What is the recommended treatment approach for an adult patient with strabismus, including the role of surgery and post-operative care?

Strabismus Surgery in Adults

Strabismus surgery in adults is highly effective and safe, with approximately 80-85% of patients achieving satisfactory alignment after one procedure, and the risk of sight-threatening complications is remarkably low at approximately 1 in 2,400. 1, 2, 3

Treatment Algorithm

Step 1: Initial Assessment and Refractive Correction

• Perform complete sensorimotor examination measuring misalignment with prism and alternate cover test at distance and near in all gaze positions 4
• Correct all significant refractive errors first, as this alone may resolve or improve alignment in some cases, particularly in patients with hyperopia or anisometropia 1, 4
• Verify optical correction is appropriate for near activities, especially in convergence insufficiency 4
• Obtain manifest and cycloplegic refraction to identify refractive barriers to binocular alignment 1

Step 2: Conservative Management (When Appropriate)

• Monitor without intervention if symptoms are mild, occasional, well-tolerated, or if the patient opposes treatment 4
• Prescribe prism correction for small deviations (≤8 prism diopters horizontally, <3 prism diopters vertically), intermittent deviations, or as temporary treatment before surgery 1, 4
• Consider convergence exercises in younger adults, though these are less effective in older adults 4
• Prism testing should simulate desired postsurgical alignment, though responses can be misleading in childhood-onset strabismus due to anomalous retinal correspondence 1

Step 3: Surgical Intervention

Surgery is indicated when:

• Conservative measures fail to control symptoms 4
• Deviation is large or causes significant diplopia 4
• Patient desires definitive correction for psychosocial or functional reasons 4

Surgical approach:

• Use adjustable sutures in most adult cases, particularly for reoperations and unpredictable cases such as restrictive or paralytic strabismus 1, 4
• Adjustable sutures offer a second chance at obtaining satisfactory alignment and minimize postoperative diplopia risk 1
• Timing of adjustment varies from immediately in the operating room to several days postoperatively 1
• Surgical dosing typically requires greater magnitude than standard childhood tables, particularly for medial rectus recessions 4
• For small deviations, consider tenotomy procedures (partial, central snip) or single rectus muscle surgery 1

Special Considerations

Childhood-Onset Strabismus Presenting in Adulthood

• Over 90% of adults with longstanding childhood strabismus demonstrate improvement in alignment or binocular function after surgery 1
• 86% achieve postoperative binocularity when motor alignment is within 8 prism diopters of orthophoria 1
• Prism testing is often misleading due to anomalous retinal correspondence, but patients rapidly readapt postoperatively with very low incidence of persistent diplopia 1
• Review prior surgical records and inspect conjunctival scars and interpalpebral fissures for evidence of previous muscle surgery 1

Trauma-Related Strabismus

• Defer surgery for at least 6 months post-injury to allow spontaneous improvement and stabilization 1, 4
• Surgery was required in only 7-24% of orbital floor fracture cases 1, 4
• Diplopia that persists beyond 6 months is unlikely to resolve spontaneously 1

Anticoagulation Management

• Most strabismus surgeons do not routinely stop anticoagulants for strabismus surgery 1
• Consult with prescribing physician if considering temporary discontinuation 1
• Restart anticoagulation immediately or shortly after the procedure 1
• Absorbable gelatin sponges with or without thrombin may be useful for difficult cases 1

Postoperative Care and Complications

Common Minor Complications (Self-Limited or Treated with Topical Medications)

• Foreign body sensation, corneal abrasion, subconjunctival hemorrhage, chemosis 1
• Delle formation (2.2%-18.9%, higher risk in reoperations) 1
• Pyogenic granuloma (2.1%) 1
• Epithelial inclusion cyst (0.25%) 1

Moderate Complications Requiring Attention

• Overcorrection or undercorrection may require additional strabismus surgery 1
• Altered eyelid position, particularly with inferior or superior rectus surgery and in thyroid ophthalmopathy patients 1
• Globe perforation (0.08%-5.1%), though most cases have no sequelae 1
• Oculocardiac reflex (67.9%) or asystole (0.11%), both usually brief and of no consequence 1

Rare but Serious Complications

• Endophthalmitis (1 in 30,000 to 1 in 185,000) 1
• Surgically induced necrotizing scleritis (1 in 4,000; more likely in adults) 1
• Slipped muscle (1 in 1,500) 1
• Lost muscle (1 in 4,500; more likely in adults) 1
• Anterior segment ischemia (1 in 6,000; higher risk with age, vascular risk factors, and operating on three or more muscles) 1
• Intractable diplopia (0.8%; more likely in adults) 1
• Retinal detachment (1 in 10,000 to 1 in 40,000) 1

Severe complications overall occur in approximately 1 in 400 cases, with poor outcomes in 1 in 2,400. 1

Critical Pitfalls to Avoid

• Do not assume adult strabismus cannot be treated - most patients can be successfully managed 4, 2
• Do not perform strabismus surgery before addressing treatable vision loss such as cataracts or significant refractive errors 4
• Do not rush to surgery after orbital trauma - wait minimum 6 months for stabilization 1, 4
• Do not use standard pediatric surgical dosing in adults - greater magnitude is typically required 4
• Do not operate on three or more muscles simultaneously without careful consideration due to increased risk of anterior segment ischemia 1, 4

Provider Requirements

Diagnosis and management of adult strabismus and its complications require the training, clinical judgment, and experience of a pediatric ophthalmologist or strabismologist. 1 Consultation with subspecialists in retina, infectious disease, rheumatology, or neuro-ophthalmology may be indicated for specific complications 1

Outcomes and Patient Counseling

• Motor success (satisfactory alignment) is achieved in 80-85% of patients after one procedure 2, 3
• Sensory success (binocular function improvement) occurs in 81% of patients with adult-onset strabismus and 25% of those with childhood-onset strabismus 3
• Subjective success is 94% in both groups 3
• Transient postoperative diplopia is common, but persistent diplopia after successful surgery occurs in only 1% or fewer patients 1
• Many patients experience expansion of binocular visual fields and some regain stereopsis even with longstanding strabismus 2