What is Keratoconus?
Keratoconus is a progressive corneal disease that results in thinning and weakening of the cornea. Whilst it is relatiely common, occurring in about 1 in 2000 people in Australia, the exact cause is unknown, although the fact that many families have several members with keratoconus does imply a genetic link. Eye rubbing has also been linked to the development and progression of keratoconus.
Presenting most commonly during the teenage years as blurred vision, the condition tends to get progressively worse. Severity, rate and duration of progression vary greatly. As the cornea becomes thinner and weaker, its structure becomes unstable and astigmatism develops. Astigmatism occurs when the cornea is no longer perfectly round, and is effectively stronger in one direction than the other. The eye often also becomes more short sighted, or myopic, as keratoconus progresses. Astigmatism and Myopia account for the blurred vision in keratoconus. The natural course of the disease is for eventual stablisation of symptoms, although severity and age of stability is greatly variable.
What are the symptoms of keratoconus?
Usually both eyes are affected, although one eye may be much worse than the other. As astigmatism and myopia are both common conditions, diagnosis may be difficult in the early stages. It is often the progression of these findings that indicate the possibility of keratoconus. In addition, distorted vision, glare and light sensitivity may be present. Diagnosis will usually involve having detailed maps taken of your cornea, as well as a complete eye examination.
What is the management of keratoconus?
Avoidance of rubbing of the eye is imperative as the layers of collagen that make up the cornea may be joined to each other weakly, and may slide on each other with rubbing to result in further weakness. Eye drops may assist if there is itchiness of the eyes. Monitoring of disease progression is critical as a form of treatment, called corneal collagen cross-linking is very successful in in reducing the impact of this disease.
Dr Beltz will monitor for progression by taking corneal maps and measurements at each of your consultations, carefully comparing these to your previous results.
Corneal collagen cross-linking (CXL)
This treatment aims to stop the natural progression of keratoconus; prior to CXL there was no known way to achieve this. It does not reverse the condition. Whilst this treatment is relatively new, 5-year results have been reported and are overwhelmingly good. Long-term results are not yet known.
CXL surgery is performed as an outpatient day-surgery procedure. The patient will go home on the same day. Under local anaesthetic, the patient is awake but will not feel any pain nor be able to see the instruments. Riboflavin (vitamin B) drops are administered to the eye for 30 minutes after the outermost layer of the cornea (the epithelium) is removed. The epithelium will grow back after 2 – 3 days. A carefully calibrated and focused ultraviolet light is then applied to the cornea for 30 minutes. At the end of the procedure, a bandage contact lens is placed on the eye. Post-operatively, antibiotic and anti-inflammatory eye drops will be continued for two-weeks.. Given that the eye can be quite sore for a few days, one-week off work/school is recommended. Regular check ups ensure healing and monitor for stability.
Dr Beltz will consider if CXL is an appropriate option for your eyes. If so, she will explain this procedure in detail, including discussion of the risks and expected benefits. Given that CXL is relatively new and still in evolution, Dr Beltz regularly attends international discussions and meetings, and is well versed in new developments in this area. Feel free to discuss the latest developments with her at your consultation.
Initially, spectacles or soft contact lenses may be sufficient to correct the blurred vision caused by keratoconus. As the disease progresses hard contact lenses (rigid gas permeable contact lenses) are required to correct vision. They will be prescribed and fitted by your optometrist who will also help to guide you with the training and support required.
Certain patients may be eligible for a treatment called intra-corneal ring segments. These segments may be inserted into laser made self-sealing tracks in the cornea. As the rings flatten the steepened cornea, improved vision may result, allowing some patients to return to glasses use from previously requiring contact lenses.
If the above treatments do not yield an adequate level of vision, corneal transplantation may be required. Keratoconus is one of the most common indications for corneal transplantation in Australia, and has excellent results. Typically, transplants are either full thickness, or targeted towards replacing just the front layers of the cornea (anterior lamellar keratoplasty). Dr Beltz will be able to discuss the best options with you at your consultation.