What is the treatment for diplopia (double vision) following herpes zoster (shingles)?

Treatment of Diplopia Following Herpes Zoster (Shingles)

For diplopia following herpes zoster ophthalmicus, initiate oral antiviral therapy immediately (valacyclovir 1 gram three times daily for 7 days or famciclovir 500 mg three times daily for 7 days), then observe for 4-6 months as most cranial nerve palsies resolve spontaneously, reserving prism glasses or strabismus surgery only for persistent diplopia after this waiting period. 1, 2, 3

Immediate Antiviral Treatment

• Start antiviral therapy within 48-72 hours of herpes zoster onset to decrease pain and reduce complications, including neurological manifestations like diplopia 3
• Valacyclovir 1 gram three times daily for 7 days is the standard oral regimen for herpes zoster 1
• Famciclovir 500 mg three times daily for 7 days is an equally effective alternative 2
• Diplopia from cranial nerve palsy occurs in less than 30% of herpes zoster ophthalmicus cases 3

Diagnostic Workup

• Obtain neuroimaging (MRI or CT) in all patients with diplopia following herpes zoster to rule out complications and other causes 3
• Consider polymerase chain reaction and serology on paired serum and cerebrospinal fluid samples if neurological signs are present or imaging is abnormal 3
• Perform full orthoptic examination including prism alternate cover testing to quantify the ocular misalignment 4, 5

Conservative Management Strategy

• Observe for 4-6 months after onset, as cranial nerve palsies from herpes zoster typically resolve spontaneously 4, 3, 5
• The prognosis for visual recovery is excellent for patients with isolated ocular motor cranial nerve palsy from varicella zoster virus 3
• Microvascular causes of diplopia (which can occur with herpes zoster) often spontaneously resolve within six months 5

Temporary Symptomatic Relief Options

• Occlusion of one eye (using a patch or tape) eliminates diplopia immediately but sacrifices depth perception 4
• Fresnel prisms applied to glasses can provide temporary relief while awaiting spontaneous resolution 4
• Prism glasses (ground-in prisms) offer more permanent optical correction if the deviation is stable and small 4, 6
• Botulinum toxin injection into extraocular muscles is another conservative option for temporary management 4

Surgical Intervention Criteria

• Wait a minimum of 4-6 months before considering strabismus surgery to ensure the misalignment has stabilized 4
• Surgery aims to eliminate diplopia in primary position and downgaze, and to enlarge the field of binocular single vision 4
• Adjustable sutures are often helpful in these cases given the complexity of post-inflammatory strabismus 4
• Multiple surgeries and long-term prism use may be required, as complete elimination of diplopia is difficult when misalignment is incomitant 4

Critical Pitfalls to Avoid

• Do not delay antiviral treatment beyond 72 hours, as efficacy decreases significantly after this window 3
• Do not rush to surgery before 4-6 months, as most cases improve spontaneously and premature intervention may result in overcorrection 4, 5
• Do not assume all diplopia is from muscle palsy alone—obtain imaging to exclude other complications like orbital inflammation, cavernous sinus involvement, or vasculitis 3
• Distinguish binocular from monocular diplopia by having the patient cover each eye separately; monocular diplopia has different causes (refractive error, cataract, retinal disease) requiring ophthalmologic management 6

Special Considerations for Severe Cases

• Intravenous acyclovir is reserved for patients with neurological complications beyond isolated cranial nerve palsy, such as encephalitis or retinal involvement 3
• Patients with isolated optic neuropathy or cranial nerve palsy can be managed with oral antivirals alone 3
• Consider short burst of oral corticosteroids (after confirming antiviral coverage) to hasten recovery and reduce inflammation, though this is more established for orbital trauma than herpes zoster 4