Background:
Osteogenesis imperfecta (OI) is a rare genetic disorder characterized by brittle, fracture-prone bones. Individuals with OI may also have extraskeletal manifestations including ocular complications. Blue sclera is the most common ocular manifestation of the disease. Due to abnormal collagen type I fiber development or orientation, the sclera might be thinner in OI. This study investigated the scleral structure in individuals with OI using polarization-sensitive optical coherence tomography (PS-OCT).

Methods:
Three individuals with different types of OI and seventeen healthy participants who underwent ophthalmologic screening and PS-OCT scanning were included in the analysis. The birefringence of two regions of orthogonally oriented collagen was measured, along with the thickness of the radially oriented collagen layer. PS-OCT revealed similar collagen fiber orientation of the first scleral layer in OI participants and healthy controls.

Results:
The sclera demonstrated a circular ring around the optic nerve head and an upper radial layer in the remaining measured region. Although some measurements were within ±2 standard deviations of the mean value observed in healthy participants, OI participants appeared to have a reduced birefringence of the radially oriented layer when compared to the control group (OI participant 1 ODS: 0.34 °/µm, OI participant 2: ODS 0.26 °/µm, OI participant 3: OD: 0.29 °/µm, OS: 0.28 °/µm, healthy controls: ODS 0.38 ± 0.05 °/µm).

Conclusion:
These findings suggest that OI may alter the first scleral layer microstructure. This layer’s reduced birefringence suggests abnormalities in collagen organization and composition which could contribute to the ocular phenotype in OI.