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.

Background The WHO's Vision 2020 global initiative against blindness, launched in 2000, prioritises children. Progress has been hampered by the global paucity of epidemiological data about childhood visual disability. The British Childhood Visual Impairment and Blindness Study 2 (BCVIS2) was undertaken to address this evidence gap. Methods UK-wide prospective population-based observational study of all those aged under 18 years newly diagnosed with visual impairment or blindness between Oct 1, 2015 and Nov 1 2016. Eligible children were notified simultaneously but independently by their managing ophthalmologists and paediatricians via the two national active surveillance schemes, the British Ophthalmic and Paediatric Surveillance Units. Standardised detailed data were collected at diagnosis and one year later. Incidence estimates and relative rates by key sociodemographic factors were calculated. Descriptive analyses were undertaken of underlying ophthalmic disorders and nonophthalmic comorbidities. FindingsOf 784 cases, 72% had additional non-ophthalmic impairments/disorders and 4% died within the year. Annual incidence was highest in the first year of life, 5•2 per 10,000 (95% CI 4•7-5•7) with cumulative incidence by 18 years of 10•0 per 10,000 (95% CI 9•4 to 10•8). Rates were higher for those from any ethnic minority group, the lowest quintile of socio-economic status, born preterm or with low birthweight. Only 44% had a single ophthalmic condition: disorders of the brain/visual pathways affected 48% overall. Prenatal or perinatal aetiological factors accounted for 84% of all conditions. InterpretationBCVIS2 provides a contemporary snapshot of the heterogeneity, multi-morbidity and vulnerability associated with childhood visual disability in a high income country, and the arising complex needs. These findings will facilitate developing and delivering healthcare and planning interventional research. They highlight the importance of including childhood visual disability as a sentinel event and metric in global child health initiatives.

Aims: To study the long term toxic effects of intraocular benzalkonium chloride (BAC). Methods: 19 patients exposed to intraocular BAC preserved viscoelastic during cataract surgery in February 1999 developed severe striate keratopathy immediately postoperatively. 16 patients, including two who underwent penetrating keratoplasty, were studied in the period April to June 2000. Ocular symptoms, visual acuity, biomicroscopy, intraocular pressure, dilated funduscopy, specular endothelial microscopy, and corneal pachymetry findings were recorded. The corneal and iris specimens of the two patients who underwent keratoplasty were studied by light, transmission, and scanning electron microscopy. Results: Six males and 10 females, aged 64-98 years, were studied 14-16 months postoperatively. All patients were symptomatic. 12 patients had best corrected visual acuity of 6/12 or better and four patients of between 6/18 and 6/60. Five patients had corneal epithelial oedema and 11 had Descemet's membrane folds. The central corneal thickness, 620 (SD 71) µm, in affected eyes was significantly higher (p<0.005, two tailed paired t test) than that of the contralateral eyes, 563 (SD 48) µm. The endothelial cell density was significantly lower (p<0. . There was no significant difference in the coefficient of variation of cell size between the two eyes (p=0.3, two tailed paired t test). Two corneal specimens displayed morphological features of bullous keratopathy and other nonspecific abnormalities. Extracellular melanosomes were present in a portion of the iris of one case. Conclusion: BAC is toxic to the corneal endothelium when used intraocularly, leading to severe striate keratopathy. This cleared in most cases but left varying degrees of residual stromal thickening in all eyes. If penetrating keratoplasty is required the results are excellent.

Upper eyelid gold weight implantation causes an increase in corneal astigmatism, predominantly in the vertical axis, which appears to be reversible on removal of the gold weight.

To our knowledge, we are the first to report histopathologic findings of explanted high-density porous polyethylene implants from the lower eyelid in humans. Although this study shows that Medpor LES does biointegrate, we advocate using it sparingly due to associated complications such as exposure, poor stability, and contour.