Researchers have recently discovered that the cornea isn’t the only structure affected by keratoconus. The sclera also shows a degree of asymmetry that correlates with corneal parameters such as the flattest and steepest keratometry.
This study included 20 eyes of 15 keratoconus patients with no previous specialty lens experience or ocular surgery history. A team obtained corneal images and 3D corneoscleral maps. They calculated the sagittal height at the central cornea (annulus of 0mm to 4mm radius), peripheral cornea (annulus 4mm to 6mm radius) and sclera (annulus 6mm to 8mm radius), flattest and steepest regions of each annulus and circumferential scleral asymmetry. They then evaluated the correlation between these corneal parameters.
The researchers reported that the flattest and steepest keratometry measures were correlated with scleral asymmetry in keratoconus. In contrast, they noted that anterior astigmatism showed poor correlation with the level of scleral irregularity. They added that other disease-specific parameters pertaining to the posterior corneal curvature and thickness were not correlated with scleral asymmetry. They also found that the steepest regions of the central cornea, peripheral cornea and sclera tended to share a common angle.
Dhaese SE, Kreps EO, Consejo A. Scleral shape and its correlation with corneal parameters in keratoconus. Cont Lens Ant Eye. September 13, 2020. [Epub ahead of print].