Origin of orbital blood cysts.

The origin of blood cysts as presented in the ophthalmic literature may be summarized as follows: (i) Blood cysts without epithelial or endothelial lining most probably result from the I937; Svoboda, I948). The orbital haematoma may result from trauma, blood disease, or strain that increases the pressure in the jugular veins. As there are no valves in these veins, this unobstructed pressure is transmitted to the vessels of the skull and may cause an orbital haemorrhage (Reese, I963). (2) Some probably occur as sequelae of previously unrecognized orbital lymphangiomata (Jones, 1957). (3) Others may occur as the result of traumatic fat necrosis which leads to the development of a cavity into which there may or may not be haemorrhage (Duke-Elder, I952). The following two cases are of extreme interest because they show clearly the origin of most orbital blood cysts. Case reports In these two cases there was no history of trauma nor did a complete medical examination reveal any abnormality. Casoni's test for hydatid cyst and the tuberculin test were negative. The basal metabolic rate and 131iodine uptake tests were normal. Postero-anterior skull x rays with 200 tube tilt showed no increased soft tissue density or tumour calcification in the orbit. There was orbital dilatation and a wider superior orbital fissure on the affected side; otherwise there was no abnormality in the orbital or peri-orbital region. Case i, a io-year-old boy, had right proptosis of 20 mm. (left side i6 mm.) of unexplained origin of 2 months' duration (Fig. I). Both eyes and fundi were normal with visual acuity 6/6. While he was in the hospital for investigation before orbital exploration, another child struck him in play with the fist on the right eye, and the proptosis immediately disappeared, but was followed by upper and lower lid ecchymosis (Fig. 2). A ruptured orbital blood cyst was diagnosed and the blood staining of the lids disappeared in one month. Progress One year later the boy presented again with severe right proptosis of 30 mm. of 6 days' duration (Fig. 3). There was oedema of the lids, conjunctival chemosis, and limitation of ocular movements