classification of myasthenia gravis

The most widely accepted classification of myasthenia gravis is the Myasthenia Gravis Foundation of America Clinical Classification:

Class I: Any eye muscle weakness, possible ptosis, no other evidence of muscle weakness elsewhere
Class II: Eye muscle weakness of any severity, mild weakness of other muscles
Class IIa: Predominantly limb or axial muscles
Class IIb: Predominantly bulbar and/or respiratory muscles
Class III: Eye muscle weakness of any severity, moderate weakness of other muscles
Class IIIa: Predominantly limb or axial muscles
Class IIIb: Predominantly bulbar and/or respiratory muscles
Class IV: Eye muscle weakness of any severity, severe weakness of other muscles
Class IVa: Predominantly limb or axial muscles
Class IVb: Predominantly bulbar and/or respiratory muscles (Can also include feeding tube without intubation)
Class V: Intubation needed to maintain airway