Abstract
Introduction::
Several studies on the vascularisation of hydroxyapatite orbital implants are available in the literature. Medpor (porous polyethylene) implants, which are increasingly popular, have been less well studied especially in human subjects.
Purpose::
To assess the degree of vascularisation in explanted medpor and hyroxyapatite orbital implants. To compare the vascularisation in explanted medpor implants following enucleation and evisceration.
Methods::
This is a retrospective case series of 7 explanted orbital implants - 1 hydroxyapatite and 6 medpor orbital implants. The implants were explanted between 11 months and 64 months post implantation. The implants were subjected to light microscopy and immunohistochemical studies after complete decalcification.
Results::
There were 2 post evisceration implants, 3 post enucleation implants and 2 secondary implants in the study. One hydroxyapatie implant in an enucleated eye and one medpor implant inserted as a secondary implant were wrapped in vicryl mesh. Two implants had an alloderm patch graft anteriorly. There were no diabetics in this series of patients. Histopathology revealed complete vascularisation up to the core of the implant in all the cases. Two cases showed evidence of chronic inflammatory infiltrate in the exposed part of the implant and one patient with infection had evidence of acute inflammation and gram positive cocci. Foreign body type giant cells and melanophages were also demonstrated on histopathologic examination. Eviscerated specimens showed scleral remodelling and thickening. The size of the implants varied from 18 to 22mm diameter. The reason for explantation was exposure in all 7 cases with additional infection in 2 cases.
Conclusions::
After a period of 11 months, all the implants readily vascularized up to the core of the implant. There is histologic evidence of chronic inflammation at the site of implant exposure. The sclera does not impede vascularisation of the implants in eviscerated specimens. Though the sample size is small, we found no difference in vascularisation of the explanted implants following enucleation and evisceration.
Keywords: vascular cells • inflammation • blood supply