Evaluation of the Stability of Boston Type I Keratoprosthesis–Donor Cornea Interface Using Anterior Segment Optical Coherence Tomography

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Purpose:To evaluate the anatomic stability of an implanted Boston type I keratoprosthesis (KPro)-donor cornea interface and assess the presence or absence of a potential space (gap) between the KPro front plate and donor cornea using anterior segment optical coherence tomography (AS-OCT). The presence of a gap would raise concerns of a possible pathway for the exchange of extraocular fluid with the anterior chamber.Methods:Fifteen eyes implanted with a Boston type I KPro were studied by the noncontact technique of AS-OCT (AC Cornea OCT prototype; OTI, Canada). All the KPro devices had been implanted at least 4 weeks before the study (mean: 7 months, range: 1-22 months). Eight eyes had aphakic Kpros, and the other 7 had pseudophakic implants. Anesthetized eyes were imaged before and during pressure application using sterile cotton-tip applicators. Pressure was applied for 10 seconds on the nasal or temporal side of the eye. Images were analyzed for any possible changes in the KPro-donor cornea interface during the application of pressure.Results:Of 15 eyes, 10 had the threaded front plate model with a T-shaped silhouette and corrugated sides, whereas 5 had the threadless type with a T-shaped silhouette and smooth sides on cross-sectional optical coherence tomography. Of the 15 eyes, 2 revealed a gap between the front plate and the surface of the donor cornea. The rest revealed no gaps. With pressure, none of the eyes, including the 2 with gaps, demonstrated any change in the KPro-donor cornea interface during dynamic imaging (eg, gaping or evidence of fluid escape along the KPro-donor cornea borders). In all eyes, the position of the titanium locking ring was visible and verified to be in an adequate position.Conclusions:The implanted KPro-donor cornea interface seems to be stable dynamically using AS-OCT. A gap that has been documented with this imaging tool showed neither gaping nor escape of anterior chamber fluid during dynamic cross-sectional imaging. Further studies will be needed to assess the cause of these gaps and to determine if they are possibly related to the hydration status of the cornea, suture tension on the donor cornea, or other factors that remain to be determined.

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