Keratoconus Treatments

WHAT IS KERATOCONUS?

Keratoconus is a degenerative condition of the cornea characterised by progressive bulging and thinning. Patients are often first detected when their glasses prescription is getting stronger with a more irregular shape.

WHO GETS KERATOCONUS?

Keratoconus is often picked up in teenagers or young adults. There is usually a background of eye rubbing which is the greatest risk factor for development and progression of keratoconus. Patients with allergic eye problems are more likely to get keratoconus due to the eye rubbing as are certain racial groups such as Pacific Islanders.

Keratoconus is surprisingly common. Previously it was thought the disease only affected around 1 in 2000 Australians, but a screening study in 2020 found 1 out of 84 twenty year olds was affected in Western Australia (1). Men and women seem to be equally affected. In the majority of cases it becomes apparent between the ages of 16 and 35. After this time progression often slows or stops. It is usually in both eyes though often is worse in one eye.

WHAT CAUSES KERATOCONUS?

The cause of keratoconus remains poorly understood and there are likely genetic and environmental factors. One in ten patients have an affected relative. Eye rubbing is known to be an important factor and you should avoid this as much as possible.

IF LEFT UNTREATED, CAN KERATOCONUS CAUSE BLINDNESS?

Keratoconus does not lead to complete loss of vision, though untreated and if advanced it can lead to severe visual loss enough for patients to be classified as legally blind. With early detection and treatment however, patients generally do very well and their vision can be preserved.

HOW IS KERATOCONUS TREATED?

The two main issues in the treatment of keratoconus are preventing the condition from getting worse and also improving vision.

If the keratoconus is worsening, corneal collagen cross-linking is the procedure of choice. This procedure uses riboflavin and ultraviolet light to stiffen the cornea and prevent worsening vision. This can be combined with a laser procedure to help improve your vision at the same time.

Improvement of vision may initially be with glasses alone in mild keratoconus. In worse disease the shape of the cornea becomes steeper and more irregular and glasses no longer help. Rigid contact lenses can help restore vision at this point as they vault over the cornea cancelling its optical effects out. If contact lenses are not comfortable or are no longer helping, a surgical procedure can be used to improve the corneal shape and therefor vision.

1. Laser regularisation of the cornea

   Phototherapeutic keratectomy or “PTK” is a laser treatment that reshapes the cornea by removing tissue at the steepest parts. This is a highly customisable treatment with a high degree of control over the shape of the cornea. It can be done at the same time or after cross linking. Read more about laser for keratoconus.

2. Corneal ring segments

   In more advanced keratoconus the cornea has a very poor cone shape. Laser regularisation with PTK would need to remove too much tissue to make a useful difference which would weaken the cornea and reduce safety. At this point, implantation of 1 or 2 plastic support rings into the cornea can be performed to improve the shape - this is called intracorneal ring segments or ICRS. The benefit of this procedure is the creation of a large improvement of shape without removal of any tissue. The outcome is less predictable than with laser and most patients will need a PTK laser refinement 3-6 months after the ring segments have been placed to enhance the result. The newest evolution of this treatment is to implant human donor corneal tissue instead of a plastic ring which has a significant number of benefits. This is called Corneal Allogenic Intrastromal Ring Segments or “CAIRS”. In May 2021, Dr Gunn introduced this procedure to the region as the first surgeon to perform CAIRS in Australia / NZ. Read more about the CAIRS procedure.

3. Full corneal transplant

   If the cornea is scarred or vision cannot be improved with previous measures, a full or 98% thickness corneal transplant is required to improve vision. This is the most invasive procedure but in the most severe disease is the only option. Read more about corneal transplantation.

There is no “one size fits all” approach in keratoconus. Previously, the full corneal transplant was the only option once contact lenses were no longer tolerated, but advances in technology have provided a toolbox of less invasive corneal procedures. For each patient the treatment plan is customised to the severity and of their disease. Multiple steps are often required to obtain excellent outcomes - often waiting 3-12 months between steps to wait for the cornea to stabilise. The worst eye is usually treated first until it is at least equal or better than the fellow eye.