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C. H. Dohlman, K. A. Colby, M. W. Belin, A. Todani; Titanium vs. PMMA Backplates for Boston Keratoprosthesis: Incidence of Retroprosthetic Membrane. Invest. Ophthalmol. Vis. Sci. 2009;50(13):1505.
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© ARVO (1962-2015); The Authors (2016-present)
The formation of a retroprosthetic membrane (RPM) is an indication of postoperative intraocular inflammation. The purpose of this retroactive study has been to compare a keratoprosthesis (KPro) backplate made of titanium with the standard PMMA back plate. Any difference in RPM formation would result from different degrees of inflammation.
The design was a retroactive analysis looking at the surgical outcomes after 6 months in patients who had Boston KPro implants by 3 surgeons (CHD, MWB, KAC). Pediatric cases were excluded. The indications for having a KPro implant were broadly divided into three categories: autoimmune (n=12), chemical burns (n=5) and others (non-autoimmune) (n=47). Three types of back plates were studied: 1) threaded (screw-on) PMMA (n=30) 2) non-threaded (snap-on) PMMA (n=13) and 3) non-threaded titanium back plate (n=21). Main outcome measured was incidence of RPM formation at 6 months after surgery that warranted removal by either YAG laser membranotomy or surgery.
The percentage of patients who developed RPM was greatest in the threaded PMMA group (50%), followed by the non-threaded PMMA (38%), although this difference did not achieve statistical significance (p=0.5). The non-threaded titanium group showed the least RPM formation (10%), which was significantly less than both the threaded PMMA (p=0.002) and the theadless PMMA (p=0.043) groups.
Titanium KPro backplates induce less RPM than PMMA backplates, threaded or non-threaded. It seems that the titanium plates in this setting are more tissue friendly and cause less inflammation than PMMA.
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