Abstract
Purpose: :
Observational study to evaluate and describe the exisiting environment of the surfaces of polymethylmethacrylate (PMMA) keratoprostheses (KPro) after explantation due to bacterial infection, corneal melting or epithelial downgrowth by scanning electron microscopy (SEM)
Methods: :
Five PMMA keratoprostheses were analyzed by Scanning Electron Microscopy after being explanted for different reasons. Two were explanted due to streptococcal endophthalmitis, 1 a Boston KPro Type I and the other a Type II. The other three keratoprosthesis were explanted as they extruded due to corneal melting. One of the three also presented with presumed epithelial downgrowth. Acitve search for colonization of microbial elements, biofilm formation, and any evidence of epithelial of fibrous downgrowth was perfomed. Also, evaluation of the different surface adherences of the biofilm to the PMMA Keratoprostheses was done and compared among the two groups.
Results: :
SEM images showed significant adherence and biofilm formation in both infected PMMA KPros. In particular the rough grinded surfaces of the backplate as well as the titanium locking ring were particularly populated in contrast to the smooth polished surfaces of the inner optic front plate that were not as populated by biofilm formation. The three KPros from melted corneas showed smaller populations of biofilm. This group had similar adherent patterns as the infected ones, in the rough, non polished surfaces of the PMMA and the titanium compoments. In the coneal melted cases there was no evidence of epithelial downgrowth, but they did show a significant amount of inflammatory elements at the PMMA surface.
Conclusions: :
SEM images of explanted KPros presented in this study show clear evidence of biofilm formation with particular adherence to rough non polished surfaces of the PMMA and titanium components. Cases of corneal melting did not show clear evidence of downgrwoth by SEM. Differences in surface adherence and colonization of this potentially damaging biofilm suggest that possible polishing or alternate treaments to PMMA KPro surfaces might decrease or minimize adherence of these organisms.
Keywords: keratoprostheses • cornea: clinical science • transplantation