---

Preservatives in Eye Drops

Definition and Purpose

• Effectively inhibit a broad spectrum of microorganisms
• Be non-toxic to ocular surface tissues
• Be stable and soluble at required concentrations
• Not interfere with the active drug

---

Commonly Used Preservatives

---

Mechanism of Toxicity of BAK

1. Disruption of the tear film lipid layer - reduces tear film stability, causes faster evaporation
2. Damage to corneal epithelial cells - increases cell permeability, alters tight junctions, triggers apoptosis
3. Goblet cell loss - reduces mucin secretion, worsening dry eye
4. Neurogenic inflammation - damages corneal nerve endings, causes neuropathy
5. Trabecular meshwork toxicity - relevant in long-term glaucoma patients
6. Pro-inflammatory activation - upregulates inflammatory cytokines (IL-1, TNF-α), activates macrophages and mast cells
7. Sub-conjunctival fibrosis - compromises bleb function after filtration surgery

---

Side Effects / Adverse Effects

Ocular Surface

• Punctate epithelial keratopathy (PEK) - most common finding; stains with rose bengal or fluorescein
• Toxic ulcerative keratopathy - in severe cases
• Dry eye syndrome / Keratoconjunctivitis sicca (KCS) worsening
• Conjunctival hyperemia and chemosis
• Follicular conjunctivitis (especially with thimerosal)
• Squamous metaplasia of conjunctival epithelium
• Goblet cell loss - reduced conjunctival mucin
• Cicatricial changes - subconjunctival fibrosis with chronic exposure
• Corneal sub-basal nerve fiber loss (detected on confocal microscopy)

Allergic/Immune-Mediated

• Contact allergy / allergic blepharoconjunctivitis - especially thimerosal
• Giant papillary conjunctivitis with chronic use

Clinical Consequences

• Compromised filtration surgery outcomes - BAK-induced conjunctival fibrosis reduces bleb success in trabeculectomy
• Poor compliance - symptoms cause patients to discontinue glaucoma drops
• Iatrogenic OSD in glaucoma patients - most clinically significant group (using multiple preserved drops chronically)

Systemic Effects

• All ophthalmic medications can be systemically absorbed via nasolacrimal drainage
• BAK: mild systemic toxicity at ophthalmic doses
• Chlorobutanol: CNS depression in large amounts (rarely relevant)
• Thimerosal: mercury toxicity with prolonged use (main reason it was discontinued)

---

Risk Factors for Preservative Toxicity

• High frequency of instillation (>3-4 times/day)
• Multiple preserved preparations used simultaneously (additive BAK exposure)
• Pre-existing ocular surface disease (dry eye, blepharitis)
• Punctal occlusion (reduces drainage, increases contact time)
• Contact lens wear
• Long-term use (months to years, as in glaucoma)

---

Treatment / Management

Principle: Reduce or eliminate preservative exposure

• First-line approach; use unit-dose (single-use) vials wherever possible
• PF artificial tears for dry eye
• PF versions of glaucoma drops (e.g., PF timolol, PF latanoprost, PF dorzolamide) are available
• Multi-dose PF systems (e.g., ABAK filter technology) - eliminate preservative at the nozzle

• Substitute BAK-containing drops with Polyquad-, Purite-, or SofZia-containing equivalents when PF unavailable
• Polyquad and Purite exhibit significantly lower ocular surface toxicity than BAK
• Caveat: benefits vs BAK largely still being established (2024 review - PMID 39098762)

• Fixed-dose combination drops (e.g., dorzolamide/timolol) - one bottle = less total BAK exposure
• Laser procedures (SLT - selective laser trabeculoplasty) to reduce need for topical drops
• Incisional surgery (trabeculectomy, MIGS) to allow drop reduction

• Preservative-free artificial tears / lubricants (hyaluronic acid, CMC)
• Topical cyclosporin A 0.05% (Restasis) - for inflammatory OSD
• Lifitegrast drops - LFA-1 antagonist for dry eye
• Punctal plugs (once preservative burden reduced) - increase tear retention
• Warm compresses and lid hygiene - for meibomian gland dysfunction component
• Bandage contact lenses - for severe corneal epithelial breakdown
• Autologous serum drops - for severe, refractory OSD

---

Key Exam Points (High-Yield)

1. BAK is the most common and most studied toxic preservative in ophthalmic formulations
2. Mechanism: detergent disruption of lipid bilayer + inflammatory activation
3. Most common sign: punctate epithelial keratopathy (PEK)
4. Most at-risk group: glaucoma patients on multiple chronic drops
5. Newer preservatives (Polyquad, Purite, SofZia) are better tolerated but not entirely innocuous
6. Treatment cornerstone: switch to preservative-free formulations; use fixed combinations; consider laser/surgical alternatives
7. Thimerosal is largely obsolete due to allergy and mercury toxicity
8. Post-trabeculectomy: chronic BAK exposure causes conjunctival fibrosis that reduces surgical success
9. Preservative-free rule of thumb: use PF when drops needed >3-4 times/day, in dry eye, or after ocular surface surgery

---

• Kanski's Clinical Ophthalmology: A Systematic Approach, 10th Ed. - Tear substitutes section
• Goodman & Gilman's Pharmacological Basis of Therapeutics - Ophthalmic toxicity
• Katzung's Basic and Clinical Pharmacology, 16th Ed. - Preservatives
• Kahook et al. "Preservatives and ocular surface disease: A review." Ocular Surface, 2024 (PMID 39098762) - a recent comprehensive review confirming current clinical recommendations

---

Intraoperative Floppy Iris Syndrome (IFIS)

Definition

---

Classic Triad (Must Know)

Not all three features need to be present - many patients show only one or two components.

---

Etiology and Pathophysiology

Primary Cause - Alpha-1 Adrenergic Antagonists

1. Pharmacological blockade of dilator muscle - prevents effective mydriasis
2. Structural changes / atrophy of iris dilator smooth muscle with chronic use
3. Loss of iris tone and rigidity - the iris becomes flaccid ("floppy")

Drug-Specific Risk (Incidence of IFIS)

Why Stopping the Drug Does NOT Help

• IFIS has been reported years after drug discontinuation (Nguyen et al., 2007)
• Chronic pharmacological inhibition leads to permanent structural atrophy of iris dilator muscle
• Stopping tamsulosin before surgery does NOT significantly reduce IFIS risk
• Therefore: always ask about past use of alpha-blockers, not just current use

Other Reported Causes (Less Common)

• Other medications: finasteride, minocycline, antipsychotics (with α-blocking properties)
• Pseudoexfoliation syndrome (associated with poor pupillary dilation)
• Small pupil from any cause

---

Clinical Significance / Why It Matters

• Posterior capsule rupture - most feared; can lead to vitreous loss and poor visual outcomes
• Iris trauma / iris damage - from phaco tip or instruments
• Vitreous loss - secondary to capsule rupture
• Dropped nucleus - lens material into vitreous
• Endophthalmitis risk increases with vitreous loss
• Worse visual outcomes overall

---

Preoperative Assessment

History (Critical)

• Always ask about alpha-blocker use (current AND past) in any male patient undergoing cataract surgery
• Age group: elderly men with BPH are the typical demographic
• Drug history must specifically prompt for tamsulosin, silodosin, alfuzosin, doxazosin, terazosin, prazosin

Kanski's Tip:

"Systemic alpha-blockers (e.g. tamsulosin) are the main cause of intraocular floppy iris syndrome when undertaking phacoemulsification."

• Kanski's Clinical Ophthalmology, 10th Ed.

Preoperative Workup Additions

• Biometry as usual
• Examine pupil size and dilation response preoperatively
• Inform the surgical team so appropriate adjuncts are prepared

---

Management

Principle: Anticipate, Prepare, and Adapt

A. Preoperative Strategies

1. Do NOT stop alpha-blocker (stopping does not reduce risk and may worsen BPH)
2. Warn the patient about increased surgical risk and possible complications
3. Maximize preoperative mydriasis:
   • Tropicamide 1% + phenylephrine 2.5-10% (standard mydriatics)
   • Consider adding NSAIDs (e.g., ketorolac, diclofenac drops) preoperatively - reduce intraoperative miosis by blocking prostaglandin release
   • Atropine 1% preoperatively (longer-acting mydriatic)
4. Consider early referral to experienced vitreoretinal surgeon if posterior capsule rupture risk is deemed high

B. Intraoperative Strategies

Pharmacological

• Intracameral phenylephrine (e.g., 1:10,000 or 1:100,000 dilution) - injected into anterior chamber to directly dilate iris; bypasses systemic alpha-blockade
• "Shugarcaine" (intracameral cocktail): preservative-free lidocaine 1% + bisulfite-free epinephrine in BSS - provides analgesia + pupil dilation + iris stabilization; commonly used in IFIS
• Intracameral atropine - used in some centers
• Viscoelastics (OVDs - ophthalmic viscosurgical devices):
  • Dispersive OVD (e.g., Viscoat - sodium hyaluronate + chondroitin sulfate): used to coat and "cushion" the iris, prevent prolapse
  • Technique: "soft-shell" technique - dispersive OVD placed under a cohesive OVD to push iris back

Mechanical / Surgical Adjuncts

Surgical Technique Modifications

• Use smaller phaco tip to reduce fluid turbulence
• Reduce irrigation flow rates and aspiration - lower vacuum settings to minimize iris flutter
• Use cohesive OVD to maintain anterior chamber depth
• Avoid wound distortion - well-constructed incisions prevent iris prolapse
• Consider smaller capsulorhexis initially
• Bimanual microincision phacoemulsification (MICS) - smaller incisions reduce iris prolapse tendency
• Have a vitreoretinal surgeon on standby or alert for complex cases

---

Key Exam Points - High Yield Summary

---

• Kanski's Clinical Ophthalmology: A Systematic Approach, 10th Ed. - Systemic preoperative assessment
• Campbell-Walsh-Wein Urology, 3-Volume Set - Alpha-blocker complications
• Barash's Clinical Anesthesia, 9th Ed. - Ophthalmic anesthesia; IFIS management
• Lippincott Illustrated Reviews: Pharmacology - Alpha-blocker adverse effects

---

Botulinum Toxin (Botox) in Ophthalmology

Background

---

Mechanism of Action

1. BoNT is produced by Clostridium botulinum (gram-positive, anaerobic)
2. Injected toxin binds to presynaptic cholinergic neurons
3. Enters the cell by endocytosis
4. Cleaves SNARE proteins (specifically SNAP-25 for type A) - prevents docking and fusion of acetylcholine-containing vesicles
5. Results in flaccid paralysis of injected muscle (skeletal) and reduced activity at cholinergic autonomic synapses
6. Effect onset: 3-7 days; maximal effect: 1-2 weeks; duration: 3-4 months
7. Recovery: requires nerve sprouting (not receptor regeneration) - hence reversible but slow

---

Ophthalmic Indications

1. Strabismus (Chemodenervation)

• Takes several days to develop
• Maximal at 1-2 weeks post-injection
• Usually worn off by 3 months
• ~16% adults and 25% children develop temporary ptosis as side effect

---

2. Benign Essential Blepharospasm (BEB)

• Meige syndrome = blepharospasm + oromandibular dystonia
• Brueghel syndrome = similar combination

• Botulinum toxin injection: 2.5-5 units injected subcutaneously at 3-4 periocular sites (orbicularis oculi)
• Affords relief in ~95% of patients
• Repeat injections required every 3 months
• Surgery (myectomy) reserved for non-responders/intolerant patients

---

3. Hemifacial Spasm

---

4. Spastic / Involutional Entropion

• BoNT injected into the lower lid pre-tarsal orbicularis muscle
• Temporarily paralyzes the overriding orbicularis
• Useful as temporary measure or in patients unfit for surgery
• Effect lasts 3-4 months; may need repeat

---

5. Endocrine (Thyroid) Orbitopathy (Graves' Ophthalmopathy)

• Upper eyelid retraction - injection into Müller's muscle (superior tarsal muscle) or levator aponeurosis via conjunctival approach; reduces lid retraction
• Restricted extraocular muscles - injection into fibrotic/overacting muscle (e.g., inferior rectus causing hypotropia) as alternative or bridge to surgery
• Useful in active phase when surgery is contraindicated

---

6. Facial Palsy (CN VII Palsy)

• Protective ptosis: BoNT into levator palpebrae superioris → intentional ptosis to protect cornea from exposure keratopathy (lagophthalmos)
• Used while awaiting recovery of facial nerve function
• Alternative to tarsorrhaphy (reversible)

---

7. Convergence Spasm (Spasm of Near Reflex)

• Rare; presents with intermittent esotropia, miosis, and accommodative spasm
• BoNT to medial recti can provide relief

---

8. Cosmetic Uses (Oculoplastic)

• Glabellar lines (frown lines between brows) - procerus and corrugator supercilii muscles
• Crow's feet (lateral orbital rhytids) - lateral orbicularis oculi
• Brow lift - injection of frontalis inferior fibers to achieve brow elevation
• Hyperfunctional forehead lines

---

9. Other / Emerging Uses

• Gustatory hyperlacrimation (Crocodile tears) - after aberrant regeneration of CN VII; BoNT into lacrimal gland
• Chronic migraine with ocular features - periorbital injection sites
• Nystagmus - retrobulbar injection (experimental, rarely used)
• Dacryocystorhinostomy (DCR) adjunct - prevent pump failure
• Brow ptosis - corrugator/procerus injection for brow lift

---

Contraindications

---

Side Effects / Complications

Local (at injection site)

• Ptosis (most common - from spread to levator) - especially in strabismus and brow/glabellar injections
• Lagophthalmos (inadequate lid closure) - from orbicularis paralysis
• Diplopia - from spread to adjacent extraocular muscles
• Dry eye - from orbicularis paralysis reducing blink/pumping
• Ecchymosis / bruising at injection site
• Epiphora (watering eye) - reduced blink
• Ectropion - lower lid

Systemic (rare - due to distant spread)

• Generalized weakness
• Dysphagia, dysphonia
• Respiratory paralysis (rare but potentially fatal) - FDA black box warning
• Flu-like symptoms

---

Dosing Reference (Approximate)

---

High-Yield Exam Summary

---

• Kanski's Clinical Ophthalmology, 10th Ed. - Botulinum Toxin (strabismus), Blepharospasm section
• Goodman & Gilman's Pharmacological Basis of Therapeutics - Botulinum Toxin mechanism and ophthalmic use
• Leszczynska et al. "Five decades of the use of botulinum toxin in ophthalmology." Indian J Ophthalmol, 2024 (PMID 38317306) - comprehensive recent review

---

Phakonit / Phaconit

Full Form and Definition

---

Historical Background

• The concept was first described in Agarwal's textbook: Phacoemulsification, Laser Cataract Surgery and Foldable IOLs (1st ed., 1998)
• Also called "No Anesthesia Cataract Surgery" when combined with topical/no anesthesia technique

---

Concept: Coaxial vs. Bimanual Phaco

---

Instruments Used

1. Sleeveless phaco needle (0.9 mm) - delivers ultrasound energy and aspiration
2. Irrigation chopper (0.9 mm) - simultaneously delivers irrigation fluid and acts as a second instrument for nuclear manipulation
3. Phakonit knife (0.9 mm) - to create both incisions
4. For Microphakonit: 0.7 mm phaco needle tip + 0.7 mm irrigation chopper + 0.8 mm microphakonit knife
5. Gas-forced infusion (air pump) - used in Microphakonit to control surge and maintain anterior chamber stability (since conventional gravity-fed irrigation cannot maintain adequate pressure through such small ports)

---

Surgical Technique (Step by Step)

1. Anesthesia: Topical (or no anesthesia technique)
2. Two incisions of 0.9 mm each, placed approximately 180° apart (main + sideport - both equal size)
3. OVD injection through sideport to maintain anterior chamber
4. Continuous curvilinear capsulorhexis (CCC): 5-6 mm, using 26-gauge bent cystotome or 25-gauge CCC forceps
5. Hydrodissection: Cortical cleaving; can be done from both incisions (advantage: subincisional cortex is also hydrodissected). Caution - decompress AC by posterior pressure on scleral lip to avoid posterior capsular rent from fluid build-up
6. Phacoemulsification: Sleeveless phaco tip in one hand, irrigation chopper in the other - nucleus emulsified using stop-and-chop or phaco chop technique
7. Irrigation/Aspiration (I/A): Bimanual I/A - aspiration and irrigation through separate 0.9 mm instruments
8. IOL implantation: Main incision must be enlarged (to ~2.4-3.2 mm depending on IOL) for IOL insertion - since no IOL currently passes through a sub-1 mm incision
9. Wound is self-sealing; usually no sutures needed

---

Classification of MICS

---

Advantages of Phakonit

1. Smaller Incision Benefits

• Reduced surgically induced astigmatism (SIA) - smaller incision = less corneal distortion
• Faster wound healing and less postoperative wound leakage
• Self-sealing incisions - no sutures needed
• Reduced risk of wound-related complications (wound dehiscence, iris prolapse through incision)

2. Better Fluidics

• Bimanual separation of irrigation and aspiration allows better anterior chamber control
• Irrigation from a separate port = more balanced fluid dynamics
• Ability to hydrodissect from both sides (catches subincisional cortex better)
• Reduced corneal thermal injury - no heat buildup from sleeve (sleeveless tip loses heat faster)

3. Improved Access and Maneuverability

• Irrigation chopper can be used as second manipulating instrument for nuclear chopping
• Better access to subincisional cortex during I/A
• Can operate through a clear corneal incision without requiring enlargement for phaco (only enlarged for IOL)

4. Other

• Reduced risk of endophthalmitis (smaller entry wound = less risk of ingress)
• Less postoperative inflammation
• Faster visual rehabilitation
• Can be combined with femtosecond laser for capsulotomy and lens fragmentation

---

Disadvantages / Limitations

1. IOL implantation still requires incision enlargement - no IOL currently fits through a sub-1 mm incision; main incision must be widened to ~2.4 mm or more, negating some of the wound advantage
2. Steep learning curve - bimanual technique requires relearning of hand movements
3. Chamber instability / surge - without the irrigating sleeve around the phaco tip, the anterior chamber can be less stable; solved by gas-forced infusion in Microphakonit
4. Risk of wound burns - sleeveless tip can cause wound burn if not using appropriate fluidics
5. Limited availability of instruments - very specialized 0.7-0.9 mm instrumentation required
6. Hydrodissection risk - minimal fluid egress around instruments; too much fluid can cause posterior capsular rent; requires careful decompression of AC
7. Not ideal for very dense nuclei (grade IV-V) where higher ultrasound energy is needed

---

Phakonit vs. Microphakonit - Key Differences

---

IOL Considerations in Phakonit

• Standard rollable/foldable IOLs still require incision enlargement to ~2.4-3.2 mm
• Research ongoing into ultra-thin rollable IOLs (<1 mm delivery system) for true sub-1 mm implantation
• Acritec IOL was one of the first IOLs reported for use with Phakonit (Agarwal 2003) - could be implanted through a slightly enlarged but still small incision
• Future: flexible IOLs with nanomaterial technology may allow true sub-1 mm IOL implantation

---

Key Exam Points - High Yield Summary

---

• Agarwal A et al. "Phakonit: phacoemulsification through a 0.9 mm incision." J Cataract Refract Surg 2001;27:1548-1552
• Agarwal A et al. "Microphakonit: 700 micron cataract surgery." Clin Ophthalmol 2007; PMC2701137
• Kanski's Clinical Ophthalmology, 10th Ed. - Phacoemulsification technique
• Agarwal A (ed.) Bimanual Phaco: Mastering the Phakonit. SLACK, 2005

---

Tolosa-Hunt Syndrome (THS)

Definition

---

Historical Context

---

Anatomical Basis

Contents of Cavernous Sinus (affected in THS)

• CN III (oculomotor) - wall
• CN IV (trochlear) - wall
• CN V1 (ophthalmic division of trigeminal) - wall
• CN V2 (maxillary division) - wall (lower)
• CN VI (abducens) - within the sinus (most susceptible to pressure)
• Internal carotid artery + sympathetic plexus

Contents of Superior Orbital Fissure

• CN III, IV, VI, V1, superior ophthalmic vein, sympathetic fibers

---

Etiology and Pathology

• Idiopathic - unknown cause
• Pathology: Non-caseating granulomatous inflammation with fibrosis
• Histology: Lymphocytes, plasma cells, epithelioid cells, giant cells - similar to sarcoid granuloma
• The inflammation begins in the superior orbital fissure and may extend into the cavernous sinus or orbital apex
• Orbital venogram may show: occlusion of superior ophthalmic vein, partial obliteration of the cavernous sinus

---

Clinical Features

Cardinal Features (Classic Triad)

1. Severe, unilateral periorbital or hemicranial pain - boring/stabbing in character; precedes ophthalmoplegia by days-weeks
2. Painful ophthalmoplegia - paresis of CN III, IV, and/or VI
3. Dramatic response to corticosteroids

Detailed Features

Key Nerve Involvement Pattern

• CN III most common
• CN VI second most common (most vulnerable in cavernous sinus due to position)
• CN IV least commonly involved
• CN V1 sensory involvement very characteristic and helpful diagnostically
• All three ocular motor nerves can be involved = complete ophthalmoplegia

---

ICHD-3 Diagnostic Criteria (International Headache Society)

1. Unilateral headache fulfilling criterion 3
2. Both of the following:
   • Granulomatous inflammation of the cavernous sinus, superior orbital fissure, or orbit demonstrated by MRI or biopsy
   • Paresis of one or more of CN III, IV, and/or VI ipsilateral to the granulomatous inflammation
3. Evidence of causation demonstrated by:
   • Headache ipsilateral to the granulomatous inflammation
   • Headache preceding paresis by ≤2 weeks, or developing simultaneously
4. Not better accounted for by another ICHD-3 diagnosis
5. Response to corticosteroids (supports but not required for diagnosis)

---

Investigations / Workup

Imaging (Most Important)

• MRI with gadolinium (contrast) - Investigation of Choice
  • Coronal views with gadolinium infusion show lesion to best advantage
  • Findings: isointense to hypointense mass on T1; enhancing lesion in cavernous sinus/superior orbital fissure after gadolinium
  • May show thickening and enhancement of cavernous sinus wall
  • Can be normal in up to 30-40% of cases - negative MRI does not exclude THS
  • CT: less sensitive; may miss early or small lesions

Laboratory Tests (to exclude other causes)

• CBC, ESR, CRP - non-specific inflammation
• Serum ACE - exclude sarcoidosis
• ANCA (c-ANCA, p-ANCA) - exclude granulomatosis with polyangiitis
• ANA, ANCA, anti-dsDNA - exclude autoimmune/vasculitis
• Blood cultures - exclude infection
• Blood glucose, HbA1c - exclude diabetic oculomotor neuropathy
• FTA-ABS / VDRL - exclude syphilis
• Thyroid function - exclude thyroid orbitopathy

Other

• Orbital venography - may show superior ophthalmic vein occlusion, cavernous sinus narrowing
• Lumbar puncture - if meningitis/meningeal carcinomatosis suspected
• Biopsy - gold standard for definitive diagnosis; recommended in uncertain cases or when diagnosis is in doubt (especially to rule out malignancy)

---

Differential Diagnosis of Painful Ophthalmoplegia

Vascular

• Posterior communicating artery (PComA) aneurysm - CN III palsy with pupil involvement; urgent imaging needed
• Carotid-cavernous fistula - pulsatile proptosis, bruit, chemosis
• Cavernous sinus thrombosis - septic or aseptic; fever, toxicity
• Diabetic oculomotor mononeuropathy - pupil-sparing CN III; most common cause of isolated CN III palsy in adults
• Temporal (giant cell) arteritis - elderly, high ESR, jaw claudication
• Ophthalmoplegic migraine

Neoplastic

• Pituitary adenoma / apoplexy - sudden severe headache, visual field defects
• Parasellar meningioma - slow progressive
• Nasopharyngeal carcinoma - invading cavernous sinus
• Metastatic disease - dural metastases
• Lymphoma - can mimic THS on MRI

Inflammatory / Infectious

• Sarcoidosis - systemic features, serum ACE elevated
• Granulomatosis with polyangiitis (Wegener's) - c-ANCA positive
• Orbital pseudotumor (IOID) - similar but affects orbit more than cavernous sinus
• Herpes zoster ophthalmicus - vesicular rash, CN V1 distribution
• Mucormycosis - diabetic/immunocompromised; black eschar; rapidly progressive
• Tuberculous meningitis - multiple cranial nerve palsies, CSF changes

Vascular Structural

• Carotid aneurysm (intracavernous)
• Carotid-cavernous fistula

---

Treatment

First-Line: Systemic Corticosteroids

• Prednisone 60-100 mg/day orally (most sources: 60-80 mg/day)
• Wills Eye Manual protocol: 80-100 mg/day for 1 week, then taper by 10 mg/week
• Expected response: pain relief within 24-72 hours is characteristic and diagnostically supportive
• If pain persists after 72 hours - stop steroids and reinvestigate (likely not THS)
• Gradual taper over several weeks to months is required to prevent relapse
• Steroids should be continued for several weeks or longer (Adams & Victor)

Steroid-Sparing / Second-Line Agents (for relapsing/refractory disease)

• Azathioprine
• Methotrexate
• Mycophenolate mofetil
• Infliximab (TNF inhibitor - emerging evidence)
• Radiotherapy - reported in treatment-resistant cases

Important Caveats

• Other conditions (tumors, infections) may also initially respond to steroids, so close monitoring is mandatory
• Biopsy should be considered in uncertain cases or where secondary causes have not been excluded

---

Prognosis and Course

• Remissions and recurrences are characteristic
• Spontaneous resolution can occur
• Recurrence rate: ~23% (pooled from 456 cases - 2026 meta-analysis, PMID 41886124)
• Factors associated with higher recurrence risk: involvement of CN II, CN IV, and CN VI (multiple nerve involvement)
• Age, sex, and MRI findings did NOT predict recurrence in the meta-analysis
• Complete or near-complete recovery of ophthalmoplegia expected with treatment
• Persistent ophthalmoplegia is uncommon if treated early

---

Key Exam Points - High Yield Summary

---

• Kanski's Clinical Ophthalmology, 10th Ed. - Tolosa-Hunt Syndrome (orbital section)
• Adams and Victor's Principles of Neurology, 12th Ed. - Cavernous sinus syndrome and Tolosa-Hunt
• Wills Eye Manual - Treatment protocol
• KJ Lee's Essential Otolaryngology - Cranial polyneuropathy overview
• Kmeid & Medrea. "Review of Tolosa-Hunt Syndrome, Recent Updates." Curr Pain Headache Rep 2023 (PMID 38032539)
• da Luz & Silva. "Relapse in Tolosa-Hunt syndrome: meta-analysis of 456 cases." Neurol Sci 2026 (PMID 41886124) - recurrence rate 23%; CN II/IV/VI involvement predicts relapse