A new eye imaging study has uncovered detailed changes in the structure of the sclera in people with severe short sight, offering fresh insight into the development of sight threatening complications linked to pathologic myopia.
Researchers used a specialised technology, polarisation sensitive optical coherence tomography (PS-OCT), to visualise collagen fibre orientation in the white outer coat of the eye. The findings suggest the method could help clinicians better understand, and eventually target, deformities associated with high myopia, including dome shaped maculopathy (DSM).
Distinct fibre patterns in highly myopic eyes
The case series examined 89 eyes from 72 adults with high myopia, defined as a refractive error of ≥6 dioptres or an axial length of 26.5 mm or more. Participants, most of whom were women (70.8%), had a mean age of 61.5 years. Imaging was carried out at a single clinic over two months in 2019, with analysis continuing through to late 2023.
More than half of the eyes studied (52 eyes, 58.4%) did not have DSM. In these, PS-OCT revealed two characteristic fibre orientations. Low density radially arranged collagen fibres were seen in the inner sclera, while the outer layer displayed densely packed fibres aligned vertically.
Among eyes with simple high myopia, only the inner sclera could be visualised. However, in 39 eyes with more advanced pathologic myopia, images showed the full thickness of the sclera and confirmed the vertical orientation of fibres in the outer coat.
Structural disruption linked to dome shaped macula
DSM was present in 37 eyes (41.6%), with most cases showing horizontal dome shapes (73.0%). In these eyes, researchers observed clear disruption of fibre organisation. Inner scleral fibres became aggregated and thickened at the site of the dome, while the vertically oriented fibres behind them appeared compressed and thinner rather than enlarged. Areas of low birefringence, indicating reduced fibre organisation, were found within the domes, highlighting a shift in collagen architecture that may contribute to deformation of the retina overlying the sclera.
Potential for earlier intervention
The authors say that detecting these changes could be crucial in preventing vision loss. Pathologic myopia is known to cause serious complications, such as staphyloma and retinal damage, and often progresses silently.
Reference
Ohno-Matsui K et al. Polarization-sensitive OCT imaging of scleral abnormalities in eyes with high myopia and dome-shaped macula. JAMA Ophthalmol. 2024;142;(4):310-319.
