Best-corrected visual acuity (BCVA) time in range may accurately measure visual outcomes and and evaluate the consistency of treatment efficacy in individuals with diabetic macular edema (DME), according to a study published in Eye.
The investigation, which used post hoc data from the Diabetic Retinopathy Clinical Research (DRCR) Retina Network Protocol T trial (ClinicalTrials.gov Identifier: NCT01627249), included individuals with DME and a BCVA of 24 to 78 Early Treatment of Diabetic Retinopathy Study (ETDRS) letters (N=660). Participants underwent random assignment (1:1:1 ratio) to treatment with 2 mg intravitreal aflibercept (IVT-AFL), 1.25 mg intravitreal bevacizumab (IVT-BEV), or 0.3 mg intravitreal ranibizumab (IVT-RAN) every 4 weeks until achieving a BCVA of 84 ETDRS letters or better and central subfield thickness (CST) less than 250 mm, without any improvement or worsening following the most recent 2 injections.
The BCVA time in range analysis considered BCVA changes during 1 year with a BCVA threshold of 69 ETDRS letters (approximately 20/40 Snellen) or greater — a value corresponding to the legal BCVA values for driving in many countries.
A majority of the cohort (97.6%) underwent 7 or more BCVA assessments within 1 year and the average BCVA scores among the 3 treatment groups ranged between 64.5 and 65.1 ETDRS letters.
BCVA time in range varied according to anti-vascular endothelial growth factor (VEGF) treatment during the first year, the report shows. The time in range, after adjusting for baseline BCVA, was 41.2 (95% CI, 39.7-42.8) weeks for the IVT-AFL group, 37.2 (95% CI, 35.5-42.8) weeks for the IVT-BEV group, and 37.6 (95% CI, 35.9-39.3) weeks for the IVT-RAN group. Overall, participants treated with IVT-AFT spent 4.0 weeks longer in range compared with individuals treated with IVT-BEV (P =.002) and 3.6 weeks longer in range compared with patients treated with IVT-RAN (P =.004). IVT-BEV treatment was associated with a 0.4 weeks reduction in time in range compared with IVT-RAN treatment (P =.738).
At a higher threshold for BCVA (79 ETDRS letters or better), IVT-AFL was associated with 5.3 more weeks BCVA time in range compared with IVT-BEV (P =.001), and IVT-BEV was associated with 3.3 fewer weeks time in range compared with IVT-RAN (P =.045).
The BCVA time in range analysis could not differentiate between treatments with a BCVA threshold of 30 ETDRS letters, according to the report.
“[T]his analysis assesses the consistency of treatment efficacy above a predefined threshold over time, rather than a static measurement at the end of the trial,” according to the researchers. “This approach could be applied to either a treatment cohort to assess mean time in range or to an individual patient to monitor their treatment response. Time in range could also provide an additional or alternative approach for physicians when discussing clinical trial results with patients, by describing the number of weeks that an
individual given a specific treatment might expect to experience VA above a certain threshold.”
Study limitations include differences in the frequency of BCVA measurements among study participants, which may have affected BCVA time in range results.
Disclosure: This research was supported by Bayer Consumer Care AG. Some study authors declared affiliations with biotech, pharmaceutical, and/or device companies. Please see the original reference for a full list of authors’ disclosures.
Kozak I, Pearce I, Cheung CMG, et al. Visual acuity time in range: a novel concept to describe consistency in treatment response in diabetic macular oedema. Eye. Published online March 28, 2023. doi:10.1038/s41433-023-02507-x