{"id":1834,"date":"2026-10-20T08:52:37","date_gmt":"2026-10-20T08:52:37","guid":{"rendered":"https:\/\/laseristanbulclinic.com\/eye-glossary\/keratoconus\/"},"modified":"2026-10-20T12:56:57","modified_gmt":"2026-10-20T12:56:57","slug":"keratoconus","status":"publish","type":"page","link":"https:\/\/laseristanbulclinic.com\/en\/eye-glossary\/keratoconus\/","title":{"rendered":"Keratoconus: What It Is, Symptoms, Causes and Treatment"},"content":{"rendered":"\n
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  1. Home<\/a><\/li>
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  4. Keratoconus: What It Is, Symptoms, Causes and Treatment<\/span><\/li><\/ol><\/div>\t\t\t

    Keratoconus: What It Is, Symptoms, Causes and Treatment<\/h1>\n\t\t\t\t\t\t

    Medically reviewed by {{surgeon}}<\/span><\/strong>, {{surgeon’s title and specialty}}<\/span>, on {{review date}}<\/span>. Last updated {{date}}<\/span>.<\/p>\n\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t

    \"Close-up<\/figure><\/div>\n\t\t\t<\/div><\/div>\n<\/section>\n\n\n\n\n
    \n\t\t<\/svg>Definition<\/span>\n\t\t\t

    Keratoconus<\/strong> (noun, pronounced ker-uh-toh-KOH-nus)<\/em>: keratoconus is an eye condition in which the clear front surface of the eye, the cornea, gradually thins and bulges forward into a cone shape. The cone changes how light focuses inside the eye, causing blurred and distorted vision that glasses correct less and less well. It usually starts in the teens or early twenties and is managed by a cornea specialist; at Laser Istanbul Clinic, keratoconus care is led by Do\u00e7. Dr. Muhammet Derda \u00d6zer (Do\u00e7. means Associate Professor).<\/p>\n\t\t<\/div><\/div><\/div><\/div><\/section>\n\n\n\n\n

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    Keratoconus: key facts<\/h2><\/div>\n\t\t\t\t\t<\/div>\n\t\t\t
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    <\/svg>What happens<\/span><\/dt>
    The cornea thins and steepens into a cone, causing irregular astigmatism and short-sightedness that keep changing<\/dd><\/dl><\/div>\n\t\t\t\t
    <\/svg>Usual age at start<\/span><\/dt>
    Late teens to early twenties; it can progress over 10\u201320 years (AAO)<\/dd><\/dl><\/div>\n\t\t\t\t
    <\/svg>How common<\/span><\/dt>
    Often quoted as about 1 in 700 people; published estimates range from 0.17 to 40 per 1,000 depending on how it is measured and where (EyeWiki; 2026 clinical practice guideline)<\/dd><\/dl><\/div>\n\t\t\t\t
    <\/svg>Main known risk factors<\/span><\/dt>
    Eye rubbing, eye allergy, family history, some connective-tissue conditions, Down syndrome<\/dd><\/dl><\/div>\n\t\t\t\t
    <\/svg>Key test<\/span><\/dt>
    Corneal topography or tomography (a map of the cornea’s shape and thickness)<\/dd><\/dl><\/div>\n\t\t\t\t
    <\/svg>Main treatments<\/span><\/dt>
    Glasses and special contact lenses; corneal cross-linking to stop progression; ring segments; corneal transplant in advanced cases<\/dd><\/dl><\/div>\n\t\t\t\t
    <\/svg>Specialist<\/span><\/dt>
    Cornea specialist (ophthalmologist); at Laser Istanbul Clinic, Do\u00e7. Dr. Muhammet Derda \u00d6zer<\/dd><\/dl><\/div>\n\t\t\t<\/div>\n\t\t<\/div><\/div><\/div><\/section>\n\n\n\n\n
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    What is keratoconus?<\/h2><\/div><\/div>

    Keratoconus is a progressive disease of the cornea, the dome-shaped clear window at the front of the eye. The cornea normally holds its round shape because its collagen fibres are strong and evenly arranged. In keratoconus those fibres weaken, so the cornea slowly thins, usually in the lower centre, and pushes forward into a cone. Because the cornea provides most of the eye’s focusing power, even a small change in its shape matters: light no longer meets in a single point, and vision becomes blurred, doubled or streaked.<\/p>\n

    The word comes from the Greek kerato<\/em> (cornea) and konos<\/em> (cone). It is not contagious, and it is not caused by wearing glasses or contact lenses.<\/p><\/div>

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    How common is keratoconus?<\/h3>

    EyeWiki, the American Academy of Ophthalmology’s online reference, says the prevalence is often reported as 1 in 700, with higher rates in Middle Eastern, Indian, Chinese and Australian populations. A 2026 clinical practice guideline in Clinical Ophthalmology<\/em> notes that published estimates range from 0.17 to 40 cases per 1,000 people, because studies use different diagnostic criteria and imaging technology. Better scanners now find milder cases that were missed in the past.<\/p><\/div><\/div>

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    Does keratoconus get worse over time?<\/h3>

    Often, yes, at least for a while. The American Academy of Ophthalmology (AAO) says keratoconus typically begins in the late teens to early twenties and can progress over 10 to 20 years. EyeWiki describes onset in early adolescence with progression into the mid-twenties and thirties, although it can start earlier or continue later. It tends to progress faster in children and young people: a 2026 European consensus statement on paediatric keratoconus cites progression in 88% of children in published studies, with some eyes steepening by up to 5 dioptres in a year. How an individual eye will behave cannot be predicted without regular scans.<\/p><\/div><\/div><\/div>\t<\/div><\/div><\/div>\n<\/section>\n\n\n\n\n

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    What causes keratoconus?<\/h2>\n\t\t\t

    The exact cause is not known. Current understanding is that keratoconus results from a combination of inherited tendencies and things that physically or chemically stress the cornea.<\/p>\n\t\t\t

    Factor<\/th>What the evidence says<\/th><\/tr><\/thead>
    Eye rubbing<\/strong><\/th>The strongest risk factor you can change. The 2026 guideline reports an odds ratio of 5.22 for eye rubbing; the paediatric consensus says children who rub their eyes are about three times as likely to develop keratoconus. The AAO advises avoiding eye rubbing because it can damage thin corneal tissue and make symptoms worse<\/td><\/tr>
    Family history<\/strong><\/th>About 1 in 10 people with keratoconus have an affected parent (AAO). The 2026 guideline reports an odds ratio of 6.67 for family history<\/td><\/tr>
    Eye allergy and atopy<\/strong><\/th>Allergic eye disease raises the risk (odds ratio 2.21 in the 2026 guideline), mainly because it makes people rub their eyes. Controlling the allergy with drops is part of treatment<\/td><\/tr>
    Connective-tissue conditions<\/strong><\/th>Marfan syndrome and Ehlers-Danlos syndrome are associated with keratoconus (AAO)<\/td><\/tr>
    Down syndrome<\/strong><\/th>Listed by EyeWiki as a risk factor<\/td><\/tr>
    Other associations<\/strong><\/th>EyeWiki also lists sleep apnoea, hypothyroidism and hormonal changes during pregnancy. These are associations, not proven causes<\/td><\/tr><\/tbody><\/table><\/div>

    Not a cause:<\/strong> diabetes and sex showed no significant association in the 2026 guideline’s review.<\/p><\/div>\t<\/div><\/div><\/div><\/section>\n\n\n\n\n

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    \"Corneal<\/div><\/div>\n\t\t
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    What are the symptoms of keratoconus?<\/h2>\n\t\t\t\t\t\t

    Early keratoconus can cause no symptoms or just a little blur, which is why it is often found at a routine eye test or before laser eye surgery. As the cone grows, the AAO lists these symptoms:<\/p>\n\t\t\t\t\t\t