Keratoconus – Irregular Astigmatism
Keratoconus is a disease of the cornea, the transparent, dome-shaped layer at the front of the eye. The cornea is normally a regular lens that focuses light onto the retina. In keratoconus, it bulges, becoming thinner and protruding forward. This is known as irregular astigmatism . The corneal deformation makes the projection of light rays irregular, resulting in blurred vision. Keratoconus is a progressive disease, most often appearing during adolescence in patients who compulsively rub their eyes. Treatment involves stopping eye rubbing, corrective lenses such as glasses or rigid contact lenses, and sometimes surgery.
What is keratoconus?
Keratoconus is an irregular deformation of the cornea, resulting in astigmatism that is more pronounced at the bottom of the eye than at the top.
The cornea thins and forms a downward bulge. This is called irregular astigmatism.
The disease usually appears during adolescence and progresses gradually.
Vision is uncomfortable with glasses, but can be corrected with rigid contact lenses.
What are the causes of keratoconus?
Keratoconus usually results from a combination of risk factors. The clearly identified factors are:
Heredity – 1/10 affected patient also has an affected family member.
Atopy – Eye allergies are a frequently found predisposing factor.
Excessive rubbing of the eyes, aggravating the deformation
Genetics – Connective tissue fragility such as Marfan syndrome, trisomy 21 and Ehlers-Danlos.
Symptoms
Keratoconus is a slowly progressive disease. Visual symptoms gradually worsen during adolescence and early adulthood. Both eyes are often affected asymmetrically.
In the early stages, symptoms may include:
A slight visual blur
A slightly distorted view – straight lines appear curved or wavy
Photophobia – Increased sensitivity to light and glare
In advanced stages, the symptoms of keratoconus are:
A constantly blurred and distorted vision.
Progressive myopia and astigmatism
Therefore, you may often need new prescriptions for your glasses.
Keratoconus typically takes years to progress from the early to the advanced stage.
Diagnosis
Keratoconus can be diagnosed during a routine eye exam. Your ophthalmologist will examine your cornea and may measure its curvature (keratometry). This allows them to detect any changes in its shape.
The examination is completed by topography. The device performs a 3D reconstruction of the cornea, allowing for the detection and monitoring of keratoconus.
Treatment
The primary risk factor for keratoconus is compulsive eye rubbing.
Therefore, all eye rubbing must be stopped.
To help you, your ophthalmologist will prescribe soothing moisturizing eye drops (washes and artificial tears), as well as an anti-allergy treatment.
The visual treatment for keratoconus then depends on your symptoms:
If your symptoms are mild, your vision can be corrected with glasses.
If you are dissatisfied with the glasses, you will need to have a rigid lens fitting done to correct the astigmatism.
In cases of contact lens intolerance or advanced keratoconus, surgical treatments are available:
Cross-linking (CXL) – This is a UV light treatment designed to strengthen the cornea. This can slow down, or even stop, the progression of keratoconus.
Intracorneal rings – These are small arc-shaped implants that serve as “reinforcing beams” to flatten the cornea and eliminate astigmatism.
Corneal transplantation – When the cornea has become too thin, your ophthalmologist replaces all or part of its thickness with a cornea from a healthy donor.
Topo-guided photokeratectomy – Sometimes the most curved part of the cornea can be flattened with a laser. However
Complications
Hydrops is a sudden worsening of keratoconus. The cornea thins abruptly, forming a small bubble that can perforate.
The disease causes a sudden loss of vision and a debilitating scar during the healing process. A corneal transplant is frequently necessary.
Frequently Asked Questions
Is keratoconus serious?
Yes and no, there are different degrees of keratoconus and therefore different levels of severity.
For example, keratoconus discovered in adolescence following a decrease in vision is serious.
A mild case of keratoconus discovered at age 35 during a refractive surgery assessment is not serious.
How to treat keratoconus?
The first treatment for keratoconus is to stop rubbing your eyes! Other treatments exist for:
Stabilizing keratoconus: Cross-linking
Improving vision – Ring, PKT, corneal transplant
What is irregular astigmatism?
Irregular astigmatism is astigmatism that does not have the same power between the top and bottom of the eye. This is the case with keratoconus, where the cornea is more curved (astigmatic) in its lower part.