This 74-year-old male presents with a 2-month history of intermittent diplopia and ptosis of the left eye. Both eyes have limited elevation and the left eye has moderately limited abduction. A 25 PD esotropia and 10 PD left hypotropia are present. Pupils are equal. He reports that he is better in the morning and worse as the day goes on. He has undergone bilateral cataract surgery with IOL several years ago but is otherwise without any significant ocular history. What could be happening?