Quick answer: Keratoconus is diagnosed with corneal tomography, a painless scan that maps the shape and thickness of the front and back of the cornea. It often shows keratoconus before vision is badly affected. Repeating the scan over time shows whether keratoconus is getting worse, which decides whether cross-linking is needed. A glasses prescription with astigmatism that keeps changing is the most common early clue.
Key Takeaways
- Corneal tomography is the key test for keratoconus. It can detect early keratoconus before symptoms are obvious.
- Common early signs are blurred or distorted vision and a glasses prescription, especially astigmatism, that keeps changing.
- Keratoconus usually starts in the teens or twenties. Eye rubbing, allergic eye disease and a family history increase the risk.
- Progression is confirmed by comparing scans over time. Cross-linking is often recommended at diagnosis in young patients, and in older patients when progression is confirmed.
- Anyone with keratoconus should not have LASIK, so screening before laser vision correction is essential.
What Are the First Signs of Keratoconus?
The first signs of keratoconus are usually changes in vision rather than pain or redness. Keratoconus makes the cornea thinner and pushes it into an irregular cone shape, which scatters light. Look out for:
- A glasses prescription, especially astigmatism, that changes every few months
- Blurred or distorted vision that new glasses do not fully correct
- Ghost images or double vision in one eye
- Glare and halos around lights at night
- Sensitivity to light and eye strain
- Clearly different vision between the two eyes
Read more about symptoms of keratoconus.
Who Should Be Checked for Keratoconus?
You should be checked for keratoconus if you have any of the signs above, or if you are at higher risk:
- Teenagers and young adults whose astigmatism is increasing
- Brothers, sisters and children of someone with keratoconus
- People who rub their eyes often, or have allergic eye disease
- Anyone considering LASIK, SMILE Pro or PRK
Read about the causes of keratoconus.
Which Tests Are Used to Diagnose Keratoconus?
A keratoconus assessment combines an eye examination with corneal imaging. At Sayyad Eye Center, it includes:
| Test | What it shows |
|---|---|
| Corneal tomography (Pentacam in New Cairo, CSO MS-39 in Mohandeseen) | A map of the front and back surfaces of the cornea and its thickness at every point, including the BAD score (Belin/Ambrósio Enhanced Ectasia Display), which shows how far the cornea is from normal. This is the most important test. |
| Pachymetry | Corneal thickness, including the thinnest point |
| Keratometry and topography | How steep the cornea is and how irregular its shape is |
| Anterior segment OCT (SOLIX) | A cross-section image of the corneal layers |
| Slit-lamp examination | Signs of keratoconus inside the cornea, scarring and allergic eye disease |
| Vision and prescription | How much vision can be corrected with glasses, and whether a rigid lens would help |
If you wear rigid contact lenses, you may be asked to stop wearing them for a period before the scan, because they temporarily change the shape of the cornea.
How Is Keratoconus Different From Regular Astigmatism?
Regular astigmatism and keratoconus both blur vision, but they behave very differently.
| Regular astigmatism | Keratoconus | |
|---|---|---|
| Corneal shape | Evenly curved, like a rugby ball | Thinned and irregular, pushed into a cone |
| Glasses | Correct vision fully | Often do not give fully clear vision |
| Over time | Usually stable | Can get worse, especially in the teens and twenties |
| Tomography | Symmetrical pattern, normal thickness | Localized steepening and thinning |
| LASIK | Often possible | Not performed |
How Do Doctors Know Whether Keratoconus Is Getting Worse?
Progression is judged by comparing tomography scans taken months apart on the same device. According to the Global Consensus on Keratoconus and Ectatic Diseases, progression means a consistent change in at least two of the following: the front surface of the cornea becomes steeper, the back surface becomes steeper, or the cornea becomes thinner. Vision does not have to get worse for progression to be confirmed, which is why scans matter more than how you see.
I repeat scans regularly, more often in children and teenagers, whose keratoconus tends to progress faster.
What Happens After Keratoconus Is Diagnosed?
The treatment plan depends on whether keratoconus is progressing and how much it affects your vision.
- Stop rubbing your eyes, and treat any eye allergy, because rubbing can make keratoconus worse.
- Monitoring with repeat scans if keratoconus is mild and stable.
- Corneal cross-linking to stop keratoconus from getting worse. In young patients it is often recommended at diagnosis; in older patients it is usually done when progression is confirmed. The decision depends on each case. See treatment of keratoconus.
- Rigid or scleral contact lenses for the clearest vision. See rigid lenses for keratoconus.
- Corneal rings in selected cases. See corneal ring implantation.
- Corneal transplant, usually DALK, only in advanced cases.
Read more about the stages of keratoconus and whether keratoconus causes blindness.
How Much Does Keratoconus Treatment Cost?
See the price guides for corneal cross-linking and corneal rings.
What Patients Say (Google Reviews)
My daughter’s experience with Dr. Fouad El Sayyad was very successful, thanks to God and then Dr. Fouad. It was a corneal cross-linking procedure, followed by the use of rigid contact lenses. … They are honest in how they deal with each case.
Google review · Sayyad Eye Center, Mohandeseen · October 2026 · translated from Arabic
The examination and diagnosis are done professionally and precisely, with attention to every detail of the case, first by the consultant’s assistant and then by the consultant, Dr. Fouad, who welcomes you with a smile … The examination is done carefully before the diagnosis, and then he decides on the treatment, with advice and answers to every question without impatience.
Google review · Sayyad Eye Center, New Cairo · October 2026 · translated from Arabic
Where Does Dr. Fouad El Sayyad See Patients?
- Sayyad Eye Center, Mohandeseen: 3A Gameat El Dowal El Arabeya St., Sphinx Square.
- Sayyad Eye Center, New Cairo: Medical Park 2, opposite New Cairo Court.
To book an appointment with Dr. Fouad El Sayyad, call or WhatsApp 01000088168.
Frequently Asked Questions
How do I know if I have keratoconus?
Only an eye examination with corneal tomography can confirm keratoconus. Suspect it if your astigmatism keeps changing, your glasses no longer give clear vision, or you see ghost images or halos. Early keratoconus can be found on a scan before you notice any symptoms.
What is the best test for keratoconus?
Corneal tomography is the most important test. It maps the front and back surfaces of the cornea and its thickness, so it can detect early keratoconus that a standard vision test or topography of the front surface alone may miss.
At what age does keratoconus start?
Keratoconus usually starts in the teenage years and can progress into the twenties and thirties. When it starts in childhood, it is often more advanced at diagnosis and may progress faster, so children need closer monitoring.
Is keratoconus hereditary?
Keratoconus can run in families, but the pattern is not predictable. If you have keratoconus, your brothers, sisters and children should have a corneal scan, especially in their teenage years.
How often should keratoconus be checked?
Your doctor will advise you based on your age and how stable your scans are. Children and teenagers need more frequent scans, because their keratoconus tends to progress faster. After cross-linking, scans continue to confirm the cornea has stabilized.
Can keratoconus be confused with astigmatism?
Yes. Early keratoconus often looks like ordinary astigmatism in a glasses prescription. The difference is that keratoconus causes irregular astigmatism that changes over time and is not fully corrected by glasses. Tomography tells them apart.
Does eye rubbing cause keratoconus?
Frequent eye rubbing is strongly linked to keratoconus and to its progression, especially in people who are already prone to it. Treating eye allergy and stopping rubbing is an important part of treatment.
Can I have LASIK if my scan shows early keratoconus?
No. LASIK can weaken a cornea with keratoconus and make it worse. That is why every patient is screened with tomography before laser vision correction. Other options are discussed after a full assessment.
This article is for general education and does not replace an eye examination. Treatment decisions depend on your own eye assessment.
References
This article is for general education and does not replace an eye examination. Treatment decisions depend on your own eye assessment.
FAQS
-
How do I know if I have keratoconus?
Only an eye examination with corneal tomography can confirm keratoconus. Suspect it if your astigmatism keeps changing, your glasses no longer give clear vision, or you see ghost images or halos. Early keratoconus can be found on a scan before you notice any symptoms.
-
At what age does keratoconus start?
Keratoconus usually starts in the teenage years and can progress into the twenties and thirties. When it starts in childhood, it is often more advanced at diagnosis and may progress faster, so children need closer monitoring.
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