Factors associated with the response to fluocinolone acetonide 0.19 mg in diabetic macular oedema evaluated as the area-under-the-curve

Objectives: The area-under-the-curve (AUC) measures the average drug effect over time. We investigated the impact of baseline clinical and optical coherence tomography (OCT) factors on the response to fluocinolone acetonide (FAc) 0.19 mg implant in patients with diabetic macular oedema (DMO) as the AUC over 36 months. Methods: Retrospective study of DMO eyes undergoing FAc with follow-up from 12 to 36 months. The AUC of the best-corrected visual acuity (BCVA) and the central macular thickness (CMT) were calculated with the trapezoidal rule. Demographic and clinical data at the time of FAc administration were collected, and associations with BCVA and CMT changes were investigated with linear mixed models. Results: Eighty-nine eyes of 63 patients were enroled; median follow-up was 26 months. Mean±standard deviation (SD) AUCBCVA and AUCCMT after FAc injection were 0.24 ± 0.17 LogMAR/month and 179.6 ± 54.3 μm/month, respectively. Worse baseline BCVA (β = 0.30 LogMAR/month, p < 0.001), higher AUCCMT after FAc administration (β = 0.08 LogMAR/month, p < 0.001), diagnosis of type 1 diabetes (β = −0.04 LogMAR/month, p = 0.04), and absent ELM/EZ layers (β = 0.06 LogMAR/month, p = 0.01) were associated with worse vision over time (higher AUCBCVA). Eyes with higher CMT at baseline (β = 9.61 μm/month, p < 0.001) and those with tractional DMO (β = 24.7 μm/month, p = 0.01) had worse anatomic outcomes (higher AUCCMT). The need for additional treatments after FAc was also associated with higher AUCCMT (β = 33.9 μm/month, p = 0.001). Conclusion: Baseline better visual acuity, lower macular thickness, and photoreceptors’ layers integrity are associated with better functional response to FAc in DMO. Eyes with severe DMO at the time of implant or tractional oedema have worse anatomic response. These findings might guide clinicians in a more informed decisional algorithm in treating DMO.