About the types of keratoconus

The shape of the cornea as well as the location of where the cornea has thinned can determine the type of keratoconus.

There are four main types, in addition to rarer variations of the condition.

The type of keratoconus must be professionally diagnosed. This is usually done with the help of a special imaging device to map the surface contours of the eye.

The types of keratoconus

Round/nipple cone

Round or nipple cone keratoconus affects a relatively small area of the cornea, however the steepness of the affected area can be extreme. This keratoconus type results in marked visual deterioration.

Oval/sagging cone

Oval or sagging cone keratoconus affects a larger portion of the cornea. It can cause rupturing (or hydrops) of the cornea’s internal membranes and scarring, as well as making it harder to fit contact lenses.

Forme fruste

Forme fruste is the most common type of keratoconus. It is also the most mild. In fact, forme fruste keratoconus is usually symptom-free and only diagnosed by mapping the surface of the eye.

In forme fruste keratoconus the disease starts, but for some reason it stopped progressing. Most people with forme fruste keratoconus do not need treatment.

Keratoglobus

This is a rare type of keratoconus where the entire cornea thins and bulges forward. The best visual correction usually involves wearing large diameter scleral lenses.

Posterior keratoconus

Posterior keratoconus is a very rare condition where the inside surface of the cornea is abnormally thin, while the outside remains normal in curvature. It can be across the whole inner surface or in just one part. It tends to have less impact on vision because the outer surface of the cornea is unaffected.

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Mapping the cornea

Yellow and red regions show where the shape of the cornea is steeper.

Diagnosing keratoconus types

Optometrists diagnose the various types of keratoconus with specialised equipment. Some of these instruments are designed to map the topography of the cornea, while others measure the thickness of the cornea.

Corneal topography can be likened to the topography of hills and valleys. Cooler colours (blues) represent flatter areas, while warmer colours (orange and reds) indicate areas of steepening. Optometrists utilise corneal topography maps to assist in the diagnosing of specific types of corneal ectasia.

Furthermore, optometrists measure the thickness of the cornea using a global pachymeter. This instrument also aids in correctly diagnosing the type of keratoconus.

Managing keratoconus types

Each type of keratoconus requires expert management. Dr. Jim Kokkinakis is one of Australia’s foremost experts in the treatment and management of keratoconus.

Indeed, he is a keratoconus specialist and a Senior Lecturer at the UNSW School of Optometry.

If you suffer from keratoconus Dr. Kokkinakis can help offer guidance on how to effectively manage the condition, and provide valuable advice on the most suitable treatment options for your individual needs.