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Cynthia X. Qian, Salima Hassanaly, Mona Harissi-Dagher; Long-term Follow-up Of Implanted Boston Type I Keratoprosthesis And Angle Structural Changes Using Anterior Segment Optical Coherence Tomography. Invest. Ophthalmol. Vis. Sci. 2012;53(14):6071.
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The need to better visualize the assembled Boston Keratoprosthesis (KPro) postoperatively is becoming increasingly pertinent, particularly in the detection of glaucoma, a frequent complication and the most common cause of progressive secondary visual loss despite surgical and optical success. We undertook this study to evaluate the role of anterior segment optical coherence tomography (OCT) as a standardized method of imaging the KPro postoperatively.
In this prospective interventional case series of 20 patients, follow-up was over a mean of 13.3 months (range 9 months-19 months). A thorough review of the patients’ ophthalmic, glaucoma, surgical and medication history was performed. After aphakic KPro implantation, the patients were imaged following an imaging protocol that allowed juxtaposition and comparison of the same imaging coordinates obtained pre-operatively and at 3 months, 6 months and 12 months post-operatively. The results were compared to the clinical progress.
14 patients improved clinically after surgery, two remained stable and four patients deteriorated. The average pre-op VA for patients was 1.91 ±0.47. Post-operatively, VA improved and achieved an average best VA around 3 months of 0.71 ±0.36 (p<0.0001) before settling at an intermediate level (P=0.0001). Of the patients who deteriorated, one progressed to terminal glaucoma and three experienced severe hypotony. No imaging characteristics predicting predispositions to these complications were identifiable upon review of serial OCTs. 14/20 patients were already known to have glaucoma pre-op. OCT imaging detected de novo anterior chamber narrowing and synechial changes in 10/20 patients. This compares to 5 diagnoses of glaucoma progression based on clinical investigation alone. Only two glaucoma progressions were corroborated using both clinical and imaging methods. Thus, in 8 patients, imaging data on angle changes preceded clinical glaucoma progression. Synechial and angle closure changes occurred most frequently in the 0-180 degree axis on OCT imaging.
Our study suggests that use of anterior segment OCT postoperatively is useful in complementing tools already implemented for glaucoma investigation, doubling the number of glaucoma progression cases picked up before clinically detectable deterioration. The pattern of synechiae location along the horizontal poles adjacent to the graft is striking. If correlated with the shape and position of KPro grafts within the host-graft interface, this may dictate a major impact on future changes in the design, sizing and fit of the Boston KPro.
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