Expertise
Keratoconus
Keratoconus is a disease in which the cornea gradually thins and takes on a cone shape; vision becomes blurred and cannot be fully corrected with glasses. This page explains how the disease is assessed and by what logic treatment options are chosen.
Definition
What is keratoconus?
The cornea is the transparent, dome-shaped layer at the front of the eye and is among the principal structures that focus light. In keratoconus this layer thins and gradually takes on a cone shape. When the dome loses its regular form, light can no longer be gathered at a single point on the retina; the result is blurred, distorted vision that glasses do not fully correct.
The disease is usually noticed in adolescence and young adulthood and most often affects both eyes, although the change may differ between the two eyes. Its course varies from person to person: in some eyes it stays stable for years, in others it can progress.
For this reason, diagnosis rests not on a single measurement but on a comprehensive examination carried out together with corneal mapping. The treatment decision, too, is made with the physician according to this assessment and the course of the disease.
- When it begins
- Usually noticed in adolescence and young adulthood.
- Symptoms
- Blurred or distorted vision, a frequently changing glasses prescription, light sensitivity, halos and glare around lights.
- Risk factors
- A family history of keratoconus, an allergic (atopic) constitution, frequent and vigorous eye rubbing.
Assessment
How is it assessed?
When keratoconus is suspected, the examination proceeds with measurements that are painless and mostly do not require touching the eye. The following are the main steps you may encounter in the examination; which of them are needed varies from person to person.
Topography and tomography
It produces a map of the corneal surface. You rest your chin on the device and look at the light in the center; a few measurements are taken. Steepening and irregularity on the map are the main data in assessing corneal shape.
Pachymetry
This is the measurement of corneal thickness. The thickness map is used in deciding which treatments may be suitable. With some measurement methods the eye may be numbed with drops.
Biomechanical measurements
These are measurements that give additional information about the elasticity of the cornea; they support the diagnosis and are interpreted at follow-up. The device may also work by blowing a gentle puff of air in front of the eye.
The measurements are interpreted together; no single value establishes the diagnosis. If progression is suspected, the same measurements are repeated at set intervals and compared with one another. The physician determines the follow-up schedule.
Treatment
Treatment options
Depending on the physician's assessment, the following options may be considered singly or together. Which one is suitable depends on the stage of the disease, the corneal thickness and whether the disease is progressing.
Results may vary from person to person in any surgical or interventional procedure. This page is for information only; the treatment decision is made together with the physician after examination.
Questions
Frequently asked questions
Is cross-linking painful?
During the procedure the eye is numbed with drops. In the first days burning, stinging, watering and light sensitivity may occur; the severity varies from person to person. The physician gives the necessary drops and care recommendations.
From what age is it performed?
Age alone is not decisive. In keratoconus that is progressing it can also be considered in children and young people; the physician decides according to the examination findings.
Can I keep wearing lenses?
Lens wear is paused during the healing period after the procedure; the physician determines when it can be resumed. The need for special lenses may continue after the procedure.
Do glasses or lenses correct keratoconus?
Glasses and lenses do not treat the disease; they support vision. In the early stage glasses may be sufficient; as corneal irregularity increases, special lenses may be needed. Progression of the disease is assessed separately.
Is rubbing the eyes harmful?
Frequent and vigorous eye rubbing is one of the known risk factors for keratoconus. If there is itching, its cause, for example eye allergy, is investigated together with the physician.
Does keratoconus lead to loss of vision?
It is a disease that can be monitored when followed regularly; in eyes that progress, the quality of vision may decline. In advanced cases a corneal transplant may be considered. It is therefore important not to miss check-ups.
Record
Publications on this subject
Six of Prof. Dr. Yusuf Yıldırım's studies on keratoconus, ordered by number of citations.
All publications- 2012
Accelerated corneal crosslinking concurrent with laser in situ keratomileusis
Journal of Cataract & Refractive Surgery · 38(8):1424
115 citations
DOI (opens in a new tab) - 2015
Accelerated Corneal Collagen Cross-Linking in Thin Keratoconic Corneas
Journal of Refractive Surgery · 31(6):386
53 citations
DOI (opens in a new tab) - 2014
Evaluation of Corneal Stromal Demarcation Line after Two Different Protocols of Accelerated Corneal Collagen Cross-Linking Procedures Using Anterior Segment Optical Coherence Tomography and Confocal Microscopy
Journal of Ophthalmology · 2014
40 citations
DOI (opens in a new tab) - 2019
Different accelerated corneal collagen cross-linking treatment modalities in progressive keratoconus
Eye and Vision · 6(1):16
39 citations
DOI (opens in a new tab) - 2020
Complications of accelerated corneal collagen cross-linking: review of 2025 eyes
International Ophthalmology · 40(12):3269
32 citations
DOI (opens in a new tab) - 2017
Comparison of Accelerated Corneal Collagen Cross-linking Types for Treating Keratoconus
Current Eye Research · 42(7):971
28 citations
DOI (opens in a new tab)
Data are taken from OpenAlex and Web of Science; last updated October 14, 2026.
Related articles