Purpose:
To assess anatomical characteristics of the implanted Boston keratoprosthesis (KPro) type I biointegration including front plate epithelialization and front plate-graft and stem-graft apposition using the high-definition spectral-domain anterior segment optical coherence tomography (AS-OCT).
Methods:
Sixteen consecutive eyes of 15 patients from the Weill Cornell Medical College Department of Ophthalmology with the KPro type I were included in this retrospective case series. Demographic and clinical data was recorded. All eyes were evaluated using Cirrus AS-OCT (Carl Zeiss Meditec, Inc, Dublin, CA). Patients underwent imaging in four quadrants (superior, inferior, nasal, temporal) using a 5-line high-resolution raster scan at the site of corneal graft-KPro interface and donor-host interface. Characteristics of KPro integration were determined and the apposition of the front plate and stem and the presence of epithelium over the front plate were assessed.
Results:
The mean duration between AS-OCT imaging and KPro placement was 24 months (range 1 to 64 months). The most common indication for KPro placement was previous failed grafts. The majority of the KPro devices implanted (94%) were aphakic. Eleven of 14 eyes (78%) underwent concomitant ocular surgeries. As assessed by the AS-OCT, 12.5% of the KPro devices had minimal to no epithelium growing over the front plate. One developed an infectious keratitis at the donor tissue adjacent to the front plate. Most of the KPro devices (56%) had good apposition with the front plate. When a gap between the corneal graft-KPro interface was present (44%), the mean distance was 71.6 microns. The apposition with the donor cornea and the front stem was also measured. The mean of the separation between the two structures was 68.8 microns. The graft-host interface was evaluated in one of patients with a wound leak which revealed a small step at the interface requiring a wound revision and additional sutures.
Conclusions:
The spectral-domain AS-OCT permits the high resolution imaging of KPro biointegration. The preliminary observations presented here, including front plate epithelialization, the gap between the front plate and the donor corneal as well as the lack of complete apposition of the cornea to the stem, may provide further insights into the stability of the implanted device and may help identify those at risk for KPro related complications such as extrusion and endophthalmitis.
Keywords: imaging/image analysis: clinical • keratoprostheses • imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound)