Ophthalmology & Neurology & Internal Medicine
Névrite optique | Clinique Omicron Québec
Optic neuritis is an acute inflammation of the optic nerve - the second cranial pair - resulting in unilateral visual impairment of subacute onset (within hours to days), characteristically associated with retroorbital or periorbital pain accentuated by eye movements, and ipsilateral relative pupillary afferent deficit (DPAR, Marcus Gunn sign). It is the first clinical manifestation of multiple sclerosis (MS) in around 20 to 25 % of patients who go on to develop the disease, and occurs during the course of MS in 50 to 70 % of confirmed MS patients. The risk of developing MS after a first episode of isolated optic neuritis depends directly on the number of white matter lesions detected on brain MRI during the initial work-up: in the presence of MRI lesions characteristic of MS, the risk is 50 to 75 % at 15 years (ONTT study - Optic Neuritis Treatment Trial), while a normal brain MRI reduces this risk to around 25 % at 15 years. The most common form - retrobulbar optic neuritis (NORB) - is not accompanied by any visible abnormality on fundus examination at the time of the acute episode (as the inflammation is located in the intracanal or intraorbital portion of the nerve, behind the papilla), giving rise to the classic ophthalmological aphorism: «the doctor sees nothing, the patient sees nothing». The visual prognosis of typical demyelinating optic neuritis is generally favourable, with spontaneous recovery of visual acuity to 20/40 or better in over 90 % of cases within 6 to 12 months, although normal acuity may mask subtle functional sequelae (reduced contrast sensitivity, residual dyschromatopsia, Uhthoff phenomenon). Atypical forms - bilateral, severe, without recovery, or with anti-AQP4 or anti-MOG antibodies - require specific management distinct from MS-associated optic neuritis.
Pathophysiology and classification
- Demyelinating optic neuritis (MS-associated or CIS): inflammation and focal demyelination of optic nerve fibers by autoreactive T lymphocytes → slowing of nerve conduction → vision loss + altered color vision + the mechanism is identical to that of MS plaques in the rest of the central nervous system + after the acute episode → partial remyelination → functional recovery in the majority of cases + unmyelinated axons may persist but undergo progressive atrophy (atrophy of the retinal nerve fiber layer — RNFL — measurable by OCT)
- Optic neuritis with anti-AQP4 antibodies (NMOSD — Neuromyelitis Optica Spectrum Disorder): Antibodies IgG anti-aquaporin-4 (AQP4-IgG) directed against pericapillary astrocytic end-feet → astrocytic necrosis + severe inflammation + irreversible axonal damage → simultaneous or relapsing bilateral optic neuritis + severe vision loss with poor recovery + often associated with longitudinally extensive transverse myelitis + different profile from MS → specific immunosuppressive treatment (azathioprine + mycophenolate + rituximab + inebilizumab + satralizumab)
- Optic neuritis with anti-MOG antibodies (MOGAD — MOG Antibody Associated Disease): IgG anti-MOG (Myelin Oligodendrocyte Glycoprotein) antibodies → optic neuritis often bilateral + papillitis (papilledema visible on FO) + relapsing + clinical profile distinct from MS and NMOSD + response to corticosteroids generally good but frequent relapses on regression → maintenance of immunosuppressive therapy if relapses.
- Non-demyelinating optic neuritis Sarcoidosis (granulomatous optic neuritis + elevated ACE + lung lesions) + infectious diseases (syphilis + Lyme disease + bartonellosis + tuberculosis + HIV) + systemic lupus erythematosus + Sjögren's syndrome + acute anterior ischemic optic neuropathy (AAION - to be distinguished from inflammatory optic neuritis: no pain + sudden altitudinal vision loss + older patient + cardiovascular risk factors) + tumor compression of the optic nerve (optic nerve sheath meningioma + craniopharyngioma)
Clinical Presentation — Characteristic Signs
| Clinical sign | Detailed description | Diagnostic value |
|---|---|---|
| Unilateral visual loss | Subacute onset within hours to days (maximum 1-2 weeks) + variable degrees: mild blurred vision to light perception only + unilateral in the typical form associated with MS (bilateral → consider NMOSD or MOGAD) + worsening with heat or exertion (Uhthoff's phenomenon) starting in the acute phase | Present in 100 % of cases, the speed of installation and unilateral character distinguish optic neuritis from amblyopia or chronic retinopathy. |
| Retro-orbital pain | Retro-orbital or peri-orbital pain, characteristically worsened by eye movements (pain on ocular movement), precedes or accompanies visual loss, and is present in 90-95% % of MS-associated optic neuritis. | Highly characteristic — pain on eye movement associated with decreased vision is almost pathognomonic of inflammatory optic neuritis + absence of pain → consider NAION or compression |
| Relative Afferent Pupillary Defect (RAPD — Marcus Gunn pupil) | Paradoxical pupillary response to alternating illumination of both eyes (swinging flashlight test) → the light stimulus applied to the affected eye causes relative pupillary dilation (instead of normal constriction) → indicates asymmetry in afferent nerve conduction between the two eyes | Présent dans > 95 % des névrites optiques unilatérales + signe objectif crucial car il confirme une atteinte du nerf optique (et non une cause maculaire ou rétinienne bilatérale) + peut persister après récupération visuelle complète comme séquelle subclinique |
| Dyschromatopsia (color vision deficiency) | Reduced color saturation and vividness in the affected eye + red perceived as pink or brown (red desaturation) + Farnsworth-Munsell 100 hue test or Ishihara plates for quantification + may persist as a sequela after visual acuity recovery | Highly sensitive functional symptom indicating damage to the fibers processing chromatic information + can be the first subjective symptom noticed + useful for screening during follow-up |
| Fundus | Normal in retrobulbar optic neuritis (RON — 65 to 70 % of MS-associated cases) → inflammation behind the optic disc not visible + Papillitis (ipsilateral optic disc edema) in 30 to 35 % of cases + peripapillary hemorrhages and exudates → rare in demyelinating optic neuritis → if present: consider an infectious cause or stasis optic disc edema | A normal fundus examination does not rule out optic neuritis — NORB is the most frequent form in the context of MS + papillitis is more frequent in MOGAD and infectious causes |
| Uhthoff's phenomenon | Transient worsening of vision or reappearance of symptoms with an increase in body temperature (physical exercise + hot bath + fever + sun exposure) → related to the sensitivity of demyelinated fibers to temperature variations (temperature-dependent conduction block) + completely reversible upon return to normal temperature | Pathognomonic for a demyelinating lesion of the optic nerve + may persist for years after the initial episode + diagnostically useful in subacute or atypical forms |
ℹ️
Optic neuritis is a neurological and ophthalmological emergency that should be evaluated within 24 to 48 hours of symptom onset. Urgent brain MRI is essential—not only to confirm the diagnosis but above all to quantify the risk of conversion to multiple sclerosis and to decide on the initiation of disease-modifying immunotherapy. An incomplete assessment delaying this diagnosis deprives the patient of an important therapeutic window for the prevention of demyelinating relapses.
Diagnostic assessment
- Brain and orbital MRI with gadolinium — key examination: Brain MRI with FLAIR + T2 + T1 with gadolinium + orbital sequences with fat saturation (STIR or fat-sat T2) → enhancement of the optic nerve after gadolinium confirms active inflammation + periventricular white matter lesions + juxtacortical + infratentorial on T2/FLAIR → allow classification of MS risk according to McDonald criteria 2017 + an MRI of the brain with ≥ 2 characteristic lesions = clinically isolated syndrome (CIS) at high risk of MS (50–75 % at 15 years according to the ONTT study)
- OCT (Optical Coherence Tomography) measurement of peripapillary retinal nerve fiber layer (RNFL) thickness and macular thickness + acute phase RNFL edema (if papillitis) → progressive RNFL thinning (optic atrophy) in the months following the episode → marker of neurodegeneration and irreversible axonal damage + tool for monitoring long-term visual prognosis
- Visual Evoked Potentials (VEP) EEG recording of cortical responses to checkerboard visual stimulation + P100 wave latency prolongation (demyelinated optic nerve conduction delay) → confirms optic nerve involvement + can be abnormal even after complete visual recovery (persistent prolonged latency) → value in subacute or subclinical forms + useful for documenting a second subclinical episode
- Anti-AQP4 (anti-aquaporin-4) and anti-MOG antibodies: Systematic blood count before any optic neuritis + essential workup to classify the etiological spectrum + positive anti-AQP4 → NMOSD → specific immunosuppressive treatment + positive anti-MOG → MOGAD → management distinct from MS + both antibodies negative + typical MRI lesions → MS-associated optic neuritis or CIS
- CSF (lumbar puncture) results: not systematic in typical optic neuritis + indicated if diagnostic doubt + or incomplete MS assessment + oligoclonal bands in CSF present in 80 to 90 % of confirmed MS + elevated IgG index + if infectious or granulomatous meningitis suspected
- Assessment of non-demyelinating causes if atypical form: ECA (sarcoidosis) + syphilis serology + Lyme + bartonellosis + HIV + tuberculosis + ANA + anti-dsDNA (lupus) + anti-SSA/SSB (Sjogren) + CBC + blood glucose + kidney panel + liver panel
Treatment and prognosis
| Therapeutic aspect | Protocol and terms | Evidence and remarks |
|---|---|---|
| Methylprednisolone IV - acute treatment | Methylprednisolone 1 g IV daily for 3 days, followed by optional oral prednisone (1 mg/kg daily for 11 days with a taper) + to be initiated within 2 weeks of symptom onset for maximum benefit | ONTT study (Beck 1992 — JAMA): accelerates visual recovery (faster return to normal acuity by 2-4 weeks) + does not change final visual acuity at 1 year + reduces by 50 % the risk of a second demyelinating event at 2 years (transient benefit) + oral prednisone alone (without IV) is associated with a higher relapse rate in the ONTT study → do not use oral corticosteroids alone for optic neuritis |
| Disease-modifying therapy (MS / CIS) | Initiation of disease-modifying therapy for MS is recommended from the first episode (CIS) if the brain MRI is abnormal (> 1 characteristic T2 lesion) + first-line medications: interferon beta-1a + interferon beta-1b + glatiramer acetate + dimethyl fumarate + teriflunomide + highly effective medications if poor prognostic factors: natalizumab + ocrelizumab + alemtuzumab | CHAMP study (Jacobs 2000 — NEJM) + ETOMS + BENEFIT: disease-modifying treatment starting at CIS reduces the conversion to clinically definite MS by 30% to 50% % at 2 years + improves long-term prognosis + shared decision-making with the patient after discussing the benefit/risk ratio + mandatory follow-up by an MS-specialized neurologist |
| NMOSD Specific Treatment (anti-AQP4+) | Maintenance immunosuppressive therapy from the first episode: azathioprine 2–3 mg/kg/day + or mycophenolate mofetil 1–3 g/day + or rituximab (anti-CD20) 375 mg/m² × 4 doses or 1,000 mg × 2 doses + new approved therapies: inebilizumab (Uplizna®) + satralizumab (Enspryng®) + eculizumab (Soliris®) for severe anti-AQP4+ NMOSD + MS maintenance treatments (natalizumab + fingolimod) can worsen NMOSD → to be strictly avoided | La NMOSD non traitée entraîne des rechutes sévères avec perte visuelle cumulative irréversible et handicap progressif + les nouvelles biothérapies anti-CD19 + anti-IL-6R ont démontré une réduction de > 90 % des rechutes dans les essais pivots (N-MOmentum + SAkuraSky + PREVENT) |
| MOGAD treatment (anti-MOG+) | Acute phase: methylprednisolone IV 1 g x 3–5 days + IVIG if corticosteroid resistance + maintenance if frequent relapses: oral corticosteroids + monthly IVIG + rituximab + mycophenolate + slow tapering of corticosteroids is essential (risk of relapse if stopped abruptly) | MOGAD generally responds well to corticosteroids but frequently relapses upon tapering, often requiring maintenance treatment. Unlike NMOSD, established MS therapies are not formally contraindicated, but their efficacy is insufficiently documented. |
| Visual prognosis | Spontaneous recovery expected in 90 % of typical demyelinating optic neuritis + visual acuity ≥ 20/40 in > 90 % at 1 year + 20/20 acuity recovered in 70–75 % + frequent subclinical sequelae despite normal acuity: residual dyschromatopsia + reduced contrast sensitivity + visual field deficit + persistent Uhthoff's phenomenon | Poor visual prognostic factors: very low visual acuity ( 20 µm at 6 months) predicts long-term functional sequelae |
Situations requiring urgent evaluation within 24 to 48 hours
Any acute or subacute unilateral visual loss associated with retro-orbital pain that is worsened by eye movements must be urgently evaluated by an ophthalmologist and a neurologist within 24 to 48 hours. The diagnosis of optic neuritis should be made quickly to initiate IV corticosteroids, which accelerate recovery, perform brain MRI to assess the risk of MS, and measure anti-AQP4 antibodies to identify NMOSD forms requiring urgent immunosuppressive treatment to prevent relapses with irreversible vision loss.
A simultaneous bilateral visual penurunan, with or without pain, with or without recovery at 4 to 6 weeks, with or without positive anti-AQP4 antibodies, are warning signs requiring urgent neurological management, as they suggest NMOSD, whose severity and risk of disabling relapses far exceed those of typical MS-associated optic neuritis.
For the evaluation of acute visual loss, brain and orbital MRI prescription, anti-AQP4 and anti-MOG antibody testing, and referral to ophthalmology and neurology, Clinique Omicron offers medical consultations at its service points in Quebec and via telemedicine. To book an appointment, visit cliniqueomicron.ca.
Consult at Clinique Omicron
Clinique Omicron's nurse practitioners (NPs) recognize the characteristic symptoms of optic neuritis (unilateral vision loss + retro-orbital pain + relative afferent pupillary defect), order urgent brain and orbital MRI, initiate requests for anti-AQP4 and anti-MOG antibody testing, and urgently refer patients to ophthalmology and neurology for diagnostic confirmation, initiation of IV corticosteroids, and discussion of disease-modifying immunotherapy. Consultations are available at several service locations in Quebec and via telemedicine. To book an appointment, visit cliniqueomicron.ca.
The content of this page is for informational purposes only and is not a substitute for the advice of an ophthalmologist or neurologist. Optic neuritis is a neurological and ophthalmological emergency requiring specialized evaluation within 24 to 48 hours for diagnosis, treatment initiation, and assessment of the risk of multiple sclerosis or NMOSD.
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