Keratoconus

Risk Factors:

• History of Atopy (including asthma, eczema and hay fever)
• Patients with floppy eyelids
• Down Syndrome
• History of chronic eye rubbing

Symptoms of Keratoconus?

In early stages of the disease, patients will notice blurring of vision and will need increasingly frequent changes in spectacles for progressive astigmatism. In more progressive stages, good quality vision can only be obtained by wearing rigid contacts lenses and finally large scleral contact lenses. A key factor for progression of Keratoconus is persistent, habitual eye rubbing.

Rarely, a sudden painful reduction in vision heralds the onset of a hydrops event. It is caused by a rip on the delicate inner lining of the cornea and results in a deep corneal scar. Such an event usually limits the patient to full thickness graft surgery for the improvement in vision.

Treatment

There are several treatment paths to follow depending on the severity and progression of the disease. The can be split into medical treatments which attempt to stabilise the disease and refractive treatmetns which seek to improves the functional vision.

Surgical treatments

Corneal Cross Linking

This can slow and even cause some minor regression in the progression of Keratoconus. Clinicans remain reluctant to voice that it will halt the disease but one of the longest observed groups after cross linking from Dresden after one treatment resulted in relative stability throughout the group. This procedure utilizes Riboflavin and U.V. light to strengthen the patient’s cornea by cross linking components in the stroma. Objectively it improves vision by a line or two, but most patients appreciate no dicernable change in their vision.

Corneal Transplantation

 For moderate and advanced Keratoconus, where specialist contact lens fitting has failed, corneal transplantation has a place. This is a procedure where the disease cornea is removed and donor tissue is used to replace this tissue. Prior to corneal cross linking, Keratocnus patients presenting at the average age of diagnosis (23yrs) have a one in five chance of needing a corneal graft in their lifetime to aid their visual function. For patients presenting under age 17 years, their lifelong risk of needing a corneal graft is one in two! The corneal grafting rate for keratoconus as reported by the Australian corneal graft registry has dropped for the first time ever in 2015. As in other countries this has been attributed almost entirely due to the introduction of corneal cross-linking.

Refractive treatments

Spectacles

For most patients, their spectacles will have increasing levels of astigmatism correction as the condition progresses. Some of this will increasingly be irregular and thus the best correctable vision tends to drop.

Specialist Contact Lenses

For some individuals, increasingly frequent changes in spectacles may be required. Continued progression that results in poor spectacle corrected vision and this can only be corrected by wearing rigid contacts lenses. For mild to moderate disease small corneal RGP lenses work well. For more severe disease variations on scleral lenses provide comfortable good vision.

Optometrists who provide specialist contact lens fitting and follow up Keratoconus patients should be sought out to maximise non-surgical approaches to maintaining good quality vision in moderate Keratoconus.

Providing a refractive treatment without ensuring the medical disease is stabilised can last a long time. However refractive treatment alone will not last as long, will require extra re-fits and when the eye is no longer able to tolerate a contact lens is very likely to need a corneal transplant. Missing the opportunity to stabilise progressive keratoconus while prescribing rigid contact lens is becoming an increasingly indefensible position.