Keratoconus

Keratoconus usually begins quietly and gets worse over years. Early on, the main signs are:

• Blurry or distorted vision that is not fully fixed by new glasses.
• Glasses prescription that changes a lot from year to year, especially the astigmatism number.
• Halos, glare, or starbursts around lights, especially at night.
• Ghosting or double vision in one eye.
• Eye strain or headaches from squinting to see.
• Increased sensitivity to bright light.

As keratoconus progresses, soft glasses or simple contact lenses no longer give sharp vision and rigid (gas-permeable, hybrid, or scleral) contact lenses are usually needed. In a small number of eyes, the back of the cornea ruptures and the cornea fills with fluid (corneal hydrops). This causes sudden pain, a hazy white spot on the cornea, and a big drop in vision. Hydrops is not a true emergency but should be seen by an eye doctor within a day or two ¹.

Keratoconus is caused by a mix of genes and outside factors. The collagen fibers that hold the cornea in its smooth dome shape are weaker than normal, so over time the cornea slowly thins and bulges out. It is not contagious and is not caused by any one thing the patient did ².

Things that raise the risk of keratoconus:

• Hard or frequent eye rubbing. The strongest changeable risk factor. Even gentle daily rubbing for years can push a vulnerable cornea toward keratoconus. Several large studies show eye rubbers have a 3-10 times higher risk ⁵.
• Eye allergies, eczema, and asthma. All of these make the eyes itch, which leads to rubbing.
• Family history of keratoconus. First-degree relatives are about 6 times more likely to develop keratoconus.
• Down syndrome and certain connective tissue conditions (Ehlers-Danlos, Marfan).
• Sleep apnea and floppy eyelid syndrome (the eyelids flip up easily during sleep).
• Ancestry. Keratoconus is more common in people from the Middle East, South Asia, and parts of the Mediterranean.
• Age. Disease usually starts in the teens or 20s. It rarely starts after age 40.

Eye rubbing is so important that even non-allergic rubbing (just a habit) has been shown to be a major behavioral risk factor for keratoconus on its own ⁶. Treating the underlying itch and breaking the habit is one of the most powerful things a patient can do.

Treatment for keratoconus depends on how advanced it is and whether it is getting worse. The first goals are to stop progression with corneal cross-linking, and to give the patient sharp vision today with the right glasses or contact lenses ¹.

Vision correction:

• Glasses or soft contact lenses — fine for mild keratoconus.
• Rigid gas-permeable contact lenses — sit on the cone and give a smooth optical surface; very common in moderate keratoconus.
• Hybrid lenses — rigid center with a soft skirt for comfort.
• Scleral contact lenses — large rigid lenses that vault over the cornea and rest on the white of the eye. Often the best comfort and vision for advanced keratoconus.
• Custom soft contact lenses — newer option for moderate keratoconus.

Stopping progression — corneal cross-linking (CXL):

• A 30-90 minute office procedure. Riboflavin (vitamin B2) drops are placed on the cornea, then a controlled dose of ultraviolet (UVA) light shines on the eye. This makes new chemical bonds in the corneal collagen, stiffening the cornea.
• In large trials, cross-linking stops keratoconus from getting worse in about 95% of treated eyes over several years. It does not reverse the cone — it locks it in place ⁴.
• Two main techniques: epi-off (the surface skin of the cornea is gently removed first; recovery takes about a week and is more painful) and epi-on (the surface is left in place; gentler recovery, but slightly less effective in studies so far) ⁷.
• Best done early, while the cornea is still thick enough and vision is still good with glasses or contact lenses.

Reshaping the cornea:

• Intracorneal ring segments (e.g., Intacs) — small clear plastic arcs placed inside the cornea to flatten the cone and improve contact lens fit. Used for moderate keratoconus.
• Topography-guided laser treatment combined with cross-linking is offered in some cornea practices for selected cases.

Corneal transplant (for advanced disease):

• Deep anterior lamellar keratoplasty (DALK) — replaces the front layers of the cornea but leaves the patient's healthy inner layer in place. Lower risk of rejection than a full-thickness transplant. Preferred for keratoconus when possible.
• Penetrating keratoplasty (PK) — full-thickness corneal transplant. Used when DALK is not possible.
• Vision recovery after a corneal transplant takes 6-12 months. Many people still need glasses or contact lenses after surgery.

Most people with keratoconus see well for a lifetime with the right care. Day-to-day habits that help:

• Do not rub your eyes. Treat allergies, dry eye, and lid problems so your eyes do not itch. Wear sunglasses outdoors to cut glare and irritants.
• See a cornea specialist every 6-12 months until your keratoconus is clearly stable. Tracking with imaging is the only reliable way to know if the disease is progressing and whether cross-linking is needed.
• Take great care of your contact lenses. Always wash your hands before touching them. Never sleep in soft or rigid contacts unless approved. Use only solutions the doctor recommends, not water.
• Know infection warning signs. A painful, red, light-sensitive eye with discharge in a contact lens wearer is a same-day emergency.
• Wear safety eyewear. A blow to a keratoconic cornea can cause more damage than to a normal one.
• Be careful with laser eye surgery. Standard LASIK is not safe in keratoconus. Some patients with stable, cross-linked corneas may be candidates for very limited surface laser, but only after thorough imaging by a cornea specialist.
• Plan financially. Specialty contact lenses, cross-linking, and transplants are usually partly covered by insurance, but copays and out-of-pocket costs can add up. Ask the practice for a clear cost breakdown.