Keratoconus is an eye disease characterized by the thinning and conical deformation of the cornea. It occurs in young adults and can lead to visual impairment. The treatment method used to halt the progression of keratoconus is called Cross-Linking. This procedure aims to strengthen the corneal structure and is aimed at stopping the progression of the disease. This method is generally applied to enhance the visual quality of patients with keratoconus and to prevent more serious complications.
What is Keratoconus?
Keratoconus is a progressive eye disease that occurs with the thinning and forward coning of the cornea, the transparent layer at the front of the eye.
A healthy cornea allows light to refract properly onto the retina. However, in patients with keratoconus, the corneal structure deteriorates, causing light to not fall correctly on the retina, resulting in blurred, wavy, or distorted vision.
This disease often begins during adolescence and may show slow progression in the 20s. If not detected early, the thinning of the cornea may increase, leading to permanent vision loss. Keratoconus typically affects both eyes, although one eye may be at a more advanced stage than the other.
What are the Symptoms of Keratoconus?
Keratoconus can initially be mistaken for vision problems that can be corrected with glasses. Symptoms develop due to the deformation and thinning of the cornea:
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Frequent changes in prescription glasses
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Inability to see clearly with glasses
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Noticed at night: light scattering, glare, and halos
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Light sensitivity and eye discomfort
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Blurred or double vision
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Experiencing allergies or itching in the eyes
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Discomfort due to the habit of rubbing eyes
What are the Causes of Keratoconus?
The causes of keratoconus can include genetic predisposition, eye trauma, incorrect contact lens usage, and systemic diseases.
- Genetic Factors
Individuals with a family history of keratoconus are at higher risk for developing this disease. Some genetic diseases that cause connective tissue weakness can affect the cornea.
- Eye Rubbing Habit
Rubbing the eyes is a significant environmental risk factor for keratoconus. Frequent rubbing by individuals with allergic tendencies can lead to microscopic trauma in the cornea, gradually weakening its structure. In the long term, this can cause the cornea to take on a conical shape.
- Allergic Eye Diseases
Diseases like allergic conjunctivitis can cause itching in the eyes and promote rubbing behavior. Therefore, it is essential for individuals with allergies to protect their eye health with appropriate treatments.
- Hormonal Factors
Biochemical changes in eye tissues during puberty, pregnancy, or hormonal changes can affect the cornea's resilience. Long-term contact lens use may also place mechanical stress on the corneal surface.
How is Keratoconus Diagnosed?
The diagnosis of keratoconus is made through a detailed eye examination together with corneal topography or corneal tomography. Imaging techniques provide a detailed analysis of corneal thickness, curvature, and surface shape.
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Vision test: This evaluates how effective the patient's vision is with glasses or lenses.
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Corneal topography: A map of the corneal surface is created to identify deformations.
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Pachymetry test: Measures the thickness of the cornea.
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Biomicroscopy: Detailed examination of corneal structure through eye examination.
How is Keratoconus Treated?
Treatment for keratoconus is planned according to the disease stage and the corneal structure. The aim is to halt progression and preserve existing visual levels.
Early Stage Treatment
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Vision can be supported by using glasses or contact lenses.
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Cross-Linking (Corneal Strengthening) can be applied to halt progression.
Advanced Stage Treatment
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Due to structural degradation of the cornea, specially designed rigid or hybrid contact lenses may be preferred.
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In some patients, corneal rings (Intacs) may be needed to enhance visual acuity.
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In advanced stages, if corneal transparency is lost or severe deformation occurs, corneal transplantation may be performed.
What is Cross-Linking (Corneal Strengthening)?
The Cross-Linking treatment applied in keratoconus aims to increase the structural resilience of the cornea. In this treatment, using riboflavin and UV-A light, new bonds are formed between collagen fibers in the cornea, thereby increasing the robustness of corneal tissue and potentially slowing disease progression.
How is the Cross-Linking Procedure Performed?
Keratoconus is a progressive eye condition that causes the cornea to take a cone shape. This disorder can significantly reduce visual quality.
When corneal thinning becomes pronounced and the disease actively progresses, the Cross-Linking (corneal cross-linking) treatment is recommended. This procedure, performed in the early stages, can help slow the course of the disease and prevent vision loss.
Cross-Linking is generally evaluated for the following patient groups:
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Individuals who exhibit changes in corneal maps or eyeglass prescriptions may be considered for Cross-Linking treatment to halt progression.
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Due to the early onset of keratoconus and rapid progression in this period, adolescents and individuals in their 20s with identified corneal thinning are prioritized in terms of treatment evaluation.
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Strengthening the corneal structure may be considered in those experiencing decreased visual quality or who cannot achieve sufficient clarity with current optical corrections.
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Individuals with corneas above a certain thickness and no obstructive conditions such as infections or inflammation are evaluated as suitable candidates for the procedure.
Frequently Asked Questions
Can keratoconus be treated?
Keratoconus is a progressive disease causing permanent changes in the corneal structure. It cannot be completely eliminated but its progression can be slowed or halted with early diagnosis and appropriate treatment methods.
How is Cross-Linking surgery performed?
Cross-Linking is not a surgery in the classical sense. It is a corneal strengthening procedure performed without incision, using drop anesthesia. Riboflavin (vitamin B2) and UVA light are used during the procedure.
How long does a Cross-Linking treatment take?
It is a treatment lasting approximately 30–45 minutes. After riboflavin is applied to the eye surface, controlled UVA light is used. Post-treatment, the patient can resume daily activities.
Is the use of glasses or lenses required after Cross-Linking?
Yes, while the Cross-Linking procedure halts disease progression, it does not correct existing visual defects. Glasses or special contact lenses may be used for visual acuity.