Neuro-Ophthalmic
Myasthenia Gravis
Also known as: myasthenia gravis, ocular myasthenia, MG, variable diplopia, fatigable ptosis, ice pack test
Filed as: Urgent
Source-cited from the record's own evidence list. Clinical content programme led by Dr Ankit Mathur, PhD, Grad Cert Ocu Thera, B.S. Optom. How the clinical content is governed
Clinical decision support only
Overview
An autoimmune disorder of neuromuscular transmission that shows in the eye as fatigable ptosis and variable double vision, changing through the day and even through the consultation. The misalignment does not settle into a single cranial nerve pattern, and the lid droops further with sustained upgaze. Difficulty with swallowing, speech or breathing alongside the eye signs is a medical emergency rather than an ocular one.
Recognition
Symptoms: what patients report
- Intermittent or variable binocular diplopia that may change during the day.
- Ptosis that worsens with fatigue and may vary during the consultation.
- Symptoms are not fixed to one single cranial nerve pattern.
- Bulbar or respiratory symptoms indicate systemic myasthenia risk and require emergency escalation.
Signs: what the examination shows
- Variable ocular misalignment or fluctuating motility limitation.
- Fatigable ptosis; Cogan lid twitch may be present.
- Improvement after ice-pack testing supports the pattern where available.
- Pupils are typically normal in myasthenia; any pupil abnormality should prompt assessment for another cause, such as a third nerve palsy.
What OptoGuide™ covers for myasthenia gravis
- Pattern reasoning: what this combination of findings points to, and its differentiators
- Don't-miss risks and escalation triggers
- Management tiers with linked New Zealand therapeutics
- Referral urgency, specialty, and letter drafting
Sources
- Myasthenia Gravis — EyeWiki
- The Neuro-Ophthalmology Survival Guide (Pane, Miller & Burdon) — standard reference text
- Clinical Reasoning: An 83-Year-Old Female Patient With a Pupil-Involving Oculomotor Nerve Palsy. Riegel DC, Jauregui R, Dugue A. Neurology. 2025;105(12):e214383.
- Incidence and Etiologies of Acquired Third Nerve Palsy Using a Population-Based Method. Fang C, Leavitt JA, Hodge DO, et al. JAMA Ophthalmology. 2017;135(1):23-28.
- Clinical Reasoning: An Unusual Cause of Diplopia and Ptosis in a 67-Year-Old Woman. Bireley JD, Santucci J, Li Y, Cohen DA. Neurology. 2023;101(16):e1646-e1651.
- Adult Strabismus Preferred Practice Pattern. Dagi LR, Velez FG, Holmes JM, et al. Ophthalmology. 2024;131(4):P304-P401.
- Clinical and imaging clues to the diagnosis and follow-up of ptosis and ophthalmoparesis. Keene KR, Kan HE, van der Meeren S, et al. J Cachexia Sarcopenia Muscle. 2022;13(6):2820-2834.
Standard texts: Kanski's Clinical Ophthalmology: A Systematic Approach, Oxford Handbook of Ophthalmology, Oxford American Handbook of Ophthalmology, Signs in Ophthalmology: Causes & Differential Diagnosis.