Cross-sectional Relationships between Clinical Measures of Vision in an AMD Population

Abstract

Abstract: : Purpose: To examine the relationships between measures of vision which are normally used in clinical practice in a population with age-related macular degeneration (AMD). Methods: A database of 469 subjects with a diagnosis of AMD in one or both eyes was constructed. All subjects had logMAR distance (DVA) and logMAR near acuity (NVA) and log contrast sensitivity (CS) measured in both eyes to a standardised protocol. One eye of each subject was nominated the study eye and this was generally the presenting eye. Plots similar to Bland and Altman plots were used to explore relationships between the following pairs: DVA and NVA, DVA and CS, NVA and CS. Results: Bland and Altman plots showed that DVA and NVA were identical both when measures of vision were very good or very poor. Where DVA was 0.90 logMAR (mid range) there was maximum disparity with NVA which was 3.76 lines worse than DVA. When the pair consisting of NVA and CS was examined, maximum disparity again occurred at 0.89 (which is in the mid-range) with a difference of 3.3. When DVA and CS were examined a linear relationship was found. When data from fellow eyes was analysed, we obtained similar results. Conclusions: The pairs, DVA and NVA and NVA and CS, exhibited quadratic relationships over the vision scale resulting in least concordance in the mid range, suggesting that NVA decreases at a faster rate than either DVA or CS. Our data also suggest that CS and DVA fall at the same rate. These findings were supported by the similar relationships detected in the fellow eye .

Keywords: age-related macular degeneration • aging: visual performance • clinical (human) or epidemiologic studies: out