Keratoconus : Causes, symptoms & treatment options in Turkey

What is keratoconus and who does it affect?

Keratoconus, from the Greek for cone-shaped cornea, is a progressive, non-inflammatory condition in which the cornea, normally a smooth dome, gradually thins and bulges forward into an irregular conical shape. This distortion scatters incoming light instead of focusing it cleanly on the retina, causing progressively blurred and distorted vision.

It typically appears in the teenage years and continues to evolve through the 30s and 40s before often stabilizing. It is almost always bilateral, though it may affect one eye more noticeably than the other.

A 2021 systematic review published in Ophthalmology (AAO journal) estimated global keratoconus prevalence at approximately 1.38 per 1,000 people, with significantly higher rates in the Middle East, South Asia, and North Africa, populations disproportionately represented among international patients seeking treatment at Turkish eye centers.

What are the symptoms of keratoconus and when should you see a doctor?

Keratoconus is notoriously difficult to diagnose early because its initial symptoms mimic common refractive errors. Here's what to watch for:

• Blurred or distorted vision that keeps changing, spectacle prescriptions that need updating every few months.
• Monocular diplopia: seeing 'ghost images' with one eye, even when wearing glasses.
• Increased sensitivity to light (photophobia) and glare, particularly at night.
• Halos around lights and difficulty driving after dark.
• Frequent eye rubbing, which can itself accelerate corneal thinning.
• A sensation of eye irritation without apparent cause.

The key red flag is a rapidly changing vision. If your prescription seems to shift every 6-12 months and glasses no longer fully correct your vision, request a corneal topography scan from your ophthalmologist. This map of the cornea's surface is the definitive diagnostic tool, and early detection fundamentally changes the treatment options available to you.

What are the stages of keratoconus?

The Amsler-Krumeich grading system is the internationally accepted classification for keratoconus severity. Your stage determines your treatment path:

Important: Early-stage keratoconus is the most treatable. If you are between stages 1 and 2 and your condition is still progressing, cross-linking remains the most effective intervention to prevent you from reaching advanced stages.

What causes keratoconus?

Several suspicious factors are regularly highlighted in medical research on the possible causes of keratoconus.

Genetic predisposition

The first area of investigation is genetic. Many cases of keratoconus have been recorded among members of the same family, which suggests a possible hereditary transmission. Even though no single gene has been identified as responsible so far, the family component is now almost undisputed.

If a close relative has keratoconus, it may be helpful to have regular eye exams for other family members, especially children and adolescents.

Aggravating environmental factors

In addition to genetics, external factors may contribute to the development or progression of keratoconus. The most commonly cited are:

• Excessive eye rubbing, often linked to allergies or dry eyes, which can weaken the cornea.
• Prolonged or improper use of contact lenses, especially rigid ones, can also exacerbate corneal deformation in some people.
• Repeated exposure to UV rays without eye protection.

These seemingly harmless everyday actions can have a direct impact on eye health if they are repeated.

A possible hormonal origin?

Since keratoconus often appears in adolescence or early adulthood, some researchers suspect a hormonal influence. Hormonal changes could affect the structure and strength of the cornea, making it more vulnerable to deformation.

Associations with other diseases

Keratoconus is sometimes associated with genetic diseases or rare syndromes, such as:

• Down syndrome (trisomy 21).
• Marfan syndrome, which affects connective tissue.
• Osteogenesis imperfecta, a disease that weakens bones.

These links suggest that certain connective tissue weaknesses may also play a role in the development of the disease.

What are the keratoconus treatment options available in Turkey?

Keratoconus management follows a staged protocol:

1. Stabilizing the cornea to halt the disease's progression.
2. Correcting the visual disturbances caused by corneal deformation.

The right treatment depends entirely on your stage and whether the disease is still progressing.

Corneal cross-linking (CXL): The foundation of keratoconus treatment

Cross-linking is the only evidence-based treatment that stops keratoconus from getting worse. It works by introducing riboflavin (vitamin B2) drops into the corneal stroma, then activating them with controlled UVA light to form new chemical bonds between collagen fibrils, making the cornea significantly stiffer and more resistant to progressive deformation.

A 2023 Cochrane systematic review (the gold standard in clinical evidence) confirmed that accelerated CXL halts progression in over 90% of treated eyes at 3-year follow-up. It does not reverse existing damage, but it stops the clock, which is precisely what is needed in early-to-moderate disease.

At Turquie Santé partner clinics, CXL is performed under local anaesthetic eye drops, takes approximately 60-90 minutes, and requires no hospitalisation. Most patients experience temporary light sensitivity and mild discomfort for 48–72 hours, with functional vision returning within 1-2 weeks.

Intracorneal ring segments (ICRS): Reshaping without transplant

When vision correction with spectacles or contact lenses becomes inadequate, and the disease is stable, intracorneal ring segments can be surgically inserted into the corneal stroma to flatten and regularize the corneal surface. The result is both structural improvement and better optical correction.

ICRS can be combined with CXL in the same procedure, a combined approach increasingly used at Turkish corneal centres for moderate-stage keratoconus. One or two ring segments are selected based on precise corneal topography measurements. The procedure is reversible.

Topography-guided Excimer laser (PRK/Trans-PRK)

For patients who have completed CXL and whose disease is now stable, topography-guided laser ablation can further regularize the corneal surface and reduce residual myopia and astigmatism. This is not a primary treatment for keratoconus but an adjunct for improving vision after stabilisation.

Corneal transplantation: When other options are exhausted

Reserved for advanced keratoconus (Stage 3-4) when the cornea is too irregular or scarred to be managed conservatively. Two main approaches:

• DALK (Deep Anterior Lamellar Keratoplasty): partial transplant preserving the patient's own endothelium, lower risk of rejection, and generally preferred when the inner layers are healthy.
• PKP (Penetrating Keratoplasty): full-thickness corneal transplant for the most severe cases with central scarring.

Clinical note: A 2022 meta-analysis in Ophthalmology found that DALK has a lower endothelial rejection rate than PKP (2.4% vs 7.6% at 5 years) with equivalent long-term visual outcomes, making it the preferred technique at most Turquie Santé partner centres.