The genetic mutation causes abnormalities of the α1 or α2 chain of type I collagen. As a result, the collagen fibrils fail to mature to their normal diameters.
Patients with osteogenesis imperfecta are susceptible to brittle bones and multiple skeletal fractures. Hearing loss is common; the prevalence ranges from 50% to 92% in some studies. Hearing loss may be conductive, mixed, or sensorineural and is more common after adolescence. Patients are also predisposed to brittle teeth. Ocular manifestations include blue sclera (Fig 8-11) and reduced central corneal thickness (average of 450 μm). The blue sclera is present throughout life in type I osteogenesis imperfecta, but fades within the first few years of life in the other 3 types. Other rare ocular findings include optic nerve damage due to fractures in the calvarial bones, keratoconus, and megalocornea. Table 8-6 summarizes other conditions associated with blue sclera.
Treatment with oral bisphosphonates reduces bone resorption, and aggressive orthopedic management of fractures is indicated. Low-impact exercise might help preserve bone and muscle integrity.
Figure 8-11 Clinical photograph showing blue sclera in a patient with osteogenesis imperfecta.
(Courtesy of Stephen E. Orlin, MD.)
Table 8-6 Conditions and Medications Associated With Blue Sclera
Excerpted from BCSC 2020-2021 series: Section 10 - Glaucoma. For more information and to purchase the entire series, please visit https://www.aao.org/bcsc.