Influence of dacron tissue thickness on the performance of the Pintucci biointegrable keratoprosthesis: an in vitro and in vivo study.

PURPOSE: In 1979 Pintucci developed a biointegrable keratoprosthesis with polymethylmethacrylate optical cylinder integrated with a Dacron tissue-colonizable supporting element to avoid the complications caused by the interaction between the haptic element and the eye. The purpose of this article is to compare the colonization of three Dacron fabrics (thicknesses of 0.25 mm, 0.6 mm, and 1.4 mm) in vitro and in vivo to optimize the device performance. METHODS: In vitro three different Dacron fabrics were cultured for 3 days with 3.5 x 10(5) human fetal lung fibroblasts and observed with a scanning electron microscope. In vivo three different Dacron fabrics were implanted on the sclera near the superior rectus insertion in the right eye of six albino rabbits and were observed after 4 days with light and scanning electron microscopy. RESULTS: In the in vitro experiments, the cells were preserved and their structure was found to be normal. The 0.25-mm thick fabric was coated only on the surface, and the other fabrics were colonized in three dimensions. In the in vivo experiments, the 0.25-mm thick fabric appeared coated only on its surface. The other fabrics were three-dimensionally colonized and the Dacron filaments appeared embedded in neovascularized connective tissue with minimal foreign body reaction. The 1.4-mm thick colonized fabric showed a substantial loss of pliability. CONCLUSION: Given that the 0.25-mm thick fabric was coated only by connective tissue, that the 0.6-mm and 1.4-mm thick fabrics were perfectly colonized, and that the 1.4-mm thick fabrics showed a substantial loss of pliability, the 0.6-mm thick fabric haptic part of the Pintucci keratoprosthesis is preferred. For 19 years, the 0.6-mm Dacron fabric Pintucci keratoprosthesis was implanted in 159 eyes with good results, overcoming the apparently inseparable difficulties represented by mechanical anchorage and biointegrability of a keratoprosthesis.

The Dacron felt colonizable keratoprosthesis: after 15 years.

Keratoprostheses (KP) are made of an optical cylinder integrated with a supporting element which governs their biocompatibility. The Pintucci KP with a Dacron tissue three-dimensionally colonizable support was designed in 1979 and has since been improved in order to reduce the complications associated with the use of KP. The biological background (in vivo and in vitro), electron microscopy observations and the surgical technique will be discussed. Sixty-three patients were operated from 1979 with different surgical techniques and Dacron tissues. Twenty transoral mucous KP were implanted with our most recent technique in severely vascularized corneas from 1985 to 1991, with a follow-up ranging from 48 to 85 months. The favorable results may be indicative of their better reliability.

New Dacron tissue colonisable keratoprosthesis: clinical experience.

BACKGROUND: Keratoprostheses (KPs) are made of an optical cylinder integrated with a supporting element which conditions their biocompatibility. A new KP with a Dacron tissue colonisable support has been designed in order to reduce significantly the complication rate. METHODS: This new KP was implanted into 20 eyes of 20 patients with bilateral corneal blindness unsuited to a corneal implant. The follow up ranged from 24 to 96 months. RESULTS: All 20 patients had some improved visual acuity with 13 retaining this improvement for more than 2 years. CONCLUSION: These favourable results may be indicative of the reliability of the new KP.

Evaluation of an experimental periodontal ligament for dental implants.

To improve the devices used in dental implantology, a new experimental supporting element has been developed. The device, made of titanium, poly(methylmethacrylate) and Dacron tissue, has been tested for the osteointegrability of its outer Dacron coat by implants in mandibular bone of rabbits. The Dacron filamentous tissue became incorporated by the bone at 3 month post-implantation. This might provide a reliable mechanical anchorage of the device and a barrier against epithelial proliferation and microbial contamination. Preliminary results relating to in vitro evaluation of the poly(methyl methacrylate)-Dacron fixation strength predict favourable mechanical behaviour at this interface and in the complete implanted device.

Exceptional case of bone resorption in an osteo-odonto-keratoprosthesis. A scanning electron microscopy and X-ray microanalysis study.

This article reports the findings of investigations on an osteo-odonto-keratoprosthesis in an eye that was enucleated owing to severe complications 12 years after implantation. Scanning electron microscopy and electron probe X-ray microanalysis showed extensive resorption of the bone that was used as a supporting element in the kind of transcorneal prosthesis developed by Strampelli. The destructive process, in addition to surgical trauma, has been associated with the early and recurrent bacterial infections relating to the presence of Staphylococcus epidermidis. The need to control the occurrence of primary bacterial infections in traumatized tissues during operations as well as further infectious situations, given the enhanced antibiotic-resistence of bacteria, is emphasized.

Steroids and neuroendocrine hormones detected by the immunoperoxidase technique from malignant melanomas and nevi of the choroid and conjunctiva.

By the peroxidase-antiperoxidase technique, the authors studied 7 malignant choroidal melanomas, 7 conjunctival nevi and 1 malignant conjunctival melanoma with the aim to detect the presence of vasoactive intestinal polypeptide (VIP), adrenocorticotropic hormone (ACTH), gastrin, estradiol and testosterone. Positive staining reaction for VIP, estradiol and testosterone was observed in both malignant melanomas of the choroid and conjunctival nevi. The case of conjunctival melanoma was positive for VIP and ACTH but not for estradiol and gastrin.