Abstract
Purpose:
This analysis investigated the impact of reducing central retinal thickness (CRT) on best corrected visual acuity (VA) and the relationship between CRT and VA gain in ranibizumab (RBZ) recipients with wet age-related macular degeneration in the EXCITE study
Methods:
Data from completers of the 12-month study were analysed. CRT and VA data from all patients (n=275) or a subgroup with baseline CRT ≥275 µm (n=179) treated monthly with 0.3 mg or quarterly with 0.3 or 0.5 mg RBZ were used. A linear regression model was used to describe the relationship between CRT and VA at month 12, or VA gain between baseline and month 12, or between CRT and VA changes between baseline and month 12. Patients were divided into five 50- µm strata of CRT at Month 12. Within each stratum, CRT change was determined and examined against VA gain
Results:
The linear regression model revealed no relationship between CRT and VA or VA gain at month 12, or change in CRT and VA between baseline and month 12 (R2 <0.05). Further analysis of stratified CRT at Month 12 showed an inversely proportional response between CRT at month 12 and improvement in CRT between baseline and Month 12 (from a median reduction of 127 µm for CRT ≤150 µm to a 32 µm increase for CRT >300 µm). In contrast VA gain from baseline was the highest (median=8 ETDRS letters) for the intermediate stratum 200-250 µm, compared with a median VA gain of 6 letters for the thinnest retina (CRT ≤150 µm) and 3 letters for the thickest retina (CRT >300 µm) at month 12. This effect was also seen when the analysis was restricted to the subgroup with a high baseline CRT ≥275 µm. Reduction in CRT at Month 12 was more pronounced in all strata for this subgroup with baseline CRT ≥275 µm, especially for the thinnest retina, and also inversely correlated with CRT at Month 12 (median reduction of 214, 172, 125, 76, and 2 µm for CRT ≤150 µm, 150 µm <CRT ≤200 µm, 200 µm <CRT ≤250 µm, 250 µm <CRT ≤300 µm, and 300 µm <CRT respectively), whereas VA gain was highest for the intermediate strata (median VA gain of 5, 8, 8, 4, and 3 letters, respectively)
Conclusions:
No linear correlation was found between VA gain and CRT at month 12. Further analysis of stratified CRT at Month 12 indicated that reducing CRT with RBZ was associated with improved VA gain up to a CRT threshold, below which further retinal thinning did not translate into further VA gain
Keywords: 412 age-related macular degeneration •
688 retina •
754 visual acuity