Keratoconus

Diagnosis

Diagnosing keratoconus involves reviewing medical and family history and conducting a detailed eye examination. Additional tests help evaluate the shape and thickness of the cornea to confirm early or advanced signs of the condition.

Tests used to diagnose keratoconus include:

• Eye refraction to measure visual clarity using equipment such as a phoropter or a handheld retinoscope.

• Slit-lamp examination to inspect the cornea, its shape and any other eye problems using a focused beam of light and a low-powered microscope.

• Keratometry to measure corneal curvature by analyzing how light reflects off the cornea.

• Computerized corneal mapping using tests such as corneal tomography and corneal topography. These create detailed images of the cornea’s shape and can detect early keratoconus, even when slit-lamp findings appear normal.

Treatment

Treatment depends on the severity of keratoconus and how quickly it is progressing. The two main goals are stabilizing the cornea and improving vision.

If the condition is getting worse, corneal collagen cross-linking may be recommended. This procedure strengthens the cornea and may reduce bulging, helping glasses or contact lenses work more effectively. It may also reduce the likelihood of needing a cornea transplant later.

Vision improvement strategies depend on the stage of keratoconus. Mild to moderate cases often respond well to eyeglasses or contact lenses and may remain long-term solutions if the cornea becomes stable naturally or after cross-linking.

In advanced cases, the cornea may become scarred or contact lenses may no longer fit comfortably. In such situations, a cornea transplant may be necessary.

Lenses

Different types of lenses are used depending on corneal shape changes and the level of vision distortion.

• Eyeglasses or soft contact lenses for early keratoconus to correct blurry or distorted vision. Frequent prescription changes may be needed.

• Hard contact lenses, including rigid gas-permeable types, for more advanced cases. These may feel uncomfortable initially but often provide excellent vision once adjusted.

• Piggyback lenses, where a rigid lens is placed on top of a soft lens to improve comfort.

• Hybrid lenses with a rigid center and a soft outer ring for people who cannot tolerate standard hard lenses.

• Scleral lenses for significantly irregular corneas. These lenses rest on the sclera rather than the cornea, arching over the cornea without touching it.

Fitting rigid or scleral lenses requires an experienced eye doctor. Regular checkups are important, as ill-fitting lenses can damage the cornea.

Therapies

Corneal cross-linking involves applying riboflavin eye drops to the cornea and exposing it to ultraviolet light. This strengthens the corneal structure and helps prevent further progression of keratoconus. Early treatment may reduce the risk of vision loss by stabilizing the cornea.

Surgery

Surgery may be required when keratoconus leads to corneal scarring, extreme thinning, poor vision even with strong prescription lenses or when contact lenses become intolerable.

Surgical options include:

• Intrastromal corneal ring segments for mild to moderate keratoconus. These synthetic rings are inserted into the cornea to flatten it, improve vision and help contact lenses fit better. This procedure may be combined with corneal cross-linking.

• Cornea transplant when scarring or thinning is severe. Depending on the condition, all or part of the cornea may be replaced with healthy donor tissue in a procedure called keratoplasty.

Cornea transplants for keratoconus are generally very successful. Possible complications include graft rejection, infection, astigmatism and poor vision. Astigmatism after surgery may be managed with hard contact lenses, which often feel more comfortable after a transplant.