Treatment of ocular symptoms in myasthenia gravis

The choice between acetyl-cholinesterase inhibitors (AChE-Is) and steroids as symptomatic therapy for ocular symptoms in myasthenia is controversial.

Thirty-five patients with myasthenia and ocular symptoms were evaluated by a single investigator. The ocular-quantitative myasthenia gravis (QMG) score was determined at each visit. The longitudinal construct validity of the ocular-QMG was assessed. Treatment epochs on AChE-I therapy alone or on steroids were defined for each patient. Changes in ocular-QMG scores between the start and end of each treatment epoch as well as the proportion of subjects achieving remission of symptoms were documented. The frequency of steroid-induced side effects was documented.

The longitudinal construct validity was favorable and comparable to that for the total QMG score. Eight patients were treated with AChE-I therapy alone, 6 were initially treated with AChE-I followed by steroids, and 21 received steroids ab initio. There were 14 epochs of AChE-I treatment and 27 epochs of steroid treatment. The mean improvement in ocular-QMG score was greater during the steroid epoch (3.6 +/- 2.4) than during the AChE-I epoch (1.1 +/- 1.9) (p = 0.0021). Complete resolution of ocular symptoms occurred in 29% of AChE-I treatment epochs and in 70% of steroid treatment epochs. The most common steroid-induced side effects observed were impaired glucose tolerance (67%) and reduced bone mineral density (20%).

The ocular-quantitative myasthenia gravis score may be a useful tool for monitoring ocular symptom severity in myasthenia. Steroids appear to be more effective than acetyl-cholinesterase inhibitors. These findings warrant a more formal evaluation in a randomized controlled trial.