Predictors of Efficacy of Intravitreal Ranibizumab for Choroidal Neovascularisation Secondary to Age-Related Macular Degeneration: First Eye Affected vs Second Eye Affected

Abstract

Purpose: : To investigate potential predictive factors of efficacy of intravitreal ranibizumab treatment in patients with choroidal neovascularisation (CNVM) secondary to age-related macular degeneration, as measured by changes in visual acuity (VA) and central macular thickness (CMT). Specifically, to test the hypothesis that patients presenting with 2nd eye involvement have better response than those presenting with 1st eye involvement, due to presumed earlier presentation (little compensation by other eye; already engaged in service) and treatment.

Methods: : A retrospective study was conducted of patients treated with ranibizumab for CNVM and followed up for 24 weeks (n=50). Patients were divided into 2 groups: ‘1st eye affected’ were those with no previous history of CNVM (n=10); ‘2nd eye affected’ were patients with a history of CNVM in the fellow eye (n=40). VA was measured using the Early Treatment Diabetic Retinopathy Study (ETDRS) score and CMT using optical coherence tomography (OCT) at baseline and 24 weeks. Statistical methods used were independent samples T-test with correction for variance inequality and linear regression.

Results: : There was no significant difference between sex and age demographics of the groups. There was no significant difference between change in VA (ETDRS letters) (p=0.126) or change in CMT (p=0.360) between groups. Of interest, there was a significant difference in baseline VA (p=0.006), with 1st eye having lower baseline VA than 2nd eye. Given the (non-significant) trend for 1st eye group to have better VA change at 24 weeks, correlation between baseline VA and change in VA across all patients was tested and was significant (p=0.009).

Conclusions: : The study did not support the hypothesis of 1st or 2nd eye affected by CNVM as a predictive factor for either VA or CMT change 24 weeks post initiation of ranibizumab therapy. The study did show that 2nd eye patients had higher baseline acuity than those presenting with their first episode, so were indeed presenting earlier. However, it appeared that efficacy of treatment was significantly better for those with a lower VA at baseline. So the a-priori assumption that earlier treatment (as defined by better VA at baseline) meant better outcome was not supported by this study. Larger numbers for the 1st eye affected group and longer follow up however is needed to make more robust conclusions.

Keywords: age-related macular degeneration • choroid: neovascularization • vascular endothelial growth factor