IN previous communications (Oksala and Lehtinen, 1959; Oksala 1960a, b), I noted that vitreous haemorrhages reflected echoes on the screen of an ultrasound equipment, and that these echoes were clearer if a fresh haemorrhage was involved. I also found that old haemorrhages, on account of the destruction of the vitreous, do not always become visible in ultrasonic examinations (Oksala and Lehtine...