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Joelle Hallak, Rushi K Talati, Jose De la Cruz, Maria Soledad Cortina; Retroprosthetic Membrane Formation in Boston Keratoprothesis: A Case Control Matched Comparison of Titanium versus PMMA Back Plate.. Invest. Ophthalmol. Vis. Sci. 2016;57(12):2379.
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© ARVO (1962-2015); The Authors (2016-present)
Retroprosthetic membrane (RPM) formation is the most common complication following Boston keratoprosthesis (Kpro) implantation. While design changes have been made to improve tissue compatibility, little evidence exists comparing the frequency of RPM formation in various Kpro models. This retrospective, case-control matched study compared the frequency of RPM formation in patients implanted with a titanium back plate Kpro versus patients implanted with a polymethyl methacrylate (PMMA) back plate Kpro.
Twenty-one eyes from 21 consecutive patients implanted with a titanium back plate Kpro were case-matched with 21 eyes from 21 patients implanted with a PMMA backplate Kpro by a single surgeon at a large academic center. Case-matching was based on preoperative diagnosis, type of surgery (e.g. aphakic vs pseudophakic, Kpro only vs Kpro combined with vitrectomy and/or glaucoma shunt) and age. Formation of visually significant RPM requiring YAG laser treatment or surgical membranectomy was the primary outcome measure. Initial visual acuity (VA), best corrected visual acuity (BCVA), and VA at follow-up were secondary outcome measures. Paired and unpaired t-tests were performed for statistical significance.
Ten patients implanted with a titanium Kpro developed visually significant RPM compared to 7 patients implanted with a PMMA Kpro (p=0.38). Time from surgery to YAG treatment was not significantly different between the titanium and PMMA groups (227.10 ± 44.58 days vs 275.86 ± 75.50 days). Initial VA prior to surgical intervention was better for titanium Kpro patients (14.3% vs 0% had VA of 20/200 or better; p=0.03 for mean VA difference). Following surgery, patients implanted with a titanium Kpro achieved BCVA earlier (63.19 ± 16.44 days vs 173.90 ± 34.16 days; p=0.01), however the BCVA was not found to be statistically different (p=0.19). VA at most recent follow-up was not significantly different between the two groups (p=0.92).
Titanium Kpro back plates do not seem to significantly reduce RPM formation compared to PMMA Kpro back plates when patients are controlled for preoperative diagnosis. However, a larger prospective study would be necessary to confirm these findings. While differences in visual outcomes exist between the two Kpro models in the short-term, they are temporal and insignificant in the long-term.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.
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