Smoking Exacerbates Myasthenia Gravis Progression

Smoking was identified as an additional risk factor that not only increases the probability of conversion to generalized MG but also accelerates the conversion timeline. Emphasizing the importance of smoking cessation could substantially ameliorate ocular MG symptoms and mitigate the risk of conversion to generalized MG. Photo: Dennis Mathews, OD. Click image to enlarge. Myasthenia gravis (MG) is an autoimmune condition that results from autoantibodies targeting the neuromuscular junction, leading to impaired neuromuscular transmission, muscle weakness and fatigue. Those with only ocular symptoms at presentation are at risk of conversion to generalized myasthenia gravis. The conversion rate of ocular to generalized MG lacks definitive predictors. Over a 13-year follow-up period, researchers in Thailand evaluated the risk and protective factors associated with the conversion of ocular MG to generalized MG to identify the factors influencing the time to conversion. Their analysis indicated a conversion rate of 25.5% at two years after onset and highlighted thymic abnormalities and positive acetylcholine receptor antibody (AChR Ab) results as substantial risk factors for conversion.This retrospective cohort study analyzed data collected from 200 ocular MG patients, and both AChR Ab-positive and -negative patients were included. Over 60% of participants were female, which was consistent across the ocular MG (61.5%) and generalized MG (67.9%) groups. The mean age at onset of ocular MG was 49.2 years, with 48.4 years in the ocular MG group and 50.44 years in the generalized group.The researchers found that 39% developed generalized MG, with a median conversion time of 16 months and a two-year conversion rate of 25.5%. AChR Ab positivity (adjusted hazard ratio; HR: 2.88), thymic abnormalities (adjusted HR: 2.30), smoking (adjusted HR: 1.78) and pyridostigmine dosages greater than 180mg/day (adjusted HR: 2.33) were significantly associated with shorter conversion time.“This association is predicated on the hypothesis that the pathophysiology of myasthenia gravis involves an abnormal thymus that produces AChR Ab,” the study authors wrote in their paper, which was published in Journal of Ophthalmology. “Therefore, chest imaging and testing for anti-AXhR Ab should be conducted for all patients diagnosed with ocular MG.”The team did note that, given the established link between smoking and an increased risk of more severe ophthalmopathy in Graves’ disease, it is plausible that smoking may influence the pathogenesis of ocular MG. Due to the coexistence of Graves’ disease and ocular MG, smoking might exacerbate ocular symptoms in ocular MG patients.The use of an immunosuppressive agent, specifically oral prednisolone, appeared to offer a protective effect against generalization in patients with ocular MG. Therefore, patients should be comprehensively counseled on the risks and benefits of immunosuppressive therapy as an effective strategy to lower the conversion rate to generalized MG. Future research efforts should be directed toward executing randomized controlled trials or prospective studies to substantiate our findings. Click here for the journal source. Chuenkongkaew W, Chirapapaisan N, Chatchutimakorn P, et al. Factors influencing the conversion of ocular myasthenia gravis to generalized myasthenia gravis: a retrospective cohort study. J Ophthalmol. 2026;2026:6652248. This article was developed by the editorial staff in conjunction with experts in the field. In the process, AI may have been among the editorial tools used to meet the goals of human editors, who approved all content.