Rose K

It’s Easy Fitting Keratoconus

Dr. Paul Rose further refined the Rose K lens to take into account the unusual corneal shapes of keratoconus patients, which require abnormal curves on the back of the lens to fit the cornea optimally. This new lens is known as the Rose K2 lens.

With normal corneas the shape does not change dramatically from the center out, but tends to change evenly in predictable amounts, and therefore with normal corneas the back surface of the lens can be designed with small incremental changes (e.g. eccentricity) over most of the lens with a peripheral curve at the edge. Usually, this will achieve reasonable alignment with the cornea and a good fit.

However, to achieve optimum alignment with the cornea in keratoconus patients, many curves are required on the back surface of the lens, and adjacent curves are often very different. Particularly in steeper cones, several curves are often required within the patient’s pupil zone to achieve a good fit over the central area of the lens. Unfortunately, each one of these curves gives rise to a slightly different focal point at the back of the eye. This causes the patient to experience ghosting around the object that they are viewing (like a TV with poor reception) and this is worse the bigger the pupil is because more curves on the back surface of the lens come within the patient’s pupil zone. Therefore night driving where the pupil is larger is very difficult for keratoconus patients. These multiple focuses are called aberrations.

The Rose K2 lens minimizes these aberrations by applying very small changes to the curves on both the front and back of the lens in an attempt to bring the light passing through the lens within the pupil zone to a single point.

Following extensive trials, the best combination of aberration control curves have been developed for computerized digital lathes to cut these very complex curves for the Rose K2 lens to give the best focus.

The Rose K2 lens marks a significant improvement in optical quality over the original Rose K design and is available from most Rose K manufacturers and distributors internationally.

Standard Lens Designs

Standard lens designs with fixed optical zones (OZ) do not ideally fit the cone shape of keratoconus patients. This figure to the left shows a standard lens that will yield unwanted pooling at the base of the cone and peripheral bearing that can seal off and cause corneal problems.

Smaller Optic Zones

The figure to the right shows how a smaller optical zone allows a uniform fit for the cone contour. The design results in reduced tear pooling at the base of the cone and shows an even distribution of tears under the lens.

The Rose K system has set optical zones to maximize vision while maintaining good corneal health.


Cornea Style
Design Type
Lens Parameters
Base Curve –
Sphere Power –
Cylinder Power –
Axis –
Diameter –

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