Clinical implications of serum IgG levels in patients with IgG-related ophthalmic disease.

Aims: The present study aimed to investigate the clinical implications of serum IgG levels in patients with IgG-related ophthalmic disease (ROD).

Methods: The medical records of 31 patients who met the diagnostic criteria for IgG-ROD were retrospectively reviewed. Twenty-five patients whose serum IgG levels could be identified were included. Clinical manifestations and serum IgG levels before and after corticosteroid treatment were obtained. Factors associated with relapse were evaluated by comparing the features of patients with disease relapse with those of patients without relapse.

Results: Twenty-four patients were 'definite' and one was 'probable' for IgG-ROD according to the diagnostic criteria. Serum IgG levels were higher in patients with systemic involvement (p=0.046). All patients improved clinically after corticosteroid treatment. Serum IgG levels decreased after steroid treatment (p=0.005) and normalised in nine patients. In cases of relapse, serum IgG levels increased along with the aggravation of symptoms (p=0.047). Serum IgG levels that were still elevated (≥135 mg/dL) after steroid treatment (p=0.034) and cessation of steroid treatment during disease remission (p=0.043) were predictive factors for IgG-ROD relapse.

Conclusions: Serum IgG level can be considered an adjunctive marker for treatment response in IgG-ROD. Patients with serum IgG levels that remain elevated after steroid treatment should be carefully observed for relapse. A continuing maintenance dose of oral steroid is recommended to prevent relapse, even when clinical remission is achieved.