Osteo-odonto-keratoprosthesis surgery: a combined ocular–oral procedure for ocular blindness

Keratoprosthesis in dry eye disease

Bilateral corneal blindness with severe dry eye disease (DED), total limbal stem cell deficiency with underlying corneal stromal scarring and vascularization, combined with adnexal complications secondary to chronic cicatrizing conjunctivitis is a highly complex situation to treat. In such eyes, procedures such as penetrating keratoplasty alone or combined with limbal stem cell transplantation are doomed to fail. In these eyes, keratoprosthesis (Kpro) or an artificial cornea is the most viable option, eliminating corneal blindness even in eyes with autoimmune disorders such as Stevens-Johnson syndrome, ocular mucous membrane pemphigoid, Sjogren's syndrome, and nonautoimmune disorders such as chemical/thermal ocular burns, all of which are complex pathologies. Performing a Kpro in these eyes also eliminates the need for systemic immunosuppression and may provide relatively early visual recovery. In such eyes, the donor cornea around the central cylinder of the Kpro needs to be covered with a second layer of protection to avoid desiccation and progressive stromal melt of the underlying cornea, which is a common complication in eyes with severe DED. In this review, we will focus on Kpro designs that have been developed to survive in eyes with the hostile environment of severe DED. Their outcomes in such eyes will be discussed.

Contribution to oral and maxillary surgery and surgical technique of osteo-odontokeratoprosthesis in Japan

Osteo-odontokeratoprosthesis (OOKP) is a technique invented by Strampelli in 1963, in which the patient's own tooth root is used to support an optical cylinder. It uses an autologous tooth-bone-periodontal complex to mount an optical cylinder, which is stabilised by overlying autologous buccal mucosa. OOKP involves two, staged procedures done by ophthalmologists and oral surgeons, and the main contribution from the oral surgeon is during the first stage. To date we have done nine first-stage, and completed eight second-stage, OOKP operations in Japan with a mean follow-up of eight years and 11 months by modifying the original method of the oral surgery. All OOKP procedures were unilateral, and canines were selected as the donor teeth. Patients developed ocular blindness as a result of Stevens-Johnson syndrome, ocular cicatricial pemphigoid, and chemical and thermal burns to the cornea and ocular surface. All eight patients who completed the second stage have been stable, and there have been no major perioperative or postoperative oral complications. The patients' visual acuities were stable with no serious complications. Here we report the technical details of the oral contribution to OOKP.

Canine and Premolar Root Dimensions in Chinese. A Reference for Osteoodontokeratoprosthesis Surgery

PURPOSE

Osteoodontokeratoprosthesis (OOKP) surgery is used to restore vision in end-stage corneal disorders, where an autogenous tooth supporting an optical cylinder is implanted through the cornea under a buccal mucosal graft. The ideal tooth for OOKP is a healthy single-rooted permanent tooth with sufficient buccolingual/palatal root diameter to accommodate an optical cylinder. The aim of this study was to determine the buccolingual/palatal diameters of canine and premolar roots in Chinese, for selection of teeth for OOKP surgery.

DESIGN

This was an anatomical study on root dimensions of extracted intact teeth.

METHODS

Extracted canine and premolar teeth (excluding maxillary first premolars) were collected and the buccolingual/palatal and mesiodistal diameters of the root at the cervical line and at 2-mm intervals below the cervical line were measured with Vernier calipers. Other measurements included total tooth length, crown buccolingual/palatal diameter, and root length. Mean and minimum buccolingual/palatal root diameters were compiled for each 2-mm interval.

RESULTS

A total of 415 extracted teeth (198 male, 217 female) were collected and measured. Recorded dimensions of keratoprostheses in 55 previous OOKP surgeries were used to establish acceptable lamina dimensions to ascertain root size adequacy. Premolars in Chinese female patients were undersized in a small minority. Minimal dimensions of teeth were insufficient if at 6 mm root level, the buccolingual/palatal width was less than 5 mm, or the mesiodistal width was less than 3 mm. This was noted in female mandibular first premolars (5.6%), maxillary second premolars (4.5%), and mandibular second premolars (1.5%).

CONCLUSIONS

Canines have adequate dimensions for OOKP surgery. However, premolars in Chinese females may be undersized in a small minority.

Piezoelectric harvest of osteo-odonto-lamina in modified osteo-odonto keratoprosthesis: A maxillofacial perspective

Purpose:

We describe the piezo-osteotomy feasibility in rehabilitation and harvesting of osteo-odonto lamina in modified osteo-odonto keratoprosthesis (MOOKP) surgery. Surgery was evaluated regarding operative technique and success of the keratoprosthesis (KPros) in terms of perception to light (+ve) to finger counting (+ve).

Materials and Methods:

This retrospective cohort study included 12 patients undergone MOOKP surgery procedures. Harvesting of osteo-odonto-lamina was performed using piezosurgical osteotomy during 2007–2012.

Results:

The mean follow up was 34 months (range 24–48 months). Of the 12 patients six patients had vision ≥6/12, four patients had vision <6/12, but >6/60 and one patients had vision ≤6/60. KPros was retained and functional in all the eyes after a minimum follow up of 24 months. There was mucosal overgrowth over the optical cylinder occurred in two cases over 4 years follow up which was corrected with trimming. Postoperative complication at donor site was seen in three cases, two cases with exposure of root of adjacent teeth and oro antral fistula in one.

Conclusions:

This study suggests that piezoelectric harvest of osteo-odonto-lamina is a valuable surgical option in patients undergoing MOOKP surgery, resulting in high success rate with less complication.

Biocompatibility of a fish scale-derived artificial cornea: Cytotoxicity, cellular adhesion and phenotype, and in vivo immunogenicity

PURPOSE

To determine whether a fish scale-derived collagen matrix (FSCM) meets the basic criteria to serve as an artificial cornea, as determined with in vitro and in vivo tests.

METHODS

Primary corneal epithelial and stromal cells were obtained from human donor corneas and used to examine the (in)direct cytotoxicity effects of the scaffold. Cytotoxicity was assessed by an MTT assay, while cellular proliferation, corneal cell phenotype and adhesion markers were assessed using an EdU-assay and immunofluorescence. For in vivo-testing, FSCMs were implanted subcutaneously in rats. Ologen(®) Collagen Matrices were used as controls. A second implant was implanted as an immunological challenge. The FSCM was implanted in a corneal pocket of seven New Zealand White rabbits, and compared to sham surgery.

RESULTS

The FSCM was used as a scaffold to grow corneal epithelial and stromal cells, and displayed no cytotoxicity to these cells. Corneal epithelial cells displayed their normal phenotypical markers (CK3/12 and E-cadherin), as well as cell-matrix adhesion molecules: integrin-α6 and β4, laminin 332, and hemi-desmosomes. Corneal stromal cells similarly expressed adhesion molecules (integrin-α6 and β1). A subcutaneous implant of the FSCM in rats did not induce inflammation or sensitization; the response was comparable to the response against the Ologen(®) Collagen Matrix. Implantation of the FSCM in a corneal stromal pocket in rabbits led to a transparent cornea, healthy epithelium, and, on histology, hardly any infiltrating immune cells.

CONCLUSION

The FSCM allows excellent cell growth, is not immunogenic and is well-tolerated in the cornea, and thus meets the basic criteria to serve as a scaffold to reconstitute the cornea.

Indications for orbital decompression for patients undergoing keratoprosthesis surgery

INTRODUCTION

Optimizing the ocular surface and achieving acceptable cosmesis are important considerations in the rehabilitation of patients with keratoprosthesis (KPro). In osteo-odonto-KPro and type 1 Boston KPro surgery, it is important to ensure a healthy ocular surface to increase the chance of functional success.

MATERIALS AND METHODS

The authors present 2 patients with KPros undergoing orbital decompression surgery. This series highlights a novel indication for orbital decompression surgery for patients, who are usually 1-eyed, undergoing KPro surgery. It illustrates the importance of globe position to either optimize the ocular surface or allow a cosmetic shell to be worn. To the authors' knowledge, such indications for orbital decompression have not been reported to date.

RESULTS

Two-wall and intraconal fat orbital decompression surgery achieved globe retroplacement of 6 mm and 7 mm, allowing fitting of a cosmetic shell over the osteo-odonto-KPro and reducing lagophthalmos and corneal exposure in patients 1 and 2, respectively.

CONCLUSION

Indications for orbital decompression exist in patients undergoing osteo-odonto-KPro or KPro to reduce pseudoproptosis or exposure.

In vitro effect of a corrosive hostile ocular surface on candidate biomaterials for keratoprosthesis skirt

Aim

Keratoprosthesis (KPro) devices are prone to long-term corrosion and microbiological assault. The authors aimed to compare the inflammatory response and material dissolution properties of two candidate KPro skirt materials, hydroxyapatite (HA) and titania (TiO₂) in a simulated in vitro cornea inflammation environment.

Methods

Lipopolysaccharide-stimulated cytokine secretions were evaluated with human corneal fibroblasts on both HA and TiO₂. Material specimens were subjected to electrochemical and long-term incubation test with artificial tear fluid (ATF) of various acidities. Topography and surface roughness of material discs were analysed by scanning electron microscopy and atomic force microscopy.

Results

There were less cytokines secreted from human corneal fibroblasts seeded on TiO₂ substrates as compared with HA. TiO₂ was more resistant to the corrosion effect caused by acidic ATF in contrast to HA. Moreover, the elemental composition of TiO₂ was more stable than HA after long-term incubation with ATF.

Conclusions

TiO₂ is more resistant to inflammatory degradation and has a higher corrosion resistance as compared with HA, and in this regard may be a suitable material to replace HA as an osteo-odonto-keratoprosthesis skirt. This would reduce resorption rates for KPro surgery.

In vivo evaluation of titanium oxide and hydroxyapatite as an artificial cornea skirt

Keratoprosthetic devices are subject to chronic inflammatory, pathological processes and the external environment that affect their stability and biocompatibility with the ocular surface and adjacent ocular tissues. We compared the corrosion resistance property and tissue-implant reaction of titanium oxide (TiO(2)) with hydroxyapatite (HA) in artificial tear fluid and a rabbit skin implantation model. The dissolution properties of the implant surfaces were evaluated with scanning electronic microscope (SEM) and atomic force microscope (AFM). Tissue inflammatory reactions were evaluated by Hematoxylin & Eosin staining, avidin biotin peroxidase complex (ABC) immunoassay and immunofluorescence. SEM and AFM images showed that there was less pitting corrosion on the surface of TiO(2) implants compared with HA. TiO(2) and HA exhibited a similar pattern of foreign body capsule formation and inflammatory cellular responses. The Collagen I/Collagen III ratio of the TiO(2) capsule was higher than that of the HA capsule. TiO(2) implants possess a high corrosion resistance property both in vitro and in vivo and the inflammatory cellular response to TiO(2) is similar to HA. With regards to corrosion resistance and inflammatory tissue responses, TiO(2) appears to be a promising material for keratoprosthetic skirt devices.

Osteo-odonto-keratoprosthesis - a maxillofacial perspective

The OOKP (osteo-odonto-keratoprosthesis) is the treatment of choice for conditions like Stevens-Johnson syndrome, ocular cicatricial pemphigoid, trachoma, multiple failed grafts and chemical burns which are not amenable to penetrating keratoplasty. The OOKP is an autograft which replaces the cornea with a polymethacrylate cylinder mounted on a tooth-bone complex. The aim of this paper was to retrospectively analyze the records in 26 patients undergoing OOKP surgery between 2007 and 2011. The paper describes our experience with the procedure, with emphasis on its oral and maxillofacial aspects and management of associated complications. The aetiology of blindness in 23 patients was Stevens-Johnson's syndrome and chemical burns in three. Twenty-two patients had their maxillary canines, two had mandibular canines and two had maxillary first premolars as the choice of donor tooth. An oroantral fistula developed in four patients. One patient needed to undergo a surgical procedure for closure of the same. Roots of adjacent teeth were exposed in 12 patients. Twenty-four patients underwent both stages of the procedure with 19 being visually rehabilitated successfully. There was no improvement in the vision of four patients. One patient was lost to follow-up. Two patients have yet to undergo Stage 2.

Osteo-odonto keratoprosthesis: systematic review of surgical outcomes and complication rates

Case series on osteo-odonto keratoprosthesis (OOKP) published in English from 1950-June 2010 were identified in Medline/PubMed. Indications for surgery, visual acuity, anatomical survival, complication and repeat surgery rates were compared among the different studies. Our own case series is a retrospective review of all OOKP surgeries performed in our center from February 2004-July 2011. Eight case series including our own were systematically reviewed. Sample sizes ranged from 4-181 eyes. The most common indications for surgery were severe cases of Stevens-Johnson syndrome and thermal and chemical burns that were unamenable to other forms of surgery or had had previous surgical failure. Anatomical survival rate in all the studies was 87.8% (range 67-100%) at 5 years, and three studies showed survival rates of 81.0% (range 65-98%) at 20 years. Visual acuity was more than 6/18 in 52% (range 46-72%) of the eyes with OOKP surgery. The most common intraoperative complication was vitreous hemorrhage (0-52%) and the most common long-term blinding complication was glaucoma (7-47%). Endophthalmitis rates ranged from 2-8%. The most common repeat surgical procedure was mucosal trimming due to mucosal overgrowth at the optical cylinder and mucosal grafting for extrusion of the OOKP or mucosal ulceration. Of the available biological and synthetic keratoprosthesis, OOKP appears to be an excellent option for the treatment of end-stage corneal diseases.

Perioperative management of patients for osteo-odonto-kreatoprosthesis under general anaesthesia: A retrospective study

An osteo-odonto-keratoprosthesis (OOKP) procedure is indicated in patients with failed corneal transplant but having intact retina for visual improvement. We studied perioperative concerns of patients who underwent the staged OOKP procedure. This was a retrospective analysis of patients who underwent OOKP. The information regarding symptoms, associated comorbidities, perioperative events including anaesthetic management were collected. Eight patients (five females and three males) underwent the staged OOKP procedure. The median age was 18 years. The median weight was 45 kg. The median duration of loss of vision was 4 years. The aetiology of blindness included Stevens-Johnson's syndrome (SJS) (7) and chemical burn (1). Four patients had generalized skin problem due to SJS. All cases were managed under general anaesthesia, and airway management included nasotracheal intubation for stage I and orotracheal intubation for stage II. The median mallampati classification was I prior to OOKP stage I procedure while it changed to II at stage II procedure. Two patients required fibreoptic nasotracheal intubation. One patient had excessive oozing from the mucosal harvest site and was managed conservatively. In one patient, tooth harvesting was done twice as the first tooth was damaged during creating a hole in it. We conclude that OOKP requires multidisciplinary care. Anaesthesiologist should evaluate the airway carefully and disease-associated systemic involvements. The use of various drugs requires caution and steroid supplementation should be done. Airway difficulty should be anticipated, mandating thorough evaluation. Re-evaluation of airway is prudent as it may become difficult during the staged OOKP procedure.

Oral and maxillofacial surgeons' role in the first successful modified osteo-odonto-keratoprosthesis performed in the United States

Corneal disease constitutes the second most common cause of blindness and often leads to corneal damage or scarring. Several corneal scarring is a complex and difficult condition for ophthalmologists to manage. In the most severe cases, the scarring is accompanied by excessive dryness and keratinization of the ocular surface. Certain etiologies, including Stevens-Johnson syndrome, cicatricial pemphigoid, Lyell's syndrome, and chemical trauma to the surface of the eye, are responsible for the most severe cases. Traditional allogeneic corneal transplantation is not effective because of the significant scarring and dryness of the eye. To allow light and images to be focused on the retina, a keratoprosthesis is required to position a lens on the surface of the eye. One of the oldest and most effective types of keratoprosthesis, the osteo-odonto-keratoprosthesis (OOKP), was first described and documented in 1963 by Strampelli and subsequently modified by Falcinelli et al. The modified OOKP (MOOKP) is a unique prosthesis consisting of a lens fabricated from a polymethylmethacrylate (PMMA) cylinder and cemented to an autogenous graft composed of tooth and bone, traditionally termed the osteo-odonto lamina. In this context, lamina refers to a thin rectangular plate of tooth and bone (Fig 1). The MOOKP involves 4 procedures performed in 3 surgical stages.