Ocular myasthenia gravis - How effective is low dose prednisone long term?

Abstract

Introduction: Controversy persists on the best treatment to control ocular myasthenia gravis (OMG) and reduce conversion to generalized myasthenia gravis (GMG). We hypothesized that low dose prednisone could accomplish both in a cohort of OMG patients followed after three years.

Methods: We reviewed the records of 168 patients who presented with OMG. Our study included 103 of the OMG patients who met inclusion criteria, requiring follow up for a minimum of 3 years without disease generalization. Low dose prednisone was defined as ≤7.5 mg per day. The main outcome was having single vision without ptosis blocking vision, measured by binocular single vision (BSV) and upper lid position. We also analyzed late progression to GMG.

Results: Of 87 patients treated with prednisone, chronic low dose prednisone alone restored BSV in 47 patients (46% of all patients) without GMG. Pyridostigmine monotherapy restored BSV in 11/14 patients (11% of all patients). Other immunomodulatory therapy (OIT) was needed in 38 patients (37%). Medical therapy maintained BSV at last evaluation (mean follow up 8.2 ± 5.0 years) in 93 patients (90%). GMG developed in 10 patients (10%) during the follow-up period.

Conclusion: In OMG patients who do not generalize before 3 years, chronic long term prednisone at lower doses is moderately effective in maintaining optimum BSV. However, OIT are commonly required in these patients. In these OMG patients receiving prednisone and/or OIT, conversion to GMG after three years of disease is uncommon.

Keywords: Binocular single vision; Generalized myasthenia gravis; Ocular myasthenia gravis; Other immunomodulatory therapy; Prednisone.