P038 Is it all in the eyes?

Abstract Background/Aims The ocular manifestations of giant cell arteritis (GCA) and ocular myasthenia gravis (OMG) have significant overlap, which can lead to clinical uncertainty in the absence of awareness and routine diagnostic testing. Methods We present the case of a 63-year-old male patient with a strong family history of autoimmune disease. He presented to the Rheumatology department in 2009 with symptoms of polymyalgia rheumatica (PMR) and was treated successfully with a reducing regime of Prednisolone. In 2013, he presented to the Ophthalmology department with blurred vision and diplopia. Giant cell arteritis was suspected and a high dose of Prednisolone was started. His temporal artery biopsy was normal and inflammatory markers were not raised, but there was a complete resolution of his symptoms since starting steroids. Under the care of the Rheumatology department, reducing regimes of Prednisolone were attempted and a steroid sparing agent, Methotrexate was introduced. Unfortunately, he continued to have recurring symptoms of blurred vision and diplopia, particularly at Prednisolone doses less than 20mg. Over the course of a few years, there was a progression of his ocular symptoms. He developed a horizontal diplopia, monocular ptosis and a 4th nerve palsy. He was referred back to the Ophthalmology department, where alternate diagnoses were investigated. Anti-acetylcholine receptor antibodies (AChR) were strongly positive at 35 mU/L (normal