What are the treatment options for strabismus?

Strabismus Treatment

Strabismus treatment follows a stepwise approach beginning with optical correction, progressing to observation or prisms for mild cases, then advancing to botulinum toxin injections or surgical intervention for persistent or severe misalignment, with surgery achieving satisfactory alignment in approximately 80% of adults with one procedure. 1, 2

Initial Assessment and Diagnosis

Complete sensorimotor examination is essential, measuring misalignment with prism and alternate cover test at distance and near in all gaze positions. 1 In patients with significant vision loss, use Krimsky, modified Krimsky, or Hirschberg tests instead, as prism and alternate cover testing may be misleading with eccentric fixation. 1

Identify and treat underlying causes of vision loss before strabismus surgery (cataracts, refractive errors, etc.), as this may improve alignment in patients with prior good binocular fusion. 1 For uncorrected aphakia with sensory strabismus, assess fusional potential with a contact lens trial before proceeding to IOL implantation or surgery. 1

Treatment Algorithm

Step 1: Optical Correction

• Correct all significant refractive errors first, as this alone may resolve or improve alignment in some cases. 3
• Verify the optical correction is appropriate for the patient's near activities, particularly in convergence insufficiency. 1

Step 2: Observation

• Monitor without intervention if symptoms are mild, occasional, well-tolerated, or if the patient opposes treatment. 1
• This is appropriate across all strabismus types when symptoms do not significantly impact quality of life. 1

Step 3: Non-Surgical Management

Prism correction (Fresnel or ground-in prisms):

• Effective for small deviations, intermittent deviations, or as temporary treatment before surgery. 1
• Particularly useful for new-onset deviations and divergence insufficiency. 1
• Counsel patients that prism magnitude may need to increase over time and diplopia control without glasses will likely decline. 1

Convergence exercises:

• Office-based training is more effective than home-based exercises in children and young adults for improving positive fusional vergence. 1
• Results are less consistent in adults than children. 1
• Consider for convergence insufficiency with exophoria greater at near, insufficient positive fusional vergence (<20 PD), and distant near point of convergence (>6cm). 1

Step 4: Botulinum Toxin Injection

Chemodenervation can yield long-term improvement in ocular alignment, though periodic injections may be required to maintain results. 1 This is particularly valuable for:

• Patients with residual or progressive deviations after maximal surgical correction. 4
• Trial realignment before IOL implantation in patients at risk for symptomatic diplopia. 1
• Augmentation of strabismus surgery in patients with very large angles who hesitate to have surgery on both eyes. 1

Step 5: Surgical Intervention

Surgery is indicated when:

• Conservative measures fail to control symptoms
• Deviation is large or causes significant diplopia, loss of binocular vision, compensatory head posture, or inability to make eye contact 1
• Patient desires definitive correction

Surgical considerations:

Adjustable sutures are frequently used in adults, offering advantages including a second chance at obtaining satisfactory alignment and minimizing postoperative diplopia risk. 1 This technique is most helpful in reoperations and unpredictable cases (restrictive or paralytic strabismus). 1

Surgical dosing typically requires greater magnitude than standard childhood tables, particularly for medial rectus recessions in divergence insufficiency. 1 Check convergence amplitudes at near preoperatively—robust amplitudes generally protect against postoperative diplopia with convergence insufficiency. 1

For specific conditions:

• Divergence insufficiency/sagging eye syndrome: Bilateral lateral rectus resection, bilateral medial rectus recession, or unilateral medial rectus recession with lateral rectus resection. 1 More than typical medial rectus recession is usually needed. 1
• Sensory strabismus: Current surgical techniques with many surgeons favoring adjustable sutures. 1 Large recessions can improve concomitant ptosis/enophthalmos; large resections can reduce proptosis/exophthalmos. 1
• Small deviations (<8 PD horizontal, <3 PD vertical): Tenotomy procedure (partial, central snip) may successfully obviate prism correction. 1

Special Populations and Situations

Trauma-related strabismus: Defer surgery for at least 6 months post-injury to allow spontaneous improvement and stabilization, as diplopia may be transient but is unlikely to resolve spontaneously if persistent beyond 6 months. 1, 5 Surgery was required in only 7-24% of orbital floor fracture cases. 1, 5

Progressive conditions (e.g., CPEO): Maximal bilateral surgery (8mm or 17mm lateral rectus recessions with 7mm medial rectus resections using adjustable sutures) significantly improves alignment, but strabismus often recurs due to disease progression. 4 Botulinum toxin is invaluable for maintaining alignment after maximal surgery. 4

Anticoagulation: Many surgeons do not routinely stop anticoagulants for strabismus surgery, though temporary discontinuation may reduce intraoperative bleeding. 1 Consultation with the prescribing physician is advised, and anticoagulation should be restarted immediately or shortly after the procedure. 1

Surgical Risks and Complications

Common complications include:

• Residual misalignment requiring reoperation (most common) 1
• Scleral perforation (rare, usually without sequelae but increases risk of retinal detachment, vitreous hemorrhage, endophthalmitis) 1
• Altered eyelid position (common with inferior/superior rectus surgery) 1
• Oculocardiac reflex (67.9%) or asystole (0.11%), both usually brief and inconsequential 1

Rare but serious complications include:

• Endophthalmitis (1 in 30,000–1 in 185,000) 1
• Anterior segment ischemia (1 in 6,000; higher risk with age, vascular factors, operating on ≥3 muscles) 1
• Lost muscle (1 in 4,500; more likely in adults) 1
• Diplopia, rarely intractable (0.8%; more likely in adults) 1

Expected Outcomes

Approximately 80% of adult patients achieve satisfactory alignment with one surgical procedure. 2 The majority of adults experience improvement in binocular function even with longstanding strabismus, most commonly expansion of binocular visual fields, with some regaining stereopsis. 2 Consequently, adult strabismus surgery is not merely cosmetic in most cases. 2

Critical Pitfalls to Avoid

• Do not assume adult strabismus cannot be treated—this is a common misconception among patients and providers. 2
• Do not perform strabismus surgery before addressing treatable vision loss, as this may improve alignment or increase diplopia symptoms. 1
• Do not rush to surgery after orbital trauma—wait 6 months for stabilization. 1, 5
• Do not use standard pediatric surgical dosing in adults—larger corrections are typically needed, especially for divergence insufficiency. 1
• Do not operate on three or more muscles simultaneously without careful consideration of anterior segment ischemia risk, particularly in older patients with vascular risk factors. 1