Seminars in Ophthalmology, 20:113–128, 2005 Copyright c Taylor & Francis Inc. ISSN: 0882-0538 DOI: 10.1080/08820530590931386 The Osteo-Odonto-Keratoprosthesis (OOKP) Christopher Liu Sussex Eye Hospital, Brighton, ABSTRACT The osteo-odonto-keratoprosthesis (OOKP), although described England, Aston University, Birmingham, England, and Kinki over 40 years ago, remains the keratoprosthesis of choice for end-stage corneal University, Osaka, Japan blindness not amenable to penetrating keratoplasty. It is particularly resilient Bobby Paul to a hostile environment such as the dry keratinized eye resulting from se- Sussex Eye Hospital, Brighton, England vere Stevens-Johnson syndrome, ocular cicatricial pemphigoid, trachoma, and Radhika Tandon chemical injury. Its rigid optical cylinder gives excellent image resolution and Sussex Eye Hospital, Brighton, England and All India Institute of Medical quality. The desirable properties of the theoretical ideal keratoprosthesis is de- Sciences, New Delhi, India scribed. The indications, contraindications, and patient assessment (eye, tooth, Edward Lee, Ken Fong, and buccal mucosa, psychology) for OOKP surgery are described. The surgical and Ioannis Mavrikakis anaesthetic techniques are described. Follow-up is life-long in order to detect Sussex Eye Hospital, Brighton, England and treat complications, which include oral, oculoplastic, glaucoma, vitreo- Jim Herold and Simon Thorp Royal Sussex County Hospital, retinal complications and extrusion of the device. Resorption of the osteo- Brighton, England odonto-lamina is responsible for extrusion, and this is more pronounced in Paul Brittain tooth allografts. Regular imaging with spiral-CT or electron beam tomography Sussex Eye Hospital, Brighton, England can help detect bone and dentine loss. The optical cylinder design is discussed. Ian Francis Preliminary work towards the development of a synthetic OOKP analogue Royal Sussex County Hospital, Brighton, England is described. Finally, we describe how to set up an OOKP national referral Colin Ferrett center. European Scanning Clinic, London, England KEYWORDS keratoprosthesis, OOKP, surgery, dry eye, allografts, electron beam tomog- raphy, ciclosporin, optics Chris Hull City University, London, England Andrew Lloyd University of Brighton, Brighton, England Osteo-odonto-keratoprosthesis (OOKP) surgery is a technique used to replace damaged corneae in blind patients for whom cadaveric corneal transplantation David Green, Valerie Franklin, and Brian Tighe is doomed to failure. It was developed some 40 years ago by Strampelli and uses Aston University, Birmingham, the patient’s own tooth root and alveolar bone to support an optical cylinder.1 England After a long interval the technique is finally gaining widespread recognition by Masahiko Fukuda and corneal surgeons worldwide as the treatment of choice for patients with end Suguru Hamada stage inflammatory corneal disease. In the case of a dry eye, no other device will Kinki University, Osaka, Japan work nearly as well. Christopher Liu thanks Professor GianCarlo Falcinelli and Mr. Michael Roper-Hall for their guidance. HISTORICAL REVIEW Address correspondence to Christopher Liu, Sussex Eye Hospital, Eastern Road, Keratoprosthetics, replacing damaged and opaque corneae with an artificial Brighton, England BN2 5BF. Tel: +44 (0)1273 606126; Fax: +44 (0)1273 693674; implant, dates back more than 200 years to Pellier de Quengsy, a French oph- E-mail: [email protected] thalmologist who proposed implanting a glass plate into an opaque cornea. 113 The first surgical case in a human was performed TABLE 1 Comparison of Devices. Clinical Studies Reported in PubMed and KPro Study Group Bibliography Including Articles in in 1855 with a quartz crystal implant developed by Languages Other Than English and Those not Indexed in Index Nussbaum. The prosthesis remained in the eye for Medicus (Updated May 2003) six months. Over the next 50 years, more attempts Clinical Follow-up were made to develop different keratoprostheses Device Papers Patients (Years) (KPros) and techniques (von Hippel 1877, Dimmer 1889, and Salzer 1895). Almost all the implants were Cardona 12 Champagne Cork 10 200 extruded and in the early twentieth century, interest Chirila (AlphaCor) 25 38 3 in keratoprostheses waned with the introduction of Choyce 5 107 penetrating keratoplasty. The early pioneers in the field Dohlman-Doane (Boston) 23 110 6 of penetrating keratoplasty included Elshnig in Prague Fyodorov 10 15 1.5 (1914), Filatov (1924), and Tudor-Thomas, who intro- Hydroxyapatite 2 4 2.5 duced the technique to the United Kingdom (1936). Legeais (PTFE) 26 24 2 OOKP 93 573 27 Penetrating keratoplasty went from strength to strength Parel-Lacombe 13 60 10 with Stocker in the 1950s and was accompanied by the Pintucci 20 128 19 introduction of steroids and fine needles and sutures. Seoul-type 2 7 2 Though more diseases became suitable for penetrat- ing keratoplasty, there were still conditions where the prospect of successful grafts was hopeless and so interest the corneal tissue so that they would intergrate better was renewed in keratoprostheses. Many pioneers were and be more compatible, such as the Strampelli OOKP involved in developing new KPros (Gyorffy, Sommer, using autologous tooth root and alveolar bone as a sup- Vodovozov, Stone and Herbert, Macpherson and port for a PMMA optical cylinder, cartilage (Casey) and Anderson, Binder and Binder, Fyodorov, Puchkovska, tibial bone (Temprano). Krasnov, Cardona, Castroviejo, de Voe, Choyce, Lund, Comparison between the various KPros can be dif- Dohlman, Casey, Donn, Buxton, Girard, Maroz, ficult as the published studies are often retrospective, Pintucci, Marchi, Legeais, Lacombe, Worst, Polack, are uncontrolled and have conflicting data for different Aquavella, Waring, Bertelson, Singh, Mohan, centers. The published literature is most extensive on Yakimako, Caldwell and Barraquer).2 OOKP surgery, which was the most number of patients and the longest follow-up (Table 1). However, it must be pointed out that many of the publications are not in WHAT IS THE IDEAL English, are not widely available, and several are not in KERATOPROSTHESIS? indexed journals. OOKP surgery differs in several ways from other In developing a KPro, the ideal device should be able techniques, multi-stage (usually two) surgery is re- to surpass the natural cornea by having an improved quired, and there is surgery both in the mouth and optical quality, with decreased aberrations and a speci- on the eye. Complications associated with all types fiable power. It should have excellent biointegration, of KPros are extrusion, glaucoma, retinal detachment provide resistance against infection and last the life- and retroprosthetic membrane formation. The OOKP time of the patient. It should also replicate some of the could uniquely withstand a hostile dry keratinized qualities of the cornea such as drug penetration and al- ocular surface. Falcinelli devised stepwise modifica- lowing intraocular pressure measurement.3,4 The types tions to the original Strampelli technique, which have of KPros currently available vary in design, especially re- led to improved visual results and retention of the garding the support for the optical cylinder. Most mod- device. A biconvex larger optic, preservation of the els use a non-biological skirt that is often porous e.g. periosteum, cryo-extraction of the lens and vitrec- all PMMA (Choyce, Dohlman-Doane [now known as tomy, the use of buccal as opposed to labial mucous the Boston KPro]), Dacron (Pintucci), hydroxy-apatite membrane, allograft using a non-erupted tooth, join- (Leon-Barraquer), expanded PTFE (Legeais) and hydro- ing two laminae together, and a posterior drainage gel (AlphaCor). KPros with biological skirts were also tube in refractory glaucoma5,6 are amongst Falcinelli’s developed, as they were thought to be closer related to innovations. C. Liu et al. 114 REFERRAL GUIDELINES FOR ration, iris adhesion, and degree of vascularization are OOKP SURGERY also noted. The depth of the anterior chamber, if vis- ible, is noted. The intraocular pressure is determined Indications digitally and a record is made as to whether the eye is Patients with bilateral corneal blindness resulting phakic, pseudophakic or aphakic. from severe end-stage Stevens-Johnson syndrome, oc- A and B scans are used for biometry to determine ular cicatricial pemphigoid, chemical burns, trachoma, the axial length, exclude pre-phthisis, confirming the dry eyes or multiple corneal graft failure may be consid- lens status, exclusion of retinal detachment, and with ered for OOKP surgery. The better, or only, eye should detection of gross glaucomatous cupping. have poor vision, such as PL, HM or at best CF. One eye Assessment of a patient for OOKP also involves an only will be rehabilitated. In suitable cases, there would assessment of the general medical and psychological sta- be no need to go through unsuccessful penetrating ker- tus of the patient. The patient must be fully informed of atoplasty with or without limbal stem cells transplanta- the procedures and risks. The “side effects” and possible tion and amniotic membrane grafting beforehand. complications are described below. Contraindications Oral Assessment Patients who are happy and managing with their level The oral assessment must take into account both the of vision, children under the age of 17, eyes that have buccal mucosal graft donor site and a selection of an no perception of light, evidence of phthisis, advanced appropriate