Time to fellow eye involvement in patients with unilateral diabetic macular oedema

Objective To examine the time to onset of disease in the fellow eye of patients with unilateral DMO in routine clinical practice and to identify risk factors for development of bilateral DMO. Design Retrospective cohort study. Participants One hundred forty treatment-naive patients 18 years or older with unilateral DMO presenting to Cole Eye Institute between January 2012 and July 2021. Methods Records of patients with unilateral DMO were reviewed for development of DMO in the fellow eye. Demographic, diabetic, ocular, and systemic characteristics were collected at initial DMO diagnosis date. Bivariate and multivariate analyses were performed and significant factors were modelled using Kaplan-Meier curves. Results Fifty patients with conversion to bilateral DMO and 90 patients without conversion were identified. Average time to bilateral DMO was 15.0 ± 15.7 months. 64% of patients converted within 1 year and 90% converted within 3 years. HbA1c ( p = 0.003), diabetic retinopathy duration ( p = 0.029), and diabetic foot disease (DFD) ( p = 0.002) were identified as significant risk factors for conversion. Patients with better visual acuity at time of initial diagnosis and history of panretinal photocoagulation (PRP) ( p = 0.044) or focal laser ( p = 0.035) in the primary eye were also more likely to convert. Conclusions Participants were most likely to develop fellow eye DMO within the first year after initial DMO diagnosis. In routine clinical practice, poor glycaemic control and DFD were risk factors associated with bilateral eye involvement. Clinicians may consider screening the fellow eye of high-risk individuals at each appointment within the first year of diagnosis.