Keratoconus is one of the conditions I see most frequently in subspecialty corneal practice, and it is also one where treatment options have changed most dramatically over the past decade. Patients diagnosed with keratoconus today have access to a treatment pathway that can halt progression, maintain comfortable vision, and where necessary restore excellent vision through modern corneal transplantation, all with far better outcomes than were available even ten years ago.
What is keratoconus?
Keratoconus is a progressive condition in which the cornea gradually thins and bulges forward into an irregular cone shape. This distorts the way light enters the eye, causing blurred and distorted vision that often cannot be fully corrected with ordinary spectacle lenses. It typically begins in the teenage years or early twenties and may progress through the twenties and into the thirties.
The cause is not fully understood, but genetic factors, eye rubbing, and atopic conditions such as eczema, asthma, and hay fever are associated risk factors. Keratoconus is relatively common, affecting approximately one in two thousand people, though the true prevalence is likely higher given that mild cases are often underdiagnosed.
Step 1 — Early detection and monitoring
The most important step in keratoconus management is early detection. Corneal topography and tomography allow precise mapping of the corneal surface and detection of subclinical keratoconus before it causes significant visual symptoms. Optometrists routinely perform topography on patients with unexplained vision loss or unusual refractive changes, and this is the typical pathway to diagnosis.
Once diagnosed, the question is whether the keratoconus is stable or progressing. Progression is defined as a documented increase in the maximum keratometry reading of 1.0 dioptre or more over twelve months, or a decrease in minimum corneal thickness. Young patients, particularly those under 35, are at highest risk of progression and should be monitored at six-monthly intervals.
Step 2 — Corneal collagen cross-linking to halt progression
Corneal cross-linking is the only treatment that halts keratoconus progression. It works by creating new chemical bonds between collagen fibres in the corneal stroma, stiffening the tissue and preventing further thinning and bulging. Standard cross-linking involves removal of the surface cells, application of riboflavin drops for 30 minutes, followed by UV-A light exposure.
Cross-linking does not improve vision. It stabilises it. Most patients notice no change in their corrected vision after the procedure, which is the goal. The ideal candidate for cross-linking is a patient with documented progression and sufficient corneal thickness, generally above 400 microns. Cross-linking is highly effective, halting progression in approximately 90 to 95 per cent of appropriately selected patients.
Step 3 — Contact lenses and spectacle correction
Cross-linking addresses progression but does not correct the irregular astigmatism that keratoconus causes. For visual rehabilitation, rigid gas-permeable contact lenses remain the gold standard. They vault over the irregular corneal surface and provide a smooth optical interface, giving significantly better vision than spectacles in most keratoconus patients.
Scleral contact lenses, which rest on the white of the eye rather than the cornea, have become increasingly popular for keratoconus patients who find standard rigid lenses uncomfortable or difficult to fit. They are more comfortable and provide excellent optics.
Step 4 — Surgical options for advanced keratoconus
When contact lens tolerance is lost, or when corneal scarring has developed, corneal surgery options are considered. The two main surgical approaches for advanced keratoconus are Intacs and corneal transplantation.
Intacs are small plastic arc-shaped implants inserted into the corneal stroma. They flatten and regularise the cornea, potentially improving contact lens tolerance and in some patients spectacle-corrected vision. They are most useful in moderate keratoconus without significant scarring.
Deep anterior lamellar keratoplasty (DALK) is the corneal transplant of choice for advanced keratoconus. In DALK, the front layers of the cornea are replaced with donor tissue while the patient's own inner layer (Descemet membrane and endothelium) is preserved. Because the endothelium is not replaced, DALK carries a significantly lower rejection risk than full-thickness transplantation. Visual outcomes after DALK are excellent, with most patients achieving good corrected visual acuity. Recovery takes six to twelve months for full visual rehabilitation, but the lifetime of the graft is potentially much longer than full-thickness transplants because the patient's own endothelium is preserved.
For keratoconus patients in Melbourne's northern suburbs, I see initial assessments at Northern Eye Consultants in Bundoora. Cross-linking and DALK surgery are performed at Northpark Private Hospital. I also see patients at Bass Coast Eye Centre in Wonthaggi for those in the South Gippsland and Bass Coast region.
If you or your patient has been diagnosed with keratoconus and would like a subspecialty assessment, please contact Northern Eye Consultants on (03) 9466 8822 or refer via HealthLink EDI nthneyec.