Response to comments on: Keratoprosthesis optic and carrier corneal graft “noncontact” as a cause of sterile stromal necrosis in a case of Auro KPro implantation

Dear Sir,

We thank Harissi-Dagher et al.[1] for the interest shown in our case report “Keratoprosthesis optic and carrier corneal graft 'noncontact' as a cause of sterile stromal necrosis in a case of Auro KPro implantation.”[2] The authors' agree with their observation that keratolysis in cases implanted with the Boston K Pro I or its prototypes may have varied etiologies, the more common ones being retroprosthetic membrane (RPM) formation and infectious keratitis.[3] However, in our case, a retroprosthetic membrane was not noted on slit lamp examination and infectious keratitis was ruled out by taking corneal scrapings, which returned negative microbiological results for both bacteria and fungi.

Sterile carrier graft melt with edge lift of the keratoprosthesis and a perioptic annular melt with an entrapped air bubble beneath the flange of the optic has been documented photographically by Iyer et al.[4] in a recent review article. In our case, since an area of noncontact, i.e., edge lift of the keratoprosthesis optic was noted in the early postoperative period and was associated with frequent contact lens loss, the authors' felt that this was the most likely factor responsible for the corneal melting. While surgeons must be aware of the more common causes leading to keratolysis the purpose of this case report was to draw attention to an avoidable cause, i.e., inadequate apposition between the carrier graft and optic rim of the keratoprosthesis, which can be prevented by meticulous attention to the assembly of the keratoprosthesis carrier graft complex.

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