Lente sclerale a geometria oblata
After refractive surgery for the correction of myopia, the central cornea is flatter than the surrounding peripheral area, assuming an oblate profile (photo of the topography: the blue area represents the flattest part of the cornea. The cornea becomes progressively steeper. The yellow and orange areas represent the steepest areas).
In some cases it is necessary to apply rigid lenses to correct residual myopia, solve the problem of halos and glare during night vision, or correct the corneal irregularity caused by the surgery.
By applying a prolate scleral lens, which is steeper in the center and becomes increasingly flatter towards the periphery, in the central corneal area there is an excessive post-lens liquid reservoir, just because the cornea in that area is flatter and the lens is steeper. The best solution in these cases is to apply a lens that follows the corneal profile. An oblate lens, flatter in the center and steeper in the peripheral area (similar to the treated cornea), allows for a homogenous thickness of the liquid that forms between the lens and the cornea in all areas of the cornea, central and peripheral (see photos with the uniform thickness of the liquid colored in green/yellow).
In these cases, the oblate scleral lens prevents the onset of various issues related to the fitting, allows to maintain corneal health, is more stable and better centered on the eye, and offers greater comfort during hours of use.