Keratoconus - Corneal Diseases

Eye health is one of the most important factors that directly affects quality of life. The proper functioning of vision depends on the healthy operation of all structures and layers of the eye. Among these structures, the cornea, located at the very front and outermost part of the eye, plays a vital role by allowing light to enter and by helping form clear images. Any deterioration of this transparent structure can lead to a variety of vision problems. Keratoconus and other corneal diseases, in particular, can cause serious limitations in daily life. In this article, as emphasized by Op. Dr. Diclehan, we will examine in detail the causes, symptoms, and the most up-to-date treatment methods for vision problems originating from the cornea.

What Is the Cornea and What Is Its Function?

Structure of the Cornea
The cornea is the outermost layer of the eye, and with its transparent structure, it helps bend (refract) light so that it focuses on the retina. This is also the area where corrective tools like eyeglasses or contact lenses exert their effect. The cornea consists of five main layers: the epithelium, Bowman’s layer, stroma, Descemet’s membrane, and the endothelium.

The cornea not only provides mechanical protection but also accounts for about 70% of the eye's total refractive power. For this reason, any structural deterioration in the cornea can severely reduce vision quality.

Why Is Corneal Health Important?

Because of its transparency, the cornea allows light to pass through without obstruction. However, trauma, infection, genetic predisposition, or metabolic disorders can compromise its structure. When this happens, symptoms such as blurry vision, light sensitivity, and severe vision loss may occur. Among these, keratoconus is one of the most common corneal diseases that causes significant deformation of the corneal structure.

What Is Keratoconus?

Keratoconus is a progressive eye disease characterized by thinning of the cornea and its forward bulging into a cone shape. This condition disrupts the refractive power of the eye, causing irregular astigmatism and myopia. It usually affects both eyes but can progress asymmetrically.

Keratoconus often begins during adolescence and may progress into the 30s. With early diagnosis and proper intervention, vision loss can largely be prevented.

Prevalence of Keratoconus

It is estimated to affect about 1 in every 2,000 people, though with advanced diagnostic technologies, the actual rate may be higher. Individuals with a family history of keratoconus or those who habitually rub their eyes are at greater risk.

Op. Dr. Diclehan emphasizes that early detection of keratoconus patients is critical for treatment success and for preventing vision loss.

Causes of Keratoconus

• Genetic Factors: Individuals with a family history of keratoconus are at higher risk, indicating a strong genetic component.
• Eye Rubbing: Frequent eye rubbing, particularly in individuals with allergies, weakens the corneal structure and accelerates disease progression.
• Allergic Conditions: Conditions like atopic dermatitis or hay fever can make the cornea more vulnerable, triggering or worsening keratoconus.
• Enzymatic Imbalances: Research suggests that certain enzyme deficiencies in corneal tissue may lead to structural weakness.

Symptoms of Keratoconus

• Blurred or distorted vision
• Seeing halos around lights
• Inability to achieve clear vision with glasses
• Eye strain or fatigue
• Increased difficulty seeing at night
• Frequent changes in eyeglass prescription

Detecting these symptoms, especially at a young age, makes it possible to control the disease in its early stages.

Common Corneal Diseases

Corneal diseases are not limited to keratoconus. The cornea can also be affected by infections, trauma, autoimmune diseases, and degenerative conditions. Some of the most common include:

• Infectious Keratitis: Caused by bacteria, viruses, fungi, or parasites; presents with redness, pain, discharge, and vision loss; requires urgent treatment.
• Corneal Ulcer: A perforation of the corneal surface due to infection or trauma; carries a high risk of vision loss.
• Fuchs’ Endothelial Dystrophy: Dysfunction of endothelial cells leading to corneal swelling; advanced cases may require corneal transplantation.
• Herpes Simplex Keratitis: Recurring corneal infections caused by the herpes virus, often leaving scarring that severely impairs vision.
• Corneal Scarring: Opacities from trauma, surgery, burns, or infections that disrupt corneal clarity and vision.
• Dystrophies: A group of genetically inherited conditions affecting different layers of the cornea, causing cloudy or blurred vision.

Diagnosis of Keratoconus

Diagnosis starts with assessing visual acuity and prescription. If good vision cannot be achieved with glasses, more advanced tests are performed

• Keratometry: Measures corneal curvature and can detect early keratoconus.
• Topography / Tomography: Creates a corneal map, providing detailed information on thickness, curvature, and symmetry — the gold standard in keratoconus diagnosis.
• Pachymetry: Measures corneal thickness, which is significantly reduced in keratoconus patients.

Op. Dr. Diclehan notes that advanced imaging technologies have made early detection of keratoconus much easier and more accurate.

Treatment Options for Keratoconus and Corneal Diseases

• Glasses and Soft Contact Lenses: Useful in early stages but become inadequate as the disease progresses.
• Rigid Gas Permeable (RGP) Lenses: Provide sharper vision by creating a smoother refractive surface.
• Hybrid and Scleral Lenses: Combine comfort and stability; preferred in advanced keratoconus cases.
• Corneal Cross-Linking (CXL): A modern treatment that strengthens corneal structure using riboflavin drops and UV light to halt disease progression.
• Intrastromal Ring Segments (Intacs): Small plastic rings implanted in the cornea to flatten its shape and improve vision.
• Corneal Transplant (Keratoplasty): Reserved for advanced keratoconus or severe corneal diseases; can be performed as full-thickness (PK) or partial-thickness (DALK) transplantation. Although highly successful, lifelong monitoring is required.

Op. Dr. Diclehan emphasizes that customized treatment plans based on disease stage are key to preserving vision.

Protecting Corneal Health

• Avoid rubbing your eyes
• Manage allergies effectively
• Maintain strict hygiene to prevent corneal infections
• Protect eyes from trauma
• Clean and replace contact lenses regularly
• Have annual eye exams

Individuals with a family history of keratoconus should undergo early screening.

Keratoconus and Diabetes

Some studies suggest that individuals with diabetes may have thicker corneas, potentially lowering the risk of keratoconus, though this finding is not yet conclusive. Nonetheless, the impact of systemic diseases like diabetes on corneal health should not be overlooked.

Diabetic retinopathy, a complication of diabetes, is another serious condition that can cause vision loss, highlighting the importance of regular eye examinations in systemic illnesses.

The cornea, often described as the transparent shield of the eye, is the foundation of clear vision. Keratoconus and other corneal diseases, if not diagnosed in time, can lead to severe vision problems. However, with early detection, regular monitoring, and advanced treatment technologies, these diseases can often be effectively managed.

Op. Dr. Diclehan emphasizes that early diagnosis, personalized patient follow-up, and tailored treatment strategies are indispensable for protecting eye health. Especially in young individuals experiencing frequent eye rubbing or fluctuating vision, consulting an eye specialist without delay is crucial.