Scleral topography analysed by optical coherence tomography

Abstract

With the OCT device used in this study it was possible to measure scleral radii in eight different meridians. Scleral radii are independent of corneal topography and may provide additional data useful in fitting soft and scleral contact lenses.

Optical coherence tomography and scleral contact lenses: clinical and research applications

“…Since the introduction of OCT imaging, and the widespread use of preformed scleral lenses, impression moulding is relatively uncommon, and is typically reserved for complex ocular shapes (for example, extreme ocular deformation and post‐surgical eyes). A consistent finding from all studies examining the curvature of the anterior sclera using OCT imaging is that the sclera is significantly steeper temporally compared to nasally (Figure ), with substantially less variation between the nasal, superior and inferior quadrants . The curvature of the sclera varies with the ocular meridian examined, the distance from the limbus, age, the method used to fit a curve to the OCT image, and correction for instrument‐related optical distortion (Table ).…”

“…Scleral sagittal depth data is particularly useful for initial scleral lens selection (after factoring in additional depth to allow for adequate corneal clearance and lens settling), since measures of corneal radius of curvature only partially correlate with the back optic zone radius of the optimal scleral lens . Similarly, corneal astigmatism is of little use in initial lens selection because there is a weak relationship between corneal and scleral astigmatism for both magnitude and orientation …”

Relationship of placido corneal topography data with scleral lens fitting parameters

“…possible correlation between them. [7] A limitation of the present analysis is the fact that in the surgical group (subgroup 2) the corneal astigmatism is certainly affected by the surgical procedure, and therefore any relationship between corneal and scleral toricity is affected. This might explain why OC-SAG asymmetry derived from topography and lens landing zone toricity in post-surgical corneas are not related in the present sample.…”

“…The shape of the anterior eye, namely the scleral shape, has increasingly been studied over the last few years mainly because of the resurgence of ScCLs in the global market. Despite great advances in anterior segment (AS) imaging for ScCL fitting, such as anterior segment optical coherence tomography (AS-OCT) [7][8][9] and scleral topographers [10,11], their use to aid ScCL fitting remains restricted to few clinical practices around the world because of the current costs of this kind of technology. On the other hand, corneal topographers have become increasingly available in contact lens practice and are more accessible to clinicians.…”

Anterior eye surface changes following miniscleral contact lens wear

“…Our findings are in line with theirs, since the partial recovery in this study amounts to 77% of the total flattening. Scleral toricity [19,24,25] may result in an uneven distribution of the load for a lens with a spherical landing zone, like the ones used on this experiment, which might contribute to uneven compression across sectors. The orientation of extraocular rectus muscle insertions, eyelid forces and lid position have been designated as potential factors influencing scleral shape [24].…”