What is the most incredible adaptation you have made in orthokeratology?
Above all, we are confident that our NightFlex orthokeratology lens will help you achieve the best results. Thanks to our Tear Volume Optimisation (TVO) technology, we are able to reshape even the most complex corneas.
Ortho-K lenses have been undergoing rapid development in recent years. They have become indispensable for both practitioner and patient. SwissLens offers a wide range of lenses (Myopia – Myopia Management – Hyperopia – Presbyopia), all of which benefit from the «TVO» (Tear Volume Optimisation) technology.
To shape the cornea, Ortho-K lenses must be able to exert a hydrostatic force on the cornea. This hydrostatic force is mainly generated in the reverse zone. To be effective, this zone must create an optimal tear lake (space between the lens and the cornea). TVO technology dynamically adjusts the height, the shape, and the width of this zone according to the geometric and optical parameters of the cornea:
Height of teardrop lake: high enough to generate hydrostatic force. A minimum height is even required for weak optical corrections.
Width and shape of the zone: obtain a sufficient volume of tear lake and a shape that will be progressively and specifically adjusted for strong correction (e.g. -9 dpt).
NightFlex Sph -6.00 Cyl -8.00
SwissLens offers a CL calculated with your parameters on a statistical basis. However, you may need to adjust it for an optimal Ortho-K effect.
The Jessen factor: Unity is the dioptre. This changes the radius of the central zone (without changing the other parameters of the CL). It ensures that the optical correction is good throughout the day. A too high Jessen factor induces more defocus (= increases the height of the tear lake via flattening of the central radius) but generates an over correction in the morning.
The compression factor: The unit is the micron. It allows you to adjust the sag of the reverse zone without modifying the other parameters of the CL. This factor inspects the pressure on the central zone without modifying the central radius, thus avoiding over-correction once the CL is removed.
The alignment zone inspects the centration of the lens and ensures that the lens sits firmly on the cornea. It can be adjusted – flatter or tighter – usually by changing its eccentricity in 0.01 steps.
Toric periphery: Often necessary for good seating from a difference of 0.3‑0.4 mm in corneal radius.
Other parameters allow you to fine-tune your fit even more, including the strength of the CL, the shape of the reverse zone or also the edge of the CL. The SwissLens team remains at your disposal for any further requests.