The effect of real-world follow up delay between planned intravitreal anti-VEGF treatments for neovascular age- related macular degeneration on retinal thickness

Purpose: To study the impact of real-world follow-up delay on anatomical outcomes for age-related macular degeneration (AMD) treated with intravitreal injection. Methods: A retrospective, sequential, observational cohort analysis of the Whangārei Hospital retinal clinic was conducted between Aug 2021 – Dec 2021. Planned follow-up time on treat and extend (T&E) protocol was compared with actual follow-up injection time. OCT Central Subfield Thickness (CST) measurements were compared between treatment reviews for each patient. Results: The mean delay from planned injection for patients receiving intravitreal injection (n=709) was 6.51 days [SD = 13.88]. Eyes that received an intravitreal injection within 7 days of their planned treatment date prior to clinical review (n=209) had a mean reduction of their CST [-5.74mm ± 2.84mm]. Eyes that received treatment later than 7 days from their planned treatment date prior to clinical review (n=152) had a mean increase in the CST [9.03mm ± 4.33mm]. We established a time-dependent correlation between increased delay (in weeks) and CST. Conclusion: A delay greater than 7 days from planned injection was associated with a statistically significant increase in the CST in patients with AMD. It also indicates the importance of adherence to recommended follow-up timeframes when following T&E protocol.