Keratoconus is degenerative condition affecting the cornea – the front transparent window at the front of the eye. The condition causes a thinning to the cornea, this causes the shape of the cornea to change to a pointed, more conical shape. As a result, vision becomes blurry and patients usually notice streaks or haloes – particularly at night.
Keratoconus affects 1 in 1000 people and is more common in people of Asian decent.
How is it Best Detected?
Earliest detection is possible with a combination of corneal topography, anterior segment OCT and aberrometry. Corneal topography measures thousands of points on the cornea to accurately calculate the shape of the cornea. Cornea pachymetry enables our Optometrists to calculate the thickness of the cornea. Finally, aberrometry allows our practitioner to measure subtle optical errors responsible to streaks and haloes.
Our keratoconus consultations will allow us to monitor the progression of the condition in order to advise you on the best treatment options.
Anterior Segment OCT
OCT or Optical Coherence Tomography is widely regarded as one of the single biggest innovations in ophthalmic imaging. The technology allows us to taken multiple sections through the cornea in order accurately visualise its profile and thickness in microscopic detail.
We also use anterior segment OCT to show how scleral lenses avoid touching the cornea.
Scan of a Cornea with Keratoconus
If you are not having any difficulties with your vision in glasses then the sensible choice is to keep wearing an up-to-date glasses prescription. However, most keratoconic patients cannot see sufficently well in spectacles due to the irregular shape of the cornea.
If you can’t see well in glasses, the best option is to wear precisely designed keratoconus contact lenses. Although soft keratoconus lenses are available they do not correct vision particularly well, therefore the most effective lenses are rigid lenses. Rigid gas permeable lenses are also availble in a number of designs and our Optometrists will determine the best design during your keratoconus contact lens fitting.
Our practice is not restricted to using any particular brand. In fact, we able to fit all types of designs and lens types. The most popular ones are:
Soft Contact Lenses
Ideal for early keratoconus where there is no significant corneal irregularity. Soft lenses are comfortable and offer a great deal of flexibility. As they flex on the eye they are not suitable if you have night-time vision problems.
Hybrid Contact Lenses
Ideal for moderate keratoconus where rigid lenses are not tolerated. The outer skirt of the lens is soft (to provide comfort) and the centre is made from a rigid lens material (to correct the corneal irregularity).
Corneal GP Lenses
These are rigid lenses that sit on the cornea. They provide better vision correction than soft lenses. RGP lenses are suitable for moderate keratoconus. These are probably the most commonly fitted lens.
Semi / Mini Scleral
Semi and mini scleral lenses are gas permeable and rigid. They are comfortable and provide excellent vision. Suitable for moderate and advanced keratoconus. See our post on KeraFit lenses.
Can Keratoconus be Stabilised?
If we find that your keratoconus progressing, we will recommend you have corneal cross linking treatment. This treatment is available on the NHS and we will arrange a referral (either through the NHS or privately). Corneal cross linking is not suitable for everyone. If your keratoconus has advanced to a stage where the cornea is too thin, then treatment is not possible.
Corneal Cross Linking (CXL) has been shown to stop the progression of keratoconus in 90% of patients for approximately 7 years, As keratoconus tends not to progress later on in life, patients over 40 are generally not advised to have cross linking.
Options without Contact Lenses
When contact lenses cannot be tolerated and vision in glasses is reduced, Intra Corneal Ring Segments or ICRS (sometimes referred to as INTACS) may be an option.
Small, thin semi-circular rings are inserted into a small channel created within the cornea. The rings cause the cornea to flatten. They can be used to improve cone centration and lower astigmatism and myopia. After ICRS treatment many patients are able to better tolerate contact lenses and have improved vision in glasses.
Your inital consultation will involve collecting all the data about your eyes. Specifically this involves evaluating your vision, optical prescription, corneal topography, anterior segment OCT and thorough examination of the front of your eyes.
We will discuss your current issues and the options available to you in terms of vision correction and also the options for surgery. If you decide to try contact lenses, a keratoconus fitting appointment will be scheduled. As each patient has differing levels of keratoconus severity, the amount of time to fit lenses varies. In general, 2-3 appontments are required to achieve optimum fitting lenses.