KeraKone is a rigid contact lens for keratoconus that takes advantage of a well-established approach to keratoconic lens fitting through adaptive design and optic zone control. 

KeraKone is a multi-spherical back surface Keratoconus lens and takes advantage of a well-established approach to keratoconic lens fitting through adaptive design and optic zone control.

KeraKone has three standard peripheral systems – STANDARD, INCREASED and DECREASED. These three options should fit the majority of keratoconic patients.

Aims and Ideal Fit

  • The aim of fitting KeraKone is to fit a lens which provides good acuity whilst being comfortable and maintaining corneal integrity.
  • The ideal fit (Fig. 1) will have:
    • Light feather touch at the apex of the cone
    • A small amount of apical clearance is acceptable
    • As close to alignment as possible over the cornea
    • Edge clearance producing a fluorescein band of 0.5 to 0.8mm.
    • Good centration

Figure 1 – Ideal Fit


Trial Lens Selection

  • Topography fitting:
    • Start with a trial lens which has a base curve close to the measurement at the temporal 4mm position
  • Keratometer fitting:
    • Start with a trial lens 0.20mm steeper than mean K

Fitting and Troubleshooting

  • We recommend the use of a short-acting topical anaesthetic to reduce tearing and enable accurate fluorescein assessment.
  • After instilling fluorescein, wait at least 2 minutes for the excess fluorescein to dissipate before assessing the fit, or a false fitting pattern may be observed.
  • Central fit assessment:
    • Aim for light feather touch at the apex.
    • Excessive apical clearance (Fig. 2) may result in reduced visual acuity; flatten the base curve until very light apical touch can be discerned.
    • Excessive apical bearing (Fig. 3) increases the risk of corneal abrasion and scarring; steepen the base curve until light feather touch is seen.

 Figure 2 – Excessive Apical Clearance

Figure 2 – Excessive Apical Bearing


Peripheral fit assessment:

  • There will usually be some toricity to the edge clearance so it should be assessed along both the flat and steep meridians.
  • Excessive edge lift (Fig. 4) will result in a lens which moves too freely.
  • Inadequate edge clearance (Fig. 5) will be seen as a fluorescein band of less than 0.5mm and a dark ring of touch near the edge of the lens. The lens may be uncomfortable and may not move freely.


Edge profile adjustments:

  • Fitting sets are supplied with standard edge lift
  • 2 steps of increased and 2 steps of decreased edge lifts are available
  • Each increment has been calculated to produce a clear and noticeable change in the fit


Lens Diameter:

  • The standard diameter is 8.7
  • Lens diameter should only need to be altered in advanced cones or very toric corneas
    • If the lens is riding low, increase the total diameter
    • If the lens is riding high, decrease the total diameter

Lens Power:

  • Over-refract initially using 1D steps and then refine using 0.50D and 0.25D steps


Figure 3 – Excessive Edge Lift


Figure 4 – Inadequate Edge Clearance

Fig. 4 and Fig. 5 courtesy of Keith Tempany FBDO CL FBCLA.

Design Number of Lenses BCOR Diameter Power
KeraKone 24 5.10 to 7.40mm (0.10mm steps) 8.70mm -23.00 to -2.00D (in 1.00D steps)

Why KeraKone 2?

  • Suitable for all keratoconic profiles
  • Aberration control optics providing excellent visual acuity
  • Reduced flare and glare
  • Extensive base curve and diameter range
  • Cost effective
  • Familiar fitting strategy
  • Indications:
    • First fit for irregular corneas such as KC and Post Lasik Ectasia
    • Refits from other leading designs
    • When soft KC lenses are no longer adequate


Optimum and Boston
Dk Dependent on material
Tint Dependent on material
Base Curve 4.50 to 7.50mm in 0.05mm steps
Diameter 8.70mm (standard), 8.10mm, 8.40mm, 9.00mm, 9.30mm
BVP +25.00D to -25.00D
Edge Profile Standard, 2 steps available flatter and steeper

Contact Lens Wear Without Compromise

Using breakthrough manufacturing technology, Tangible Hydra-PEG bonds a 40nm hydrophilic coating to the surface of specialist contact lenses, significantly increasing wettability and lubricity.

The result? Happy patients who can enjoy a life of comfortable contact lens wear free from compromise.

Tangible Hydra-PEG is available with all No7 GP lenses. Just ask our Customer Care team to add Tangible Hydra-PEG when you place your next order.

Perfect for all GP patients, Tangible Hydra-PEG offers:

Increased wearing times

Improved ocular health

Superior surface properties

Improved wearing experience

“Brilliant! I’ve gone from using eye drops 5 times a day to 0...”

Keratoconus RGP wearer | 50+ years


Lens preference

Research shows that 70% of patients prefer a Tangible Hydra-PEG coated lens to their habitual, uncoated lens.


End of day comfort

67% of patients said they prefer a lens coated with Tangible Hydra-PEG than uncoated.


Dry eye comfort

When asked about comfort, dry eye patients rated lenses coated with Tangible Hydra-PEG ‘8 out of 10’, compared to ‘3 out of 10’ for uncoated.


70% prefer a Tangible Hydra-PEG coated lens

No7 Recommends - Ote Fine

All-in-one comfort solution for RGP contact lenses

Manufactured using the highest grade ingredients and exclusive to independent opticians, Oté Fine is the complete solution for all your RGP patients. Oté Fine is perfect for your EyeDream Ortho-k wearers too.

Kevin Taylor

Technical Director

We have a dedicated technical support team, headed by Kevin, with decades of experience ready to help and advise you on any fitting issues. If you need support, please call: 


01424 850620

Frequently Asked Questions

We’re here to help. If you can’t find the answer to your question, why not give us a call. Our offices are open Mon-Fri 9:00 – 17:30

Can I order these lenses empirically
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How long will it take to manufacture lenses
Standard delivery time is 4 days. However, we are able to accomodate more urgent orders. If you need to receive your lenses more urgently, please tell us the the time of order.
What is the returns policy?
We offer a standard 90 day full refund (minus handling charge) on Quasar lenses.

We are here to help

Drop us a line anytime, and one of our customer service team will respond to you as soon as possible.