Mucous membrane pemphigoidMucous membrane pemphigoid (MMP) refers to a heterogeneous group of autoimmune bullous disorders. The disease is characterized by recurrent inflammationInflammation and progressive scarringScarring that can affect all mucous membranes with varying frequencies. Ocular involvement presents the clinician with a diagnostic challenge as cicatricial conjunctivitis includes over 30 differential diagnosesDiagnosis, and specific diagnostic tests are negative in up to half of the cases. Fibrosis begins with minor changes such as subepithelial fibrosis, e.g. on the upper tarsal plate or next to the plica semilunaris. In the further course, fornix shortening or symblephara may develop. This can lead to entropion and trichiasis, possibly leading to chronic keratopathy with recurrent corneal erosionsCorneal erosion and vascularization. In the final stage, an ankyloblepharonAnkyloblepharon develops, possibly limiting all eyeEye movement (“frozen globe”). MMP is also a therapeutic challenge, as only very few randomized clinical trials have so far been performed due to the rarity of the disease. Patient management requires good collaboration with other specialties, the use of immunosuppressants and, only when inflammatory activity is under control, surgical rehabilitation. However, it is important to remember that seemingly trivial surgical procedures can trigger exacerbation of the disease and progression of fibrosis.