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EJ Dudenhoefer, JC Abad, A Tisdale, K Baratz, M Nouri, IK Gipson, T Dryja, CH Dohlman; Histopathology of Explanted Collar Button Keratoprostheses--A Clinico Pathologic Correlation . Invest. Ophthalmol. Vis. Sci. 2002;43(13):4167.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: To compare the histopathology of three PMMA collar button type keratoprosthesis (KPro)/corneal specimens, explanted due to various complications, with that from one Kpro/corneal specimen taken post-mortem from an otherwise "healthy" enucleated eye. Methods: Patient #1 (chemical injury) had no problems for 2 years after KPro placement; the entire eye was obtained post mortem. Patient #2 (repeated graft failures non-cicatrizing disease) developed an "un-laserable" retroprosthesis membrane 4 months after KPro placement. A new KPro/corneal implant was placed. Patient #3 (ocular cicatricial pemphigoid (OCP) related corneal blindness) developed corneal tissue melt at the KPro-cornea interface 7 months after KPro placement, and progressed to aqueous leak, despite repair procedures. The KPro/cornea complex was replaced. Patient #4 (OCP), developed progressive corneal melt around the KPro 3.5 years after placement. Repairs failed to stop leaking, resulting in replacement. All KPro/cornea specimens were placed in ½ strength Karnovsky’s fixative, dehydrated and soaked in acetone for 1 to 2 months to soften the KPro, and embedded in methacrylate. Sections were stained with hematoxylin and eosin. Results: In patient #1 (post mortem specimen), conjunctival epithelium extended beneath the KPro front plate to the stem without epithelial downgrowth. Inflammatory cells were noted in the epithelium, but not the stroma. Keratocyte density appeared normal. By comparison, patient #2 maintained a corneal epithelium, also without downgrowth. The stroma exhibited mild vascularity, moderate inflammation and normal appearing keratocyte density. A dense fibrous tissue membrane with inflammatory cells was present behind the KPro. Patients #3 and #4 exhibited dense fibrovascular pannus across the corneal surface with extensive keratocyte loss, fibrovascular scar formation, massive inflammatory cell infiltration, tissue necrosis with "melt" adjacent to the stem resulting in epithelial downgrowth Conclusion: Corneal inflammation and degradation after KPro placement correlate well with the pre-operative diagnostic category. Patients with cicatrizing, immune related corneal surface disease can exhibit strong inflammatory responses leading to necrosis, melt and epithelial fistula formation. Repair procedures may have little effect on this process. In contrast non-cicatrizing graft failure patients demonstrate a quieter histopathologic picture commensurate with their clinical appearance.
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