In Reply Mossböck and colleagues pose interesting questions regarding our study. We respectfully disagree with their claims, as outlined herein.
Mossböck and colleagues criticize the method used in our study to evaluate NEI VFQ-25 results, suggesting that we should have used the composite score. The composite score is calculated as the average of the 11 vision-target subscale scores provided by the questionnaire. This averaging is based on the assumption that these subscales measure the same underlying unidimensional construct. If such assumption is violated, it is not appropriate to report a single overall composite score. In fact, the unidimensionality of the NEI VFQ-25 has been questioned,1- 3 and it is for this exact reason that we refrained from using a simple averaged composite score in our analysis. We therefore find the comment that “attributing equivalence to the different subscales is crude” to be supportive rather than counter to our argument, as attributing equivalence to the different subscales is exactly what the composite score does. Regardless of this, we revisited our data and regressed the logarithmic transformation of the composite score on the rates of BVF loss and found a significant relationship (P = .004).
Lisboa R, Medeiros FA. Association Between Rate of Binocular Visual Field Change and Vision-Related Quality of Life—Reply. JAMA Ophthalmol. 2014;132(6):785-786. doi:10.1001/jamaophthalmol.2014.2005