Enophthalmos is the posterior displacement of the eyeball within the orbit due to changes in the volume of the orbit (bone) relative to its contents (the eyeball and orbital fat), or loss of function of the orbitalis muscle.

It may be a congenital anomaly, or be acquired as a result of trauma (such as in a blowout fracture of the orbit), Horner's syndrome (apparent enophthalmos due to ptosis), Marfan Syndrome, silent sinus syndrome, or phthisis bulbi.

Late-onset enophthalmos after orbital decompression was associated with clinical and radiologic features that resemble the idiopathic imploding antrum syndrome. In all patients, the ethmoidal infundibulum was obstructed by prolapsed orbital fat with secondary antral consolidation, and inward bowing of the maxillary walls was present in five of six patients. After antral drainage and packing, there was an improvement in enophthalmos (mean, 2.7 mm range, 0-4 mm) and all but one globe returned to within 2 mm of exophthalmometry of the contralateral eye. For recurrent enophthalmos in two patients (minor in one patient and marked in the other), later repair of the orbital floor was undertaken through a lower eyelid swinging flap, using porous polythene sheet, with good cosmetic outcome.