a lens. That is useful when a nerve palsy is still recovering and the numbers change month to month.

Occlusion and other optical measures

When the deviation is too large or too incomitant for prism, blocking one eye ends the double image. The options run from a lightly frosted lens or Bangerter filter to a patch or an occluding contact lens (Kapoor & Ciuffreda, 2002).

We are not aware of controlled trials establishing its benefit. It is a comfort measure that removes the second image, and we present it that way.

Vision therapy: what it can and cannot address

Office-based vergence and accommodative therapy is the best-supported non-surgical treatment for symptomatic convergence insufficiency. Honest reporting means separating the age groups.

The Cochrane network meta-analysis pooled 12 trials and 1289 participants (Scheiman et al., 2020). It found office-based therapy clearly superior to placebo in children (relative risk 3.04). In adults, the same review concluded that the effectiveness of non-surgical options is less clear.

The adult trial itself shows why. Only office-based therapy changed the clinical signs: near point of convergence moved from 12.8 to 5.3 cm, and positive fusional vergence from 11.3 to 29.7 prism dioptres. Even so, 42 percent reached symptom elimination versus 31 percent on placebo, and more than half were still symptomatic at the end (Scheiman et al., 2005). Adult symptoms are tracked with a validated questionnaire, where a score of 21 or more suggests symptomatic convergence insufficiency (Rouse et al., 2004).

For eye movement disorders after acquired brain injury, Cochrane reviewers found five trials and 116 participants (Rowe et al., 2018). They concluded that the evidence is insufficient to guide treatment decisions. We offer therapy in that setting as a reasonable, low-risk option — not a proven one.

Our clinical position, plainly. Therapy is for three jobs:

• Vergence and accommodative problems
• Building fusion around a small or intermittent deviation
• The work before and after surgery

It is not a way to realign a constant, large-angle eye turn, and we say so at the consultation.

Strabismus surgery

A surgeon repositions or adjusts the tension of one or more eye muscles, usually as a day procedure.

The American Academy of Ophthalmology reviewed 49 reports on the operation in adults (Mills et al., 2004). Successful realignment was achieved in 68 to 85 percent of patients. The reported functional benefits include elimination of double vision, development of binocular fusion, expansion of the binocular visual field and improvement of an abnormal head position. Those reports were largely case series rather than controlled trials, a limitation the review itself names.

The AAO/AAPOS clinical statement describes adult strabismus surgery as an operation that “seeks to restore/reconstruct normal ocular alignment” (AAO/AAPOS, 2017). It adds that “binocular vision can be restored by strabismus surgery,” and that “even some adults who had childhood strabismus can regain fusion following strabismus surgery.”

The same statement lists the indications for surgery:

• Diplopia
• Visual confusion
• Restoration of binocular vision
• Intolerance of prism or occlusion
• Visual field expansion
• Abnormal head posture
• Psychosocial and vocational function

It also warns that affected individuals “may not be offered appropriate surgical treatment because of misconceptions about adult strabismus.” That line is worth having in hand when an insurer calls the operation elective.

The risks belong beside the benefits (Mills et al., 2004):

• New double vision after surgery, in about 1 to 14 percent of patients
• Scleral perforation, in 0.8 to 1.8 percent
• Unplanned reoperation, in up to 21 percent of comitant cases and up to 50 percent in thyroid eye disease

Botulinum toxin

Injecting botulinum toxin into an overacting muscle weakens it temporarily.

The current Cochrane review pooled four randomized trials with 242 participants (Bort-Marti et al., 2023). Those trials covered adults with esotropia or exotropia, plus children with acquired or infantile esotropia. Surgery may be more likely than botulinum toxin to improve or correct the alignment (relative risk 0.72, 95% CI 0.53 to 0.99, low-certainty evidence). In children with acquired or infantile esotropia, botulinum toxin may have little to no effect on achieving binocular single vision compared with surgery. Reported side effects were temporary: partial transient droopy eyelid in 16.7 to 37.0 percent, and transient vertical deviation in 5.6 to 18.5 percent.

Acute sixth nerve palsy is the situation where botulinum toxin is most often proposed. It is worth knowing how thin the trial evidence is there. In the one randomized trial of 47 people, full recovery at four months was not significantly more likely with injection than with observation (risk ratio 1.19, 95% CI 0.96 to 1.48, low-certainty evidence). Complications occurred in 24 percent of injections and 27 percent of participants. The Cochrane reviewers concluded that the included studies provide insufficient evidence to inform treatment decisions (Rowe et al., 2018).

Our own view is that injection remains a reasonable option to discuss in selected cases. That is a clinical judgement, not a trial result.

Can adults regain binocular vision?

Sometimes, and more often than the old teaching allowed.

One series followed 24 adults with congenital or early-onset strabismus who were never aligned in early childhood (Morris et al., 1993). After surgical alignment to within 8 prism dioptres, every patient showed peripheral fusion and half achieved stereopsis.

A later series looked at 15 chronically strabismic adults with no prior fusion (Fatima et al., 2009). By six weeks, none showed suppression, 13 of 15 fused at near, and 13 of 15 had some stereopsis on Titmus testing. Only 5 reached true stereopsis of 100 seconds of arc or better.

Both studies are small and uncontrolled, and neither promises fine depth perception. Impaired stereopsis is the most common deficit in amblyopia under ordinary binocular viewing (Levi et al., 2015). In laboratory studies, people with strabismic amblyopia respond poorly to monocular training, better to dichoptic training and best to direct stereo training.

Amblyopia itself gets harder to treat with age, without becoming impossible. Among 13 to 17-year-olds never previously treated, 47 percent responded to patching with near activities versus 20 percent on glasses alone (Scheiman et al., 2005). Most were left with some residual deficit. Beyond the teens, the controlled acuity data thin out. That is why we set goals around comfort, single vision and function rather than a promised line on the chart.

How we co-manage with strabismus surgeons

We are a developmental optometry practice. We do not perform eye muscle surgery. We work alongside the surgeons who do.

• New or changing double vision is triaged first. Anything carrying the red flags above goes to emergency care or neurology, not onto our schedule.
• Measurement before recommendation. We test cover testing at distance, near and in all gaze positions, near point of convergence, fusional vergence ranges, accommodation, sensory fusion, stereoacuity and refraction. The numbers decide whether prism, therapy, surgery or watchful waiting fits.
• Therapy before surgery where fusion potential needs building, and after surgery where the eyes are newly straight but the brain has not yet learned to use them together.
• Referral with the file, not just a note — serial measurements, prism trials and sensory findings, because surgeons plan from trends.
• Follow-up on our side, because alignment can shift and quality-of-life gains track with staying aligned (Hatt et al., 2012).

Read more

• Understanding binocular vision dysfunction — our complete guide to the condition
• How binocular vision dysfunction affects adults at work and while driving
• Prism lenses for binocular vision dysfunction: an evidence review
• The three grades of binocular vision
• Double vision in children: what it means and what to do
• Our condition pages on double vision and vertical heterophoria

If your eyes turn, drift or double, the useful first step is a full binocular measurement rather than a verdict from a waiting room. That is true whether the trouble started last month or fifty years ago. See what the testing involves on our examinations page, or Schedule an evaluation at our Boynton Beach or Boca Raton office.