Keratoconus is an eye disease you don’t commonly hear about. In the early stages of the condition, you may find you can easily improve your vision with an update to your prescription. This may make it difficult to recognise or diagnose in the early days. However, as keratoconus progresses, it may become visually disabling to the point of requiring corneal surgery as the only way to improve your vision. To find out exactly what is keratoconus, keep reading.
What is Keratoconus?
Keratoconus is a disease of the cornea, the transparent dome at the front surface of your eye. It is characterised by progressive thinning of this tissue, which results in the weakened cornea bulging outwards due to the pressure exerted from the inside of the eyeball.
The name keratoconus comes from the cone-like shape of a cornea affected by this condition. A healthy cornea is more or less evenly rounded, like the curvature of half a soccer ball. In cases of astigmatism, a common type of refractive error, there may be some unequal curving of the cornea, but this is not to the extent of that found in keratoconus and is not progressive.
The cornea is the first surface through which light passes to form an image in the eye and brain. As this tissue thins and bulges outward through progressive keratoconus, your vision will become increasingly distorted. This results in a growing degree of astigmatism in your prescription.
Worldwide, keratoconus has a prevalence of roughly 1 in every 2000 people. In most cases, both eyes will have some degree of keratoconus present, though it is not uncommon for one eye to have more severe keratoconus compared to the other. This may result in one eye having more potential to improve vision through conservative treatment such as contact lenses, while the other eye may require corneal surgery.
How Do I Know if I Have Keratoconus?
Keratoconus is typically first diagnosed between 10 and 25 years old, however, some cases may go undetected for longer.
If you have a family history of keratoconus, you may be more attuned to its symptoms, leading you to seek the attention of an optometrist earlier. Otherwise, the symptoms of keratoconus in its early stages are not glaringly obvious to most people and may be dismissed as something else. You won’t be able to tell your cornea is bulging or distorted simply by looking in the mirror. Common symptoms include:
- Distorted or blurry vision. This is due to looking through a distorted cornea.
- Increasing glare sensitivity. As the light is coming into the eye is scattered through the uneven curvature of the cornea, we perceive this as glare. This may make certain activities, such as driving at night or reading backlit signs, particularly difficult and uncomfortable.
- Double vision. This may also look like ghosting, the presence of a faint second image next to the original image. The irregular curvature of the cornea is responsible for this.
- Increasing degrees of astigmatism. You may find your spectacle or contact lens prescription needs to be constantly updated, typically to accommodate more and more astigmatism.
In severe, advanced cases of keratoconus, the symptoms may be more debilitating. Legal blindness in one or both eyes as a result of keratoconus is not unknown. While keratoconus is not usually painful, in its late stages a condition called hydrops may develop. This occurs when the corneal tissue is so weakened that it’s subject to a sudden influx of fluid. Hydrops causes acute swelling of the cornea, accompanied by an abrupt drop in vision and pain.
Keratoconus is diagnosed with an eye care professional, such as an optometrist or ophthalmologist. He or she will use a number of tests to determine the diagnosis and monitor the progression of your condition. These tests include:
- Refraction. Refraction is the process of measuring the power of your eye, also known as its prescription. It may be done manually the traditional way, or nowadays, objectively with an auto-refractor. Recording your refraction over time can help to monitor the progression of keratoconus.
- Visual acuity. This is a measurement of how clearly you can see detail and will help form a decision of whether corneal surgery is indicated to improve your vision.
- Pachymetry. This is a measurement of the thickness of your cornea. Repeated measurements over time help to monitor progressive thinning.
- Corneal topography or keratometry. These tests provide a picture of the curvature of your cornea, identifying the extent of the bulging cone.
- Slit lamp. Your eye care professional views your cornea under a microscope to assess it for scarring and other signs of keratoconus.
What is Keratoconus Caused By?
The answer to “what is keratoconus caused by?” has still not been fully elucidated. It is thought there is a mix of genetics and environment. If you have a family member with keratoconus, you will carry a higher risk of experiencing the disease yourself. Other syndromes are associated with keratoconus, such as Down’s syndrome and Ehlers-Danlos syndrome.
Having a history of allergies is also considered a risk factor for the development of keratoconus. This may relate to an associated genetic predisposition to keratoconus, as well as a habit of rubbing the eyes.
Corneal Surgery for Keratoconus
In the mild to moderate stages, keratoconus may be managed with glasses or hard contact lenses. However, more advanced cases of keratoconus may require corneal grafting to improve the vision. This is performed by a corneal surgeon, who is an ophthalmologist who has specialised further in diseases of the cornea.
If you suspect that you or a family member may be developing keratoconus, or you need further information about what is keratoconus, contact your local optometrist.
Call us now on 03 9000 0389 for a consultation.
Note: Any surgical or invasive procedure carries risks. Before proceeding, you should seek a second opinion from an appropriately qualified health practitioner.