Visual acuity time in range: a novel concept to describe consistency in treatment response in diabetic macular oedema
Igor Kozak, Ian Pearce, Chui Ming Gemmy Cheung, Tobias Machewitz, George N. Lambrou, Daniel Molina, Lima Suleiman, Hossam Youssef, Neil M. Bressler
Abstract
OBJECTIVE: To assess 'time in range' as a novel measure of treatment response in diabetic macular oedema (DMO). METHODS: This post hoc analysis of the Protocol T randomised clinical trial included 660 individuals with centre-involved DMO and best-corrected visual acuity (BCVA) letter score ≤78-≥24 (approximate Snellen equivalent 20/32-20/320). Study participants received intravitreal aflibercept 2.0 mg, repackaged (compounded) bevacizumab 1.25 mg, or ranibizumab 0.3 mg given up to every 4 weeks using defined retreatment criteria. Mean time in range was calculated using a BCVA letter score threshold of ≥69 (20/40 or better; minimum driving requirement in many regions), with sensitivity analyses using BCVA thresholds from 100 to 0 (20/10 to 20/800) in 1-letter increments. RESULTS: Time in range was defined as either the absolute or relative duration above a predefined BCVA threshold, measured in weeks or as a percentage of time, respectively. Using a BCVA letter score threshold of ≥69 (20/40 or better), the least squares mean time in range (adjusted for baseline BCVA) in Year 1 was 41.2 weeks with intravitreal aflibercept, 4.0 weeks longer (95% CI: 1.7, 6.3; p = 0.002) than bevacizumab and 3.6 weeks longer (1.3, 5.9; p = 0.004) than ranibizumab. Overall, mean time in range was numerically longer for intravitreal aflibercept for all BCVA letter score thresholds between 92 and 30 (20/20 to 20/250). In the Day 365-728 analysis, time in range was 3.9 (1.3, 6.5) and 2.4 (0.0, 4.9) weeks longer with intravitreal aflibercept vs bevacizumab and vs ranibizumab (p = 0.011 and 0.106), respectively. CONCLUSION: BCVA time in range may represent another way to describe visual outcomes and potential impact on vision-related functions over time for patients with DMO and provide a better understanding, for physicians and patients, of the consistency of treatment efficacy.