The breakthrough lenses for irregular corneas

    Fitting irregular corneas has shaped my life’s work as founder and inventor of the highly regarded ROSE K contact lenses for keratoconus. 

    When I started out as an optometrist, only bi-curve corneal rigid lenses were fitted for keratoconus – a condition which causes an irregular-shaped cornea. It meant finding the right fit for each patient was often a long and complicated journey, so I dedicated my career to developing an easier and more efficient solution.   

    I created the ROSE K lenses to provide simplicity, comfort and ultimately greater vision for patients. More than 30 years on from their first iteration and working with Menicon, the ROSE K lenses are one of the most recognized brands for the irregular cornea. Today, they are fitted in over 90 countries globally.

What is keratoconus?

    Keratoconus is a condition that can severely hamper a patient’s vision – it has been compared to viewing a street sign through a car window while driving through rain. This is caused by a distortion of the cornea, the clear, dome-shaped surface of the eye. Keratoconus happens when the cornea thins and bulges out into a cone shape, resulting in blurred vision and may cause sensitivity to light and glare.1

It's unclear what causes keratoconus but the condition typically affects both eyes and it is generally diagnosed in young people and managed over time as it progresses. But it’s not unusual for patients in their 40s and 50s to be diagnosed.2

    While the condition is thought to affect around one person per 1,0003, incidences can vary greatly geographically and within different ethnicities.4 Working as an optometrist in New Zealand, I saw many more keratoconus patients than a standard practice. In fact, a recent study of high school students in New Zealand found the incidence rate is one person in 191.5 It meant keratoconus very quickly became a special interest for me when I opened my first practice in 1969. 

The ROSE K journey

    The solution for keratoconus patients is usually to wear glasses or soft lenses at first then, as the condition develops, patients may be fitted with special rigid gas permeable (RGP) lenses. These lenses require careful fitting to the cornea, which can develop into different shapes at different stages of the disease. 

    When I began seeing keratoconus patients I had very little knowledge of how to fit lenses for this condition accurately. But over the next decade, I gained a good understanding of the designs that worked and began designing and making lenses tailored to the individual patient.

    Although successful, the process was time consuming and often required three or four different lenses before finding the final fit. There had to be a better way. 

    Working with a local lab, I started to develop a model and fitting system that reduced the variables so fitters could relatively easily follow ‘the system’ and achieve a reasonable success rate even if they were not experts. The problem was that secondary curves were polished on by hand which led to variable results. It wasn’t until the lab invested in a computer lathe, the first in New Zealand, that I was able to make micro changes that were repeatable. 

    Six years later, after testing over 700 lenses and 12 different designs, I produced a set of 26 lenses from which all patients could be fitted.

    The first ROSE K lenses were launched in New Zealand in 1990 and before long, they received FDA approval for the US too.

    Since Menicon acquired the ROSE K portfolio in 2008, I’ve conducted further research and used advances in technology to push the original lens designs further. We now have a comprehensive family of lenses, each with unique properties, that can adapt to the nuances of the different types of irregular corneas.

A family of lenses for a world of irregular corneas

The range’s most widely prescribed: ROSE K2

The ROSE K2 lenses treat oval-shaped corneas, the most prevalent type of corneal shape associated with keratoconus, affecting up to 70% of all irregular corneas.6 The ROSE K2 lenses are one of the most widely prescribed keratoconus lenses in the world. Its multi-spherical posterior design has aberration-control aspheric optics across the back and front optic-zone diameters to add optimum focus. They’re available in several asymmetric options including a toric lens design.

For nipple cone-shaped corneas: ROSE K2 Nipple Cone (NC) 

The ROSE K2 NC has been developed for those with advanced and moderate nipple cone-shaped corneas. Generally affecting 5% to 10% of those with irregular corneas, nipple cones refer to a small, near-central cone in the cornea.7 Our lens is shaped to correct distortion and improve peripheral vision using a small aspheric back optic zone diameter that decreases as the base curve steepens, and a very rapid peripheral flattening from the back optic zone.

Post graft recovery support: ROSE K2 Post Graft (PG)

    Specifically designed for patients who have undergone keratoplasty (corneal transplants), these lenses help postoperative recovery and improve vision. The ROSE K2 PG lens has a multi-spherical posterior design with some reverse-curve geometry and aberration-control aspheric optics across the back and front optic-zone diameters.

A larger lens: ROSE K2 Irregular Cornea (IC)

    These lenses use the same systematic fitting approach of the ROSE K2 design but feature a larger overall diameter. The ROSE K2 IC has secondary applications for very decentered oval cones, providing a strong alternative for irregular corneas where other corneal designs have failed. 

For early to moderate irregular corneas: ROSE K2 Soft 

    An alternative to RGP lenses, the ROSE K2 Soft is a daily wear soft lens for irregular corneas. They can be made using silicone hydrogel as a three-month replacement lens or using hydrogel materials as a six or 12-month replacement lens. They’re suitable for new contact lens wearers with irregular corneas, early to moderate irregular corneas, those with an intolerance to RGP lenses, or for those playing sport.

A corneo-scleral lens: ROSE K2 XL

    This lens is for patients who cannot be successfully treated by fitting a lens within the limbus. It is frequently used for keratoconus, PMD, and post-surgery. The ROSE K2 XL follows the same systematic fitting system advocated for the four other ROSE K2 corneal designs. It is designed to be extremely easy to fit, even for fitters who have not used a corneo-scleral design before.

Special option lens enhancers: Toric Periphery (TP), Asymmetric Corneal Technology (ACT), Quadrant Specific Edge Lift (QSEL)

    In addition to the six designs listed above, the lenses can be further customized and tailored to the patient through a variety of lens enhancing options. The most common option used is a TP (toric periphery) to address corneal and scleral astigmatism.

    ACT (asymmetric corneal technology) enables the practitioner to adjust the lens fit in half of the lens by either tucking the lens inwards or outwards (reverse ACT). QSEL (quadrant specific edge lift) allows the practitioner to adjust only the edge lift in a particular lens quadrant. ROSE K lenses can be optimized to address any asymmetry of the eye with these options independently or through any combinations. 

Customizing ROSE K for better vision

    When I set out to create ROSE K lenses, I wanted any fitter who could fit a corneal lens to be able to fit keratoconus. The process needed to be more efficient and less time consuming for both fitters and patients. By achieving this goal, fitters throughout the world – even those with minimum fitting skills – would have the opportunity to fit irregular corneas with an excellent chance of success.

    All ROSE K lenses follow a simple five-step fitting method and each of our ROSE K lenses operates with a simple peripheral fitting system, eliminating the need for the fitter to state complex secondary radii and diameter modifications.

    Before fitting, it is critical to select the correct lens design for the type of irregular cornea being fitted. The ROSE K2 is suitable for oval-shaped corneas, while patients with nipple cones require the ROSE K2 NC lenses. For pellucid marginal degeneration, keratoglobus or LASIK-induced ectasia, consider the ROSE K2 IC as the first option.

    In post-surgical cases the ROSE K2 PG design should be the first choice. The ROSE K2 XL corneo-scleral lens is the next option when none of the above lenses achieve a successful outcome, and they can even be worn by patients with regular corneas when the patient needs a more comfortable fit. 

    The design choice is best based on corneal topography maps, which provide a detailed understanding of the curves and diameter of the cornea.

    Our new fitting guide can help you choose the best lens solution for your patient as well as understand how our comprehensive fitting process works.

The blossoming future of ROSE K

The ROSE K lenses have led the way in transforming the vision of patients with irregular corneas, and there are no plans to slow down. 

    We’re continuing to innovate. In January 2023, we launched our brand-new ROSE K2 XL Oblate lens for patients with flat to extremely flat corneas, providing even more irregular cornea patients with a comfortable precision lens.

    Oblate corneas frequently occur following grafts, photorefractive keratectomy and laser surgery interventions. The ROSE K2 XL Oblate lenses are designed to mimic more accurately the abnormal corneal shape post-surgery, reducing the tear layer thickness over the pupil by 200 to 250 microns to provide better tear exchange and more comfort for daily wear. 

    It’s another step closer to providing a complete range of lenses so that all cases of irregular cornea can be fitted from the ROSE K family. It’s my dream to provide better vision for every type of irregular cornea and I’m working on making it a reality.


Paul Rose

Inventor of ROSE K contact lenses

Paul Rose, an optometrist from Hamilton, New Zealand, is the inventor of ROSE K lenses. When he finished university and started fitting irregular corneas, he realized how complicated it was to find the perfect lens for each patient. He began the development on the ROSE K keratoconus lens in the 1980s and continues to work on the full ROSE K family today.


  1. Mayo Clinic, Keratoconus, accessed February 2023.
  2. Millodot Michael et al. Effect of ageing on keratoconic corneas,  J Optom. 2016 Apr-Jun; 9(2): 72–77.
  3. Hashemi Hassan et al. The prevalence and risk factors for keratoconus: A systematic review and meta-analysis, Cornea. February 2020; 39(2):p 263-270.
  4. Gokhale Nikhil S, Epidemiology of keratoconus, Indian J Ophthalmol. 2013 Aug; 61(8): 382–383.
  5. Papali’i-Curtin Alastair et al. Keratoconus prevalence among high school students in New Zealand, Cornea. July 2019; 38(11):1.
  6. https://www.roseklens.com/practitioners/about-the-lenses/
  7. Menicon data on file
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