Keratoprosthesis surgery.

PURPOSE: To survey current knowledge of use of keratoprostheses for visual rehabilitation in the dry eye. METHODS: Sections deal with: (1) when a keratoprosthesis is indicated; (2) classification of keratoprostheses; (3) the osteo-odonto-keratoprosthesis (OOKP), its history, indications and contraindications, patient assessment, surgical technique, results and complications, and (4) the AlphaCor, its design, indications, results and complications. RESULTS: The choice of keratoprosthesis in the severely dry eye is straightforward, as only one device - the OOKP - will work. With careful assessment, adequate technique, regular follow-up, and early recognition and management of complications, most patients can look forward to many years of sight with an OOKP. In the appropriately managed marginally dry eye, an AlphaCor keratoprosthesis may be considered, although the device should be seen as an alternative to high-risk keratoplasty in multiple graft rejection and vascularised corneae. CONCLUSIONS: KPro surgery is a complex and growing field. Those interested are invited to join the KPro Study Group (www.kpro.org), to add their contribution to the ongoing research and device evaluation.

The osteo-odonto-keratoprosthesis (OOKP).

The osteo-odonto-keratoprosthesis (OOKP), although described over 40 years ago, remains the keratoprosthesis of choice for end-stage corneal blindness not amenable to penetrating keratoplasty. It is particularly resilient to a hostile environment such as the dry keratinized eye resulting from severe Stevens-Johnson syndrome, ocular cicatricial pemphigoid, trachoma, and chemical injury. Its rigid optical cylinder gives excellent image resolution and quality. The desirable properties of the theoretical ideal keratoprosthesis is described. The indications, contraindications, and patient assessment (eye, tooth, buccal mucosa, psychology) for OOKP surgery are described. The surgical and anaesthetic techniques are described. Follow-up is life-long in order to detect and treat complications, which include oral, oculoplastic, glaucoma, vitreo-retinal complications and extrusion of the device. Resorption of the osteo-odonto-lamina is responsible for extrusion, and this is more pronounced in tooth allografts. Regular imaging with spiral-CT or electron beam tomography can help detect bone and dentine loss. The optical cylinder design is discussed. Preliminary work towards the development of a synthetic OOKP analogue is described. Finally, we describe how to set up an OOKP national referral center.

Mitomycin-C for mucous membrane overgrowth in OOKP eyes.

PURPOSE: The aim of this study was to report the use of mitomycin-C (MMC) in the treatment of mucous membrane overgrowth in eyes with osteo-odonto-keratoprosthesis (OOKP). METHODS: Records of 4 cases with mucous membrane overgrowth after stage 2 OOKP surgery were reviewed. RESULTS: All the patients had undergone a mucous membrane trimming procedure followed by MMC application. None of the patients had any episode of recurrence of the mucous membrane overgrowth after a single application of MMC in the follow-up period that ranged from 1 to 11 years. CONCLUSIONS: MMC can successfully arrest mucous membrane overgrowth in OOKP-implanted eyes including refractory cases.

Serial 3-dimensional computed tomography and a novel method of volumetric analysis for the evaluation of the osteo-odonto-keratoprosthesis.

PURPOSE: To assess the use of serial computed tomography (CT) in the detection of osteo-odonto-lamina resorption in osteo-odonto-keratoprosthesis (OOKP) and to investigate the use of new volumetric software, Advanced Lung Analysis software (3D-ALA; GE Healthcare), for detecting changes in OOKP laminar volume. METHODS: A retrospective assessment of the radiological databases and hospital records was performed for 22 OOKP patients treated at the National OOKP referral center in Brighton, United Kingdom. Three-dimensional surface reconstructions of the OOKP laminae were performed using stored CT data. For the 2-dimensional linear analysis, the linear dimensions of the reconstructed laminae were measured, compared with original measurements taken at the time of surgery, and then assigned a CT grade based on a predetermined resorption grading scale. The volumetric analysis involved calculating the laminar volumes using 3D-ALA. The effectiveness of 2-dimensional linear analysis, volumetric analysis, and clinical examination in detecting laminar resorption was compared. RESULTS: The mean change in laminar volume between the first and second scans was -6.67% (range, +10.13% to -24.86%). CT grades assigned to patients based on laminar dimension measurements remained the same, despite significant changes in laminar volumes. Clinical examination failed to identify 60% of patients who were found to have resorption on volumetric analysis. CONCLUSIONS: Currently, the detection of laminar resorption relies on clinical examination and the measurement of laminar dimensions on the 2- and 3-dimensional radiological images. Laminar volume measurement is a useful new addition to the armamentarium. It provides an objective tool that allows for a precise and reproducible assessment of laminar resorption.

Unusual variant of chorda tympani syndrome, its management, and a proposal on the nervous pathways involved.

Chorda tympani syndrome is an uncommon condition with similarities to Frey syndrome. We describe a variant of chorda tympani syndrome and its management, and put forward a hypothesis for the nervous pathways involved; something that seems to be lacking in published material.