What is Keratoconus?
Keratoconus is a progressive eye disorder in which the normally round cornea gradually thins and bulges into a cone-like shape. This irregular shaped cornea causes aberrant bending of light, resulting in distorted vision. Keratoconus usually affects both eyes, however it is common for the degree of progression in each eye to be unequal, and for the condition to be significantly more advanced in one eye.
There are several treatment options for keratoconus, and this depends on the severity of the condition and whether your keratoconus is progressing. These include corneal cross-linking with or without laser resurfacing, corneal implants and corneal transplants. Dr Joanne Goh is a very experienced ophthalmologist and keratoconus specialist located in Melbourne who is highly skilled at performing these treatments.
Glasses and Contact Lenses
For mild keratoconus, glasses or soft contact lenses may be sufficient to provide good vision. In more advanced disease, special rigid contact lenses are usually required to correct for the irregular astigmatism. Dr Goh works closely with specialist keratoconus contact lens fitters and we can help arrange an appointment to have you fitted with the appropriate lenses for your eyes.
Corneal cross-linking (CXL)
If your keratoconus is progressing, a minor procedure called corneal cross-linking (CXL) may be required. Corneal cross-linking is a treatment that strengthens the cornea and stops keratoconus from getting worse. Treatment is recommended to patients whose keratoconus is getting worse as demonstrated by corneal curvature scans or a change in your spectacle prescription. Keratoconus corneal cross-linking is also recommended for patients with post-LASIK ectasia and pellucid marginal degeneration.
The cornea is made up of layers of collagen fibres that are held together by cross-links. Corneal cross-linking increases corneal rigidity by increasing the corneal collagen cross-links, thereby strengthening the cornea. During corneal cross-linking, the cornea is soaked in Vitamin B2 (riboflavin) drops before UV light is shone onto the cornea to activate the riboflavin. This photochemical reaction strengthens the cross-links between collagen fibres in the cornea. Studies have shown that cross-linking increases corneal strength by up to 300% and is successful in stopping progression of keratoconus in over 90% of patients. In some patients, flattening of the cornea and an improvement in unaided visual acuity also occurs.
It is important to understand that corneal cross-linking is not a cure for keratoconus. For most people, this treatment stops the progression and stabilises the condition. You will still need to wear your glasses or contact lenses after surgery, although the prescription may change.
Corneal laser resurfacing combined with cross-linking
(Laser refractive CXL)
In laser refractive CXL, a defined amount of custom laser treatment is performed to re-shape your cornea, which is then locked in with CXL to preserve this new shape. This treatment aims to improve the overall shape of your cornea as well as stop the progression of your keratoconus. This results in sharper vision, often accompanied by a reduced prescription in your glasses or contact lenses. If you have very mild keratoconus, this treatment may even improve your vision sufficiently to reduce your dependence on glasses or contact lenses.
This is a relatively new treatment that has shown impressive results in a select group of patients who meet the strict treatment criteria. The amount of re-shaping that can be achieved will depend on your initial corneal thickness which will be assessed at your consultation.
Kerarings, also known as intracorneal rings, are transparent, semi-circular custom-made rings that are implanted into the peripheral cornea. They flatten the peak of the cone and therefore regularises the shape of your distorted cornea. This procedure can be combined with laser refractive CXL to further improve the shape and achieve stabilisation of the cornea.
Suitable candidates are usually those who are unable to achieve a good level of vision with glasses or are unable to tolerate contact lenses. Kerarings can improve your vision sufficiently such that glasses and/or contact lenses are easier to tolerate.
This procedure is performed under topical anaesthetic (numbing eye drops). A femtosecond laser is used to create the tunnel in the cornea where the Keraring is placed. The Keraring is then inserted into the tunnel and dialed into a precise, pre-determined location.
This procedure is easily reversible. The rings can be removed at any time, and the cornea reverts back to its original shape.
Implantable collamer lenses (ICLs)
Implantable collamer lenses (ICLs) are thin, clear prescription lenses that are surgically implanted into the eye, behind the pupil and in front of your natural lens. ICLs are suitable for select patients with good spectacle corrected vision but have prescriptions that are too high to tolerate. ICLs can also be implanted in patients whose keratoconus is stable and who are keen to reduce their dependence on glasses or contact lenses.
Corneal transplantation is offered in severe keratoconus where other options have failed or are not suitable.
In keratoconus, only the outer two layers of the affected cornea are replaced, preserving the inner layer of the cornea where possible. This technique, known as deep anterior lamellar keratoplasty (DALK), reduces the surgical risks and significantly improves the success rate of the transplant.