The bony orbit is (a) a goblet-shaped cone, open in front, within which, posterior to the eyeball, there is (b) a closed fasciomuscular space,1 for which I would suggest the term "protective retrobulbar space ;" the surgical importance of this space has not been appreciated. Overfilling of this space, even from slight circulatory alterations, which in other parts of the body gives rise to flushing and congestion, as in hyperthyroidism, here causes exophthalmos.
In suppurative and traumatic disturbances resulting from neighborhood lesions, the retrobulbar space is the most fundamental, although the least evident, element in the production of exophthalmos, for any factor outside the periorbita requires (a) a marked constriction of the capacity of the bony goblet-shaped bone to produce proptosis, but (b) slight overfilling of the protective retrobulbar space, whether it comes from the cranial cavity or from the orbital or nasal walls, will occasion exophthalmos.
EAGLETON WP. EXOPHTHALMOS FROM SURGICAL DISEASES, ESPECIALLY AS TO INVOLVEMENT OF THE PROTECTIVE RETROBULBAR SPACE. Arch Ophthalmol. 1935;14(1):1–40. doi:10.1001/archopht.1935.00840070011001
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