This is a retrospective review of the change over time in the sub-brow fat volume in 104 patients with thyroid eye disease. Standardised photographs taken at diagnosis were compared with those taken after an average period of 10 years (+/- 0.23 years). Photographs were graded by four trained observers using a previously validated technique. Each brow was given a score from zero to three by comparison with a set of four standard photographs with increasing amounts of soft tissue expansion of the brow, with three being the most severe. If there was asymmetry the worse affected brow was graded. Patients who had previously undergone brow surgery were excluded. In 56 patients the grade improved over time, and in 32 it worsened, but overall there was a significant improvement from an average grade of 1.24 to 1.00 (p<0.001). A higher initial grade was associated with improvement. None of the other variables including surgery, disease activity, medical treatment, age, sex or follow-up time was significantly associated with improvement. The study is interesting and is the first to document a degree of spontaneous reduction in sub-brow fat deposition over time in thyroid eye disease patients. The major weakness is the lack of comparison with age-matched controls, and the authors acknowledge previous studies showing age-related loss of facial soft tissue volume. This natural ageing may explain some of the observed changes, but probably not all the effect, nor the greater improvement in those with worse initial disease.