Clinical Importance of Sagittal Height in Orthokeratology Lens Fitting

In orthokeratology (Ortho-k) lens fitting, stable centration of the lens and sufficient tear layers are essential for maintaining persistent vision correction and healthy corneas. However, accurate Ortho-k lens alignment is not easy; thus, sagittal height (Sag) adjustment is required. The Sag describes the vertical distance of the cornea at a given point. The same principle applies to a contact lens. The Sag of the peripheral zone is the primary concern in lens alignment. In this review, the clinical importance of Sag and how to approach it in challenging cases are investigated for accurate Ortho-k lens fitting.