Keratoconus: diagnosis and treatment simply explained
Published June 25, 2026
Keratoconus is a progressive disease of the cornea that gradually distorts it into a cone shape and blurs vision. It is a worrying diagnosis, often made in young people. Yet its management has changed profoundly: today, keratoconus can be stabilized in the vast majority of cases when it is detected early.
In this article, I explain how I make the diagnosis, how to stabilize the disease with cross-linking, how to restore vision with intracorneal ring segments and scleral lenses, and when a transplant may become necessary. I also discuss eye rubbing, the subject of my research, because it is the one factor you can act on.
What is keratoconus?
A corneal disease that progresses mainly in young people, but which can now be stabilized.
A cornea that changes shape
The cornea is the clear lens at the front of the eye. In keratoconus, its collagen loses strength and the cornea thins, especially in its lower part. It then gradually bulges into a cone shape, instead of keeping its regular dome.
This distortion creates irregular astigmatism that glasses cannot fully correct: vision becomes blurred, distorted, sometimes doubled. To better understand the different refractive errors, see my dedicated page.
When does it progress?
Keratoconus most often starts between the ages of 15 and 35. Progression can be significant in the first few years, and then gradual stabilization usually occurs around age 35–40. It is precisely because the disease affects young, active people that early diagnosis matters so much.
Warning signs
Certain signs should raise suspicion of keratoconus and prompt a consultation with corneal topography:
- Gradual loss of vision, unrelated to age
- A glasses prescription that changes often, without ever giving sharp vision
- Astigmatism that is poorly corrected, with distorted or double vision
- Intolerance to soft contact lenses and sensitivity to light
If you recognize several of these signs, don't wait: an early assessment genuinely changes the outlook.
Early diagnosis — topography and tomography
Everything relies on imaging of the cornea. At the practice, I use an Anterion® (Heidelberg Engineering), a swept-source anterior segment OCT, to characterize the cornea and closely monitor how it changes over time.
Topography & tomography
In a few seconds and without contact, the Anterion provides elevation maps and full corneal pachymetry, with automatic calculation of ectasia indices.
Detecting forme fruste keratoconus
Forme fruste keratoconus is an early form with no symptoms, visible only on imaging. Detecting it makes it possible to act before vision declines and to rule out risky laser surgery.
Assessing corneal strength
Additional tests analyze how the cornea deforms and objectively measure its biomechanical weakness, which is useful for both diagnosis and follow-up.
Comparing to decide
Tests are repeated and compared using differential maps. It is this pattern of change that guides the decision to perform cross-linking: progressing keratoconus warrants treatment.
Good to know: the assessment is performed during your consultation, with no injection or invasive product. Results are available immediately; I go through them with you and explain the strategy best suited to your situation.
Regaining functional vision — ring segments and lenses
Stabilizing is not always enough: vision also needs to be usable in everyday life. There are two main approaches, which are often complementary.
Intracorneal ring segments
Intracorneal ring segments are small implants inserted within the thickness of the cornea, through a tunnel created with a laser. They flatten and regularize the corneal surface, which can improve visual acuity and contact lens tolerance. Their effect is reversible: the ring segment can be removed if necessary.
They are mainly offered in moderate cases with contact lens intolerance, often in addition to cross-linking: CXL stabilizes biologically, while the ring segment regularizes optically. When implanted for keratoconus, they benefit from specific coverage by French national health insurance (Assurance Maladie) for approved indications. I perform this procedure myself at the practice.
Specialty contact lenses
When glasses are no longer enough, rigid lenses recreate a regular optical surface over the distorted cornea. Scleral lenses are a particularly attractive option: they rest on the white of the eye rather than on the cornea, which is then bathed in a reservoir of tears. Comfort and quality of vision are often excellent, even in advanced cases.
A study I contributed to showed that scleral lenses correct the complex optical aberrations of keratoconus better than conventional rigid lenses. For keratoconus, these lenses benefit from specific coverage with a prescription. I provide personalized fitting at the practice.
Corneal transplant — when does it become necessary?
Thanks to cross-linking and scleral lenses, more than 90% of patients keep their own cornea. A transplant is reserved for very advanced cases.
In which situations?
A transplant is considered when the cornea has become opaque in its center, when vision remains severely impaired despite treatment, or in cases of long-standing contact lens intolerance and corneal scarring. It is a decision made after a detailed evaluation, never as a first-line option.
DALK, the reference technique
For keratoconus, the reference technique is DALK (deep anterior lamellar keratoplasty). It replaces the diseased front layers while preserving the patient's own endothelium, which eliminates the specific risk of endothelial rejection and supports good long-term graft survival. When the patient's endothelium is itself damaged, a penetrating keratoplasty (PK, full-thickness transplant) may be indicated.
Recovery
Visual recovery is gradual, over 6 to 12 months, sometimes longer. Sutures are usually removed at around one year. Residual astigmatism is common and is corrected at a later stage. Lifelong follow-up is required.
At the practice: I personally perform corneal transplants (DMEK, DALK, penetrating keratoplasty) and oversee the entire care pathway, from the indication to long-term follow-up. To learn more, see my Corneal transplant page.
Your questions about keratoconus
Screening relies on corneal topography and tomography. At the practice, I use a swept-source OCT (Anterion) that maps the elevation and thickness of the cornea and calculates ectasia indices. This test detects forme fruste keratoconus, i.e. an early form with no symptoms, before any loss of vision occurs.
Cross-linking does not cure keratoconus or correct vision: it aims to halt or slow the progression of progressive keratoconus by stiffening the corneal collagen. Stabilization is reported in about 90% of patients at 5 years. It is a stabilizing treatment, to be combined with optical correction if needed.
Keratoconus creates irregular astigmatism that spectacle lenses cannot fully correct: vision remains blurred or distorted. Rigid or scleral lenses recreate a regular optical surface and often provide much better vision.
No. Thanks to cross-linking and scleral lenses, more than 90% of patients keep their own cornea. A transplant, most often a DALK that preserves the patient's endothelium, is reserved for very advanced cases with corneal opacity or contact lens intolerance.
No. LASIK is contraindicated in keratoconus, even mild or forme fruste, because laser ablation further weakens the cornea and carries a risk of ectasia. This is why systematic topographic screening is performed before any refractive surgery.
Get a clear picture of your keratoconus
Early diagnosis and regular follow-up change the outlook. I see patients at the OPHTALIFE practice in Boulogne-Billancourt, next to Paris, for a complete assessment of your cornea, and together we define the strategy best suited to your situation.
Related pages
Scientific references
This article is based on key publications and on my own research. Sources can be verified via their DOI or PubMed.
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1
Hage A, Knoeri J, Leveziel L, Majoulet A, Blanc J-V, Buffault J, Labbé A, Baudouin C. EYERUBBICS: The Eye Rubbing Cycle Study. J Clin Med. 2023;12(4):1529.
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2
Hage A, Knoeri J, Leveziel L, Majoulet A, Buffault J, Labbé A, Baudouin C. From ocular itching to eye rubbing: a review of the literature. J Fr Ophtalmol. 2023;46(2):173-184.
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3
Knoeri J, Mhenni R, Friquet C, Hage A, Cuyaubère R, Borderie M, Leveziel L, Bouheraoua N, Borderie V. Comparison of optical aberrations in keratoconus with scleral versus rigid gas permeable lenses. Eur J Ophthalmol. 2024;34(2):394-398.
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4
Wollensak G, Spoerl E, Seiler T. Riboflavin/ultraviolet-a-induced collagen crosslinking for the treatment of keratoconus. Am J Ophthalmol. 2003;135(5):620-627.
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5
Larkin DFP, Lanzetta P, Buchdahl J, et al. Effect of corneal cross-linking versus standard care on keratoconus progression in young patients: the KERALINK randomized controlled trial. Ophthalmology. 2021;128(11):1516-1526.
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6
Gomes JA, Tan D, Rapuano CJ, et al. Global consensus on keratoconus and ectatic diseases. Cornea. 2015;34(4):359-369.
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7
Mas Tur V, MacGregor C, Jayaswal R, O'Brart D, Maycock N. A review of keratoconus: diagnosis, pathophysiology, and genetics. Surv Ophthalmol. 2017;62(6):770-783.
The content of this website is for information purposes only and is not a substitute for a medical consultation. Any treatment decision should be made together with your ophthalmologist.