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Rodrigo Müller, Elise Taniguchi, Andrea Cruzat, Bernardo M Cavalcanti, Claes H Dohlman, Pedram Hamrah; Longitudinal Assessment of Boston Type 1 Keratoprosthesis/Cornea Interface by Anterior Segment-OCT Allows Detection and Monitoring of Corneal Tissue Melts. Invest. Ophthalmol. Vis. Sci. 2015;56(7 ):1123.
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© ARVO (1962-2015); The Authors (2016-present)
To prospectively evaluate the presence and alterations of potential spaces and areas of tissue melting(gaps) in the donor cornea, under the Boston Type 1 Keratoprosthesis (K-Pro1) front plate, as well as corneal epithelial tissue lipping over the edge of the front plate(epi-lip), using anterior segment-optical coherence tomography(AS-OCT).
AS-OCT (RTVue OCT, Optovue Inc., Fremont, CA) was performed at the device-donor corneal interface in all 4 quadrants(qds) around the K-Pro1 at two time points (mean follow-up time of 1.3±0.98years). Presence, alterations, and size of gaps between the front plate and the donor cornea, as well as epi-lips, were evaluated at baseline and follow-up.
Forty-two eyes of 36 patients were assessed(mean of 4.8±2.9years after surgery), and 25 eyes of 23 patients were analyzed at follow-up. From 154 OCT qds imaged at the first visit, 56(36.3%) revealed a gap under the front plate. The gap area was on average 12.7±33.3µm2. Among the qds with gaps, 19(34%) revealed no epi-lip, while among the qds without gaps, only 3(3.0%) had no epi-lip (p<0.0001). In addition, the epi-lip area was significantly smaller among the qds with gaps compared to qds without gaps(22.1±23.8 and 49.5±49.8µm2,p<0.0001). There was a significant correlation between the gap area and epi-lip area (r=-0.33,p<0.0001). On follow-up examination, 60% of the qds remained without gaps(from 20 eyes), 17% remained stable or regressed(from 12 eyes) and 23% progressed(from 12 eyes), with one eye advancing to extrusion and two eyes having had a prior history of extrusion in the previous K-Pro. Among those qds with gaps that progressed, 30% had no epi-lip during the first visit while, among those qds that remained stable or regressed, 18% had no epi-lip. Finally, among those qds that remained without gaps, only 3% had no epi-lip(p<0.0001). The relative risk for progression of gaps at the follow-up visits was 1.7(p=0.07); however, it was 3.2 in qds with no epi-lips during the first visit, compared to qds with epi-lip (p=0.0005).
Patients with K-Pro Type 1 may demonstrate gaps under the front plate. The epi-lip may confer protection against development of gaps. While corneas in patients without gaps remain stable, presentation of gaps can progress and could demonstrate a risk factors for corneal melting, requiring closer follow-up.
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