The management of keratoconus needs to shift from the current approach of late-stage intervention when disease has progressed significantly and keratoplasty is required to a more prophylactic form of early intervention to ensure that few, if any, patients ever actually require surgery, says Michael W. Belin MD, Professor of Ophthalmology & Vision Science at
the University of Arizona, Tucson, Arizona, USA.
“Few, if any, keratoconus patients should ever reach the stage where they require keratoplasty. If we look at penetrating keratoplasty (PK) and deep anterior lamellar keratoplasty (DALK) and intracorneal rings, they really all represent a management failure, not a success. The biggest limitation to date is a failure to diagnose at an earlier stage and prevent progression,” he told delegates attending the European Society of Ophthalmology (SOE) meeting in Nice, France.
Looking at current therapeutic approaches to keratoconus, Dr Belin said that contact lenses are a double-edged sword.
“Soft contact lenses are rarely effective, while PMMA and rigid gas permeable lenses greatly improve vision but can cause scarring and also mask disease progression. We see this too often. A patient is referred to an optometrist, they are fitted with rigid lenses, they see well, the disease progresses and by the time they get referred back to us for other treatment we are at the end stage disease, which requires DALK or PK,” he said.
Another option is the use of scleral lenses, which can treat advanced disease not amenable to other lenses, said Dr Belin. “They are very effective and can treat a vast array of pathologic conditions on the cornea. The best known is the Boston scleral lens, but at the moment only a limited number of centres can fit the lenses. It can be challenging to fit and the lenses are expensive,” he said. The fundamental problem with scleral lenses, however, is that fitting them means the disease has already progressed to the point of irreversible vision loss, said Dr Belin.
“All patients requiring rigid lenses had early progressive disease at some point so we failed to diagnose disease at an earlier stage. And the reason for that is that lens fitters tend to hold on to patients for too long for financial reasons. They are not ophthalmologists or surgeons and they tend to refer patients way too late,” he said.
Dr Belin said that it is important to try to prevent eye rubbing and to treat possible causes of it in keratoconus patients.
“We don’t know at this stage if there is a direct cause and effect between eye rubbing and keratoconus. Some have concluded that because atopic disease and keratoconus appear coincidentally that there must be a cause and effect relationship. But that does not necessarily imply causation or an aetiology – they may simply be linked,” he said.
Nevertheless, there is sufficient anecdotal data to recommend cessation of eye rubbing or modification of the pressure point, said Dr Belin.
“You often have to enlist the help of family members. We need to treat atopic disease and allergic disorders with topical or systemic agents, and often we refer patients to an allergy specialist for desensitisation, which may be helpful,” he said.
In terms of cross-linking (CXL) intervention, Dr Belin said it was high time for a rethink on the subject.
“We don’t treat high blood pressure after the patient’s first stroke, or diabetes only after an episode of ketoacidosis or high cholesterol after the first myocardial infarction, so why do we wait to treat keratoconus only after the patient loses vision?” he asked.
In Dr Belin’s view the “holy grail” should be the earliest possible identification and treatment of progressive disease with a high safety profile, with the goal of preserving or preventing vision loss instead of limiting the damage after the fact.
“The concept of early intervention with CXL at a young age is not new. Back in 2009, the pioneers of CXL said that early treatment would be more efficacious and limit some of the adverse effects,” he concluded.
Michael W. Belin: firstname.lastname@example.org