Keratoconus: Symptoms, Causes, and Treatment

What is Keratoconus?

Keratoconus is a progressive eye condition where the normally round cornea thins and begins to bulge into a cone-like shape. This distortion affects your vision, causing blurriness, distortion, and increased sensitivity to light. The cornea is the clear, dome-shaped front surface of your eye, and its shape is crucial for focusing light properly onto the retina. When the cornea's structure weakens, it cannot maintain its round shape, leading to visual impairments.

Keratoconus typically begins in the teenage years or early 20s and progresses slowly over a decade or more. It usually affects both eyes, though one eye may be more severely affected than the other. According to the National Eye Institute (NEI), keratoconus affects approximately 1 in 2,000 people, though some studies suggest it may be more common.

Common Causes

The exact cause of keratoconus is not fully understood, but several factors are believed to contribute to its development. These include:

• Genetic Predisposition: Keratoconus often runs in families. If you have a family member with the condition, your risk of developing it increases.
• Eye Rubbing: Chronic and vigorous eye rubbing can weaken the cornea over time, contributing to the progression of keratoconus.
• Allergies: Conditions like hay fever, asthma, and eczema are associated with frequent eye rubbing, which may increase the risk.
• Oxydative Stress: An imbalance between antioxidants and free radicals in the cornea can lead to weakening of the corneal tissue.
• Ultraviolet (UV) Exposure: Prolonged exposure to UV rays from the sun or tanning beds may contribute to corneal damage.
• Poorly Fitted Contact Lenses: Ill-fitting contact lenses can cause chronic irritation and rubbing, potentially leading to corneal thinning.
• Connective Tissue Disorders: Conditions like Marfan syndrome, Ehlers-Danlos syndrome, and osteogenesis imperfecta are linked to a higher risk of keratoconus.
• Down Syndrome: Individuals with Down syndrome have a higher prevalence of keratoconus.
• Hormonal Changes: Some studies suggest that hormonal fluctuations, such as those during pregnancy, may influence the progression of keratoconus.
• Chronic Eye Inflammation: Conditions like vernal keratoconjunctivitis (a type of allergic eye inflammation) can increase the risk.

While these factors are associated with keratoconus, the condition can also develop without any obvious cause. Research is ongoing to better understand the underlying mechanisms.

Associated Symptoms

Keratoconus can cause a variety of symptoms that affect vision and eye comfort. These symptoms often worsen over time and may include:

• Blurred or Distorted Vision: This is often the first sign. Straight lines may appear wavy or bent, and vision may become increasingly blurry.
• Increased Sensitivity to Light: Known as photophobia, this can make bright lights uncomfortable or painful.
• Glare and Halos: You may see halos around lights, especially at night, which can make driving difficult.
• Frequent Changes in Eyeglass Prescription: As the cornea changes shape, your vision prescription may need frequent updates.
• Sudden Worsening or Clouding of Vision: This can occur if the cornea swells suddenly, a condition known as corneal hydrops.
• Eye Redness or Swelling: The eyes may become irritated, red, or swollen, especially if you rub them frequently.
• Double Vision: Also known as diplopia, this can occur in one or both eyes.
• Poor Night Vision: Difficulty seeing in low-light conditions is common as the condition progresses.

These symptoms can vary widely from person to person. Some individuals may experience mild symptoms that stabilize over time, while others may have severe and progressive vision loss.

When to See a Doctor

It’s important to see an eye care professional if you experience any of the following:

• Sudden or rapid worsening of vision in one or both eyes.
• Increased blurriness or distortion that isn’t corrected with your current glasses or contact lenses.
• Frequent changes in your eyeglass or contact lens prescription.
• Persistent eye pain, redness, or swelling.
• Seeing halos around lights or increased sensitivity to light.
• Difficulty driving at night due to glare or poor vision.

Early diagnosis and treatment are key to managing keratoconus effectively. If you have a family history of keratoconus or any of the associated risk factors, regular eye exams are especially important.

Diagnosis

Diagnosing keratoconus typically involves a comprehensive eye examination. Your eye doctor may use several tests to assess the shape and health of your cornea:

• Slit-Lamp Examination: This microscope-like device allows the doctor to examine the cornea in detail, looking for signs of thinning or irregularities.
• Corneal Topography: This test creates a detailed map of the cornea’s surface, highlighting any abnormalities in its shape. It’s one of the most common tools for diagnosing keratoconus.
• Pachymetry: This measures the thickness of the cornea. Thinning of the cornea is a key indicator of keratoconus.
• Wavefront Aberrometry: This test measures how light travels through the eye, identifying distortions caused by an irregular cornea.
• Retinal Examination: The doctor may also examine the retina to rule out other conditions that could be causing your symptoms.

In some cases, your doctor may refer you to a corneal specialist for further evaluation, especially if the condition is advanced or if you’re considering surgical options.

Treatment Options

The treatment for keratoconus depends on the severity of the condition and how quickly it’s progressing. Options range from corrective lenses to surgical interventions:

Non-Surgical Treatments

• Glasses or Soft Contact Lenses: In the early stages, vision can often be corrected with glasses or soft contact lenses. However, as the condition progresses, these may no longer provide adequate correction.
• Rigid Gas Permeable (RGP) Contact Lenses: These lenses are often prescribed for moderate keratoconus. They provide a smooth, uniform surface to help correct vision by masking the irregular shape of the cornea.
• Hybrid Contact Lenses: These lenses combine a rigid center with a soft outer ring, offering the clarity of RGP lenses with the comfort of soft lenses.
• Scleral Lenses: These are larger lenses that vault over the cornea and rest on the sclera (the white part of the eye). They can be more comfortable for individuals with advanced keratoconus.
• Piggybacking Lenses: This involves wearing a soft contact lens underneath a rigid gas permeable lens to improve comfort.

Surgical Treatments

• Corneal Cross-Linking (CXL): This procedure uses UV light and riboflavin (vitamin B2) drops to strengthen the corneal fibers, halting the progression of keratoconus. It’s most effective in the early to moderate stages of the disease. According to the American Academy of Ophthalmology (AAO), CXL is the only treatment proven to stop the progression of keratoconus.
• Intacs: These are small, crescent-shaped plastic inserts that are surgically placed into the cornea to flatten its shape and improve vision. Intacs can be used in combination with CXL.
• Corneal Transplant: In advanced cases where the cornea is severely scarred or thinning, a corneal transplant (keratoplasty) may be necessary. During this procedure, the damaged cornea is replaced with a healthy donor cornea. While effective, this is typically considered a last resort.

Home and Lifestyle Management

• Avoid rubbing your eyes, as this can worsen the condition.
• Wear sunglasses with UV protection to shield your eyes from harmful rays.
• Manage allergies effectively to reduce eye irritation and rubbing.
• Follow your doctor’s recommendations for lens care and wear.
• Attend regular eye exams to monitor the progression of the condition.

Prevention Tips

While keratoconus cannot always be prevented, especially if it’s genetically inherited, there are steps you can take to reduce your risk or slow its progression:

• Avoid Eye Rubbing: Rubbing your eyes can weaken the cornea. If you have allergies or dry eyes, use prescribed eye drops or medications to relieve itching and irritation.
• Protect Your Eyes from UV Light: Wear sunglasses that block 100% of UVA and UVB rays whenever you’re outdoors.
• Manage Chronic Conditions: If you have allergies, eczema, or other conditions that cause eye irritation, work with your doctor to keep them under control.
• Get Regular Eye Exams: Early detection is key. If you have a family history of keratoconus or other risk factors, schedule comprehensive eye exams regularly.
• Avoid Ill-Fitting Contact Lenses: Poorly fitted lenses can irritate the cornea. Always follow your eye doctor’s recommendations for lens type and wear schedule.
• Consider Genetic Counseling: If keratoconus runs in your family, genetic counseling may help you understand your risk and take preventive measures.

While these steps may not guarantee prevention, they can help protect your eye health and potentially slow the progression of the disease if it develops.

Emergency Warning Signs

Keratoconus is generally not an emergency, but certain symptoms require immediate medical attention. Seek emergency care if you experience:

• Sudden Vision Loss: If your vision becomes significantly blurred or you lose vision in one or both eyes suddenly, seek help immediately. This could indicate corneal hydrops, where fluid suddenly enters the cornea, causing severe swelling and vision loss.
• Severe Eye Pain: Intense pain, especially if accompanied by redness, could signal a corneal injury or infection.
• Sudden Onset of Flashes or Floaters: While not directly related to keratoconus, these symptoms could indicate a retinal issue, which requires urgent evaluation.
• Corneal Perforation: In rare cases, advanced keratoconus can lead to a tear or hole in the cornea. This is a medical emergency and requires immediate treatment to prevent permanent vision loss.

If you experience any of these symptoms, go to the nearest emergency room or contact your eye doctor immediately. Early intervention can prevent long-term damage and preserve your vision.

Living with Keratoconus

Keratoconus can be challenging, but with the right treatment and management, many people with the condition lead full, active lives. Advances in treatments like corneal cross-linking and scleral lenses have significantly improved outcomes for those with keratoconus. Support groups and resources, such as those offered by the National Keratoconus Foundation (NKCF), can provide valuable information and community support.

If you or a loved one has been diagnosed with keratoconus, work closely with your eye care team to develop a personalized treatment plan. Regular follow-ups and adherence to treatment recommendations are essential for managing the condition effectively.