Aim: A case of severe normal tension glaucoma is reported in a trumpet player, along with a study investigating the association between glaucoma and raised intrathoracic pressure, using measurements of pulsatile ocular blood flow (POBF). Methods: Three patient groups were studied; normals (n = 34), untreated primary open angle glaucoma (POAG) (n = 20), and untreated normal tension glaucoma (NTG) (n = 22), with a total of 76 patients who underwent measurements of POBF using the OBF pneumotonometer at rest and while forcibly exhaling through a mouthpiece connected to a mercury manometer (30 mm Hg) (Valsalva manoeuvre). Results: POBF fell during Valsalva in all groups with the greatest predictor being the resting value of POBF. There was no evidence of significant differences in the mean change in POBF occurring during the Valsalva manoeuvre for the three groups studied before or after adjusting for the sex, the resting POBF, and the resting IOP of the patients (p = 0.294 and p = 0.542, respectively). However, statistically significant associations were found between the change in POBF and sex (p = 0.049), resting POBF (p<0.0001) and resting IOP (p = 0.032). Males had a greater drop, on average, in POBF during Valsalva manoeuvre than females after adjusting for the other factors. Additionally, there was a significant difference in the mean change in IOP during Valsalva for the three groups (p = 0.002), with the difference occurring between the normal and POAG groups (p<0.005). The POAG group had, on average, a drop in IOP during Valsalva, while the other two groups had an increase in IOP. Also noted was a significant difference in the distributions of the risk factors among the three groups (p = 0.002). Conclusions: This study demonstrates no difference between groups with respect to resting or Valsalva POBF, but does demonstrate a possible trend with respect to IOP, with a drop in IOP occurring during Valsalva in the POAG group. There is, however, much variability in the data left unexplained by our models. Thus, unfortunately, we cannot advise our trumpet player whether his NTG is directly related to his trumpet playing.A 60 year old man presented with optic disc cupping, and visual field defects (right eye; vertical cup:disc ratio 0.4, mean defect −3.55 dB, left eye; vertical cup:disc ratio 0.7 with an inferior notch, mean defect −16.26 dB). Intraocular pressures were 17 mm Hg in each eye and mean resting pulsatile ocular blood flow (POBF) at rest was right eye 947 µl/min; left eye 812 µl/min. He reported that he was a professional trumpet player and inquired whether he could continue playing for 5 hours each day. While trumpet blowing the following single readings were obtained, right eye 515 µl/min; left eye 849 µl/min.The playing of high resistance wind instruments such as the trumpet involves expiration against resistance, mimicking the Valsalva manoeuvre. We designed this study to investigate the effect of the Valsalva manoeuvre upon POBF in normal patients, and untreated patients with primary open angle gl...