Fluctuating ptosis raises a neuromuscular-junction question

Ocular myasthenia can cause fluctuating ptosis even when antibody tests are negative, and requires focused clinical assessment.

Ocular myasthenia gravisNerve-muscle transmission failure can cause fatigable ptosis and binocular diplopia.
Cranial nerve palsy or orbital processA single ocular motor nerve or orbital problem may cause persistent misalignment.
Decompensated strabismusPrior latent eye misalignment may become symptomatic with illness or fatigue.
Thyroid eye diseaseExtraocular muscle inflammation or restriction can create double vision.
Brainstem or neurologic causeOther neurological findings can suggest central rather than ocular mechanisms.

Fatigable double vision may persist with a normal MRI

Eye-muscle fatigue can cause binocular misalignment without any lesion visible on routine structural imaging.

Cranial nerve palsy or orbital processA single ocular motor nerve or orbital problem may cause persistent misalignment.
Decompensated strabismusPrior latent eye misalignment may become symptomatic with illness or fatigue.
Thyroid eye diseaseExtraocular muscle inflammation or restriction can create double vision.
Brainstem or neurologic causeOther neurological findings can suggest central rather than ocular mechanisms.
Ocular myasthenia gravisNerve-muscle transmission failure can cause fatigable ptosis and binocular diplopia.

Fixed painful diplopia, unequal pupils or neurologic signs should not be attributed to a presumed benign condition.

Decompensated strabismusPrior latent eye misalignment may become symptomatic with illness or fatigue.
Thyroid eye diseaseExtraocular muscle inflammation or restriction can create double vision.
Brainstem or neurologic causeOther neurological findings can suggest central rather than ocular mechanisms.
Ocular myasthenia gravisNerve-muscle transmission failure can cause fatigable ptosis and binocular diplopia.
Cranial nerve palsy or orbital processA single ocular motor nerve or orbital problem may cause persistent misalignment.

Progressive swallowing, speech or respiratory weakness requires immediate clinical evaluation.

Thyroid eye diseaseExtraocular muscle inflammation or restriction can create double vision.
Brainstem or neurologic causeOther neurological findings can suggest central rather than ocular mechanisms.
Ocular myasthenia gravisNerve-muscle transmission failure can cause fatigable ptosis and binocular diplopia.
Cranial nerve palsy or orbital processA single ocular motor nerve or orbital problem may cause persistent misalignment.
Decompensated strabismusPrior latent eye misalignment may become symptomatic with illness or fatigue.