Anti-Acetylcholine Receptor antibodies in Tear for the Diagnosis of Ocular Myasthenia Gravis.

BACKGROUND AND OBJECTIVE Ocular myasthenia gravis (OMG) significantly affects patients' quality of life. However, conventional serum assays often fail to detect anti-acetylcholine receptor (AChR) antibodies in more than half of OMG cases, complicating accurate diagnosis. Given the immunological role of tears in the ocular environment, they may serve as a viable alternative for antibody detection. This study investigates the utility of tear-based anti-AChR antibody detection as a diagnostic tool for OMG and compares its performance with that of serum-based cell-based assays (CBAs). DESIGN Prospective diagnostic testing validity evaluation. METHODS A total of 65 participants were enrolled, including 52 patients diagnosed with OMG and 13 healthy controls. Anti-AChR antibodies were assessed in both serum and tear samples using CBAs. Diagnostic performance metrics were compared between the two sample types, and correlations between antibody levels and clinical severity were analyzed. RESULTS Tear-based CBA demonstrated significantly superior diagnostic accuracy (AUC = 0.926, P < 0.0001) compared to serum-based CBA (AUC = 0.656, P = 0.0836). The sensitivity of tear CBA was 80.8% (95% CI: 68.1%-89.2%), markedly higher than that of serum CBA at 42.3% (95% CI: 29.9%-55.8%). Among the 42 seronegative OMG patients, 83.3% tested positive using tear CBA, whereas only 40.5% were positive via serum CBA (P < 0.0001). Notably, tear anti-AChR antibody levels did not show a consistent correlation with symptom severity. CONCLUSIONS Tear-based detection of anti-AChR antibodies offers a non-invasive, highly sensitive diagnostic approach for OMG, particularly beneficial in cases where serum tests are negative. This method holds promise for improving early diagnosis and clinical decision-making in OMG management.