Post-enucleation socket syndrome—a novel pathophysiological definition

BACKGROUND: The last definition of the post-enucleation socket syndrome (PESS) by Tyers and Collin—formulated almost 40 years ago in 1982—is predominantly based on the clinical characteristics and does not include the insights of newer studies into the pathophysiological mechanism of the PESS. METHODS: A systematic PubMed literature review regarding the pathophysiological mechanism of the PESS was performed, and results were comprised to give an overview of the current knowledge of the PESS including the exact pathophysiological mechanism. RESULTS: The primarily postulated pathophysiological mechanism of the PESS was the atrophy of orbital tissues, especially of fat, resulting in variable clinical findings. Newer studies using high-resolution computed tomography and magnetic resonance imaging or performing histopathological analyses found no orbital fat atrophy but rather a rotatory displacement of the orbital tissues from superior to posterior and from posterior to inferior together with the retraction of the extraocular muscles and a possible volume loss of the orbital implant by resorption if it is manufactured from hydroxyapatite. PESS results in a backward tilt of the superior fornix, a deep superior sulcus, a pseudo-ptosis, a lower eyelid elongation and laxity, a shallower inferior fornix, as well as enophthalmos and may lead to an inability of wearing ocular prostheses. CONCLUSIONS: A novel and comprehensive definition of the PESS is proposed: PESS is a multifactorial and variable syndrome caused by a rotatory displacement of orbital contents together with the retraction of the extraocular muscles and possible resorption of the orbital implant if it is manufactured from hydroxyapatite.