Ocular hemorrhages were also demonstrated in a porcine model in which animals were subjected to nonimpact high-speed rotation. These symptoms and signs are caused by the acceleration forces leading to congestion and elevated intravascular pressure. Previous reports of pilots subjected to 3–4 g negative g force include complaints of severe headache, a sensation that ‘the eyes are popping out of the head’, red vision, facial swelling, petechiae and diffuse, subconjunctival hemorrhages. Confusion and loss of consciousness occur at 4–5 g. Ocular discomfort occurs almost immediately, and subconjunctival hemorrhages occur at 2–3 g. Conversely, the body cannot be trained to tolerate negative g forces. The human body is much more tolerant to positive g forces, as a typical person can withstand 4–5 g, and pilots who undergo high- g training can withstand even 9 g. Since 1 g equals 9.81 m/s 2, the radial acceleration force to which our patient was subjected was 2.61 g.Īlong the vertical axis, positive g force drives blood from the head to the feet, and negative g force drives blood from the feet to the head. Īcceleration forces may be expressed as ‘ g’ forces, which are multiples of the constant acceleration exerted by the earth's gravity. (fig.1a) 1a) as well as petechiae in both ear canals and on the soft palate.Ī r = ( 20 k m h ) 2 1.2 m = ( 5.55 m s ) 2 1.2 m = 25.67 m / s 2. Additional findings of the physical examination included a mild swelling and periocular petechiae (fig. There was no limitation in ocular motility. Intraocular pressure was 12 mm Hg in both eyes, and pupillary responses were normal. The remainder of the examination was normal, with clear corneas and lenses, no intraocular hemorrhage of any kind and normal dilated fundus examination. Bilateral subconjunctival hemorrhages were noted in both eyes (fig. On examination, visual acuity was 20/20 OU. After dismounting the carousel, the boy complained of a headache, his face was swollen, both eyes were red and he was brought to the emergency room in our institution. The rapid spinning lasted for about 1 min, during which the boy suffered an intense headache, but did not lose consciousness. The boy had no control of the carousel, but fortunately an adult managed to disconnect the scooter. He had mounted a carousel that was attached to an electrical scooter, and had spun round on it very rapidly. A healthy, 10-year-old boy was examined in our institution due to bilateral diffuse subconjunctival hemorrhage.
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