Keratoconus

Your cornea is normally round and dome-shaped, like the surface of a ball. In keratoconus, the cornea loses its structural strength and begins to thin, especially in the center or just below center. As the tissue weakens due to a combination of biomechanical, genetic, and environmental factors, the cornea bulges forward into an irregular cone-like shape.

This change in shape causes light rays to scatter instead of focusing clearly on the back of your eye. The result is vision that becomes increasingly blurry, distorted, and difficult to correct with regular glasses.

Keratoconus often develops during the teenage years or early twenties, though it can appear at any age. Common early symptoms include noticing that your vision seems slightly blurred or that lights appear streaky or hazy, especially at night.

• Frequent changes in your eyeglass or contact lens prescription
• Increased sensitivity to bright lights and glare
• Eye strain and discomfort when reading or using screens
• Seeing multiple ghost images or halos around lights

As keratoconus progresses, everyday tasks can become challenging. You may find it harder to read street signs, recognize faces from a distance, or see clearly while driving at night. Many people notice that their vision fluctuates throughout the day or that one eye performs worse than the other.

The distortion caused by the irregular corneal shape can make straight lines appear wavy or bent. Activities that require sharp vision, such as reading fine print or working on detailed projects, may become frustrating and tiring.

While keratoconus typically progresses slowly, certain symptoms warrant urgent evaluation. Sudden changes in vision quality, sharp eye pain, or a dramatic decrease in vision clarity can signal acute complications. One of the most important is acute corneal hydrops, which occurs when fluid suddenly breaks through into the cornea.

• Sudden marked blurring or a painful vision drop with new corneal whitening, opacity, tearing, and light sensitivity may indicate acute corneal hydrops
• Sudden clouding or haziness in your vision that develops quickly
• Severe eye pain or sensitivity to light that interferes with daily activities
• A sudden drop in vision that your current lenses cannot improve
• Persistent redness or swelling in or around your eye

If these occur, seek urgent eye care the same day or visit an emergency department if symptoms are severe and you cannot reach an eye care provider promptly.

In the earliest stages of keratoconus, when the corneal irregularity is mild, regular eyeglasses or soft contact lenses may provide adequate vision correction. Many patients achieve satisfactory vision with these conventional options at the beginning of the disease. However, as the condition progresses and the cornea becomes more irregular, glasses and soft lenses typically become less effective.

We monitor your vision closely during this stage. When you notice that new glasses no longer provide the clarity they once did, or when your prescription changes rapidly, it may be time to consider specialized contact lens options.

Several specialty lens designs bridge the gap between standard soft lenses and rigid options. Custom soft lenses made specifically for keratoconus can provide better vision and comfort than regular soft lenses in mild to moderate cases. These lenses are designed with thicker centers and specialized curvatures to vault over the cone.

Hybrid lenses combine a rigid center for clear optics with a soft outer skirt for comfort. Piggyback systems involve wearing a soft lens underneath a rigid lens to improve comfort and stability. Each option has benefits and limitations, and your eye care provider will help determine which approach best suits your corneal shape, vision needs, and comfort preferences.

• Custom keratoconus soft lenses may work well for milder irregular astigmatism
• Hybrid lenses offer rigid-lens clarity with improved initial comfort for some patients
• Piggyback systems can help when rigid lenses alone are uncomfortable or unstable
• All specialty lenses require careful fitting, monitoring for corneal health, and adaptation time

Rigid gas permeable lenses are often the next step when glasses no longer work well. These firm lenses vault over the irregular corneal surface and create a smooth optical surface, often improving vision for many keratoconus patients. The tear layer that fills the space between the lens and your cornea helps correct the irregular shape.

Scleral lenses are larger specialty lenses that rest on the white part of your eye rather than directly on the cornea. They offer excellent comfort and vision for advanced keratoconus because they completely vault over the cone. Many patients find scleral lenses easier to wear for long hours compared to smaller rigid lenses. However, adaptation to any rigid or specialty lens system can take time, and some patients experience fogging, discomfort, or difficulty with insertion and removal. Careful fitting and regular monitoring of corneal health are essential for success.

Corneal cross-linking is a procedure designed to halt or slow the progression of keratoconus. During this treatment, we apply riboflavin drops to your cornea and then activate them with ultraviolet light. This process creates new bonds between collagen fibers in your cornea, strengthening the tissue and making it more resistant to bulging.

Cross-linking is most effective when performed in patients with documented progressive keratoconus, especially younger individuals. It has become a current standard of care for progressive keratoconus. While the primary goal is to stabilize the cornea and prevent further deterioration, some patients also experience modest corneal flattening and improvements in vision or optical aberrations over time.

• Epithelium-off and transepithelial approaches are used, with varying protocols and evidence; availability and insurance coverage differ
• Common short-term effects include pain, light sensitivity, temporary corneal haze, and fluctuating vision during the healing period
• Risks are generally low but can include infection, delayed healing, scarring, sterile infiltrates, and reactivation of herpes simplex virus in patients with a history of herpetic eye disease
• After the procedure, avoid eye rubbing, follow your prescribed drop regimen carefully, and attend all follow-up appointments
• Cross-linking is not suitable for all patients, such as those with active infection, significant scarring, very thin corneas without protocol modification, or poor healing potential

Intacs are small, curved plastic segments that may be inserted into your cornea to help reshape it and reduce the cone-like bulge. These implants work by flattening the central cornea and making its shape more regular. The procedure involves creating tiny channels in your cornea where the segments are positioned.

Intracorneal ring segments generally improve the optical shape of the cornea and may enhance contact lens tolerance, but they do not reliably halt disease progression on their own. When progression is documented, corneal cross-linking is usually the treatment used to stabilize the cornea. This option is typically reserved for specific cases where other treatments have not provided sufficient benefit or when contact lens wear is not tolerated. The segments can be removed or replaced if needed.

• Possible complications include infection, segment extrusion or migration, glare and halos, and variable refractive outcomes
• Some patients require additional procedures or lens adjustments after ring implantation
• Careful patient selection and realistic expectations are important for satisfaction

Corneal transplant surgery is considered only when keratoconus has progressed to the point where vision cannot be adequately corrected with lenses or when corneal scarring has developed. In a transplant procedure, we replace the damaged central portion of your cornea with healthy donor tissue. Modern techniques such as deep anterior lamellar keratoplasty allow us to replace only the affected front layers in many cases, while full-thickness penetrating keratoplasty is used when deeper layers are involved.

Thanks to earlier intervention with cross-linking and advanced contact lenses, fewer patients require transplant surgery today than in the past. When transplant does become necessary, the success rates are generally good, though the process involves significant considerations.

• Visual rehabilitation can take many months to over a year as the cornea heals and sutures are removed
• There is a risk of transplant rejection, especially with full-thickness grafts, requiring lifelong monitoring
• Post-operative astigmatism is common and may require rigid or scleral contact lenses even after successful surgery
• Suture management, infection prevention, and close follow-up care are essential parts of recovery
• Despite challenges, most patients achieve meaningful vision improvement and stability after transplant