Spearman correlations between clinical and quantitative MRI measures in patients with chronic progressive external ophthalmoplegia (A). A single mean value for each parameter was calculated in each patient for the common regions of interest (superior rectus, inferior rectus, medial rectus and lateral rectus). Range of eye movement (ROEM) correlated with T2 relaxation time. The cross-sectional area did not correlate with either ROEM or disease duration. Scatter plots are shown for T2 versus ROEM (B) and area versus ROEM (C)