The Osteo-Odonto-Keratoprosthesis (OOKP)

Abstract

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.

Optical Functional Performance of the Osteo-Odonto-Keratoprosthesis

“…Our inclusion criteria were: Stable uncorrected visual acuity better than 20/60 for ten months or more after surgery and who had been assessed using previously published guidelines. 2 We recruited ten patients for this study. All patients were implanted with the UK design of the OOKP optical cylinder.…”

“…2 Pre-operative diagnoses included Stevens-Johnson Syndrome (n=6), alkali chemical injury (n=1), graft versus host disease (n=1), linear IgA disease (n=1) and LOGIC syndrome (n=1).…”

“…[4][5] The technique has been previously described in more detail. 2 OOKP surgery is unique in that the single optical cylinder replaces all of the optical elements of the eye. The optical power, originally provided by the cornea and lens, is replaced by the anterior and posterior surfaces of the PMMA cylinder.…”

“…This is because the overall length and anterior cylinder diameter have more significant clinical constraints. 2 Minimal data are available about visual performance and optical properties of the OOKP. The aim of our study was therefore to assess the optical performance of the current generation OOKP device in vivo and assess its correlation with visual function reported subjectively by the patient.…”

“…[1][2][3] The OOKP is used in the treatment of corneal blindness in diseases with severe ocular inflammation and dry eye (such as end-stage Stevens-Johnson syndrome (SJS), ocular cicatricial pemphigoid, chemical burns, trachoma, dry eyes or multiple corneal graft failure) and has been shown to have good long term retention rates. [4][5] The technique has been previously described in more detail.…”