CRT, Vision Loss Have Complex Relationship

by: Amanda Warren
A retrospective analysis of data from 6 clinical trials using injectable anti-vascular endothelial growth factor (anti-VEGF) ranibizumab (Lucentis/Genentech) has shown that the relationship between some measurements may be more complex than believed.
Although relationships between best-corrected visual acuity (BSVA) and centralized retinal thickness (CRT) measured by spectral domain optical coherence tomography (SD-OCT) exist to some degree in age-related macular degeneration (AMD), diabetic macular edema (DME), and retinal vein occlusion (RVO), the relationships show a wide variance and may be complicated by other disease factors.
The data showed that CRT may not be the best indicator of disease progression or visual acuity in AMD or RVO. Led by William C. Ou, MD, FACS, with Retina Consultants of Houston, collected data investigating ranibizumab and dosing regimens for AMD, DME, and RVO. The 6 studies included a total of 387 eyes from 345 patients who received ranibizumab treatment in dosages ranging from 0.3 mg to 2.0 mg/ 0.05 mL and underwent BCVA testing and SD-OCCT testing scans at baseline and 12 months.
The study data suggests that AMD, RVO, and DME each have a different relationship to CRT when it comes to visual losses or gains. Although anti-VEGF treatments such as ranibizumab have been proven effective in treating all 3 diseases, there seems to be a more complex relationship, according to Ou, “between structure and visual function” necessitating more study into that relationship, including any comorbidities and/or confounding factors for each disease.
Individual analysis and analysis pooled by disease type, with a specific focus on “change in BCVA as the dependent variable and change in CRT from baseline, baseline BCVA, baseline CRT,” and other independent demographic variables such as age, gender, and comorbidity status (ex. diabetes or hypertension) were examined.
Ou and colleagues discovered that at baseline pooled data from AMD studies showed a “significant but small negative correlation” between BCVA and CRT (r= -0.24, P= .017). Pooled data on BCVA and CRT among DME patients showed “significant medium negative correlations (r = -.042, P < .001). Data from RVO trials showed no significant correlation or relationship between BCVA and CRT (r = -0.11, P = .635)….
Read more: http://www.mdmag.com/medical-news/crt-vision-loss-have-complex-relationship
Source: MD Mag

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