Mechanisms and treatment of extruding intraconal implants: socket aging and tissue restitution (the "Cactus Syndrome")

Abstract

Objective: To investigate the initial features and treatment of 26 consecutive patients referred with extruding orbital implants between January 1991 and December 2004.

Methods: Retrospective medical record review recording the reason for enucleation, primary implant type, infection when initially seen, time to implant exposure, location of conjunctival defect, and time to surgical revision.

Results: Of the 26 eyes, 16 (62%) were removed after trauma, 3 (12%) because of tumor, 3 (12%) because of infection, and 4 (15%) because of painful blind eyes (percentages do not total 100 because of rounding). Of the 26 eyes, 8 (31%) were right eyes and 15 (58%) were hemispheric implants; 8 implants (31%) were acrylic or glass spheres, and 1 (4%) each was a hydroxyapatite, porous polythene, or bone sphere. Hemisphere extrusion occurred at a mean of 16 years after implantation, significantly later than with spheres (mean, 10 years after implantation; P = .05). The conjunctiva was breached medially in only 1 (sphere) (4%), centrally in 13 (50%), and laterally in 12 (46%). Lateral erosion occurred solely with hemispheres, in contrast to central erosions, in which 10 of 13 (77%) were spheres (P < .001). Twelve patients (46%) underwent surgical revision within a year of extrusion, 7 (27%) within 2 years, and the remaining 7 (27%) at 2 to 21 years.

Conclusions: Exposure of hemispheres occurred later, from pressure erosion at their prominent lateral edge. In contrast, central erosion (in spheres) occurred earlier, because of gradual tissue restitution after forced-ball implantation ("cactus syndrome"). This may be avoided by implantation through a polythene glide.