What causes the blue sclera in osteogenesis imperfecta oi?

Uveal "show": Oi causes a thinning of the sclera, the white coat of the eye. It allows the blue-gray uveal layer beneath to be visible through the sclera.

See below:: The sclera is the white outer coating of the eye and contains mainly collagen. In oi sufferers(some-not all) due to the collagen deficiency the sclera is thinner and becomes translucent allowing the underlying tissue to show through. Source(s): http://www.Brittlebone.Org/about-osteogenesis-imperfecta.Htm http://www.Thetech.Org/genetics/ask.Php?Id=93.

Thin sclera: Osteogenesis imperfecta amongst its other problems, produces a thinning of the white outer coat of the eyeball, the sclera. Because of this the dark inner lining, the uvea, adds its coloration to light striking the thinned sclera and the result is a blue color. The condition does not actually infuse the sclera with blue - it is an optical effect.