What Is Keratoconus?}

What is Keratoconus?


Heather Colman

Keratoconus is a degenerative non-inflammatory disorder of the eye in which structural changes within the cornea cause it to thin and change to a more conical shape than its normal, even curve. Keratoconus can cause substantial distortion of the vision, with multiple images, streaking and sensitivity to light all often reported by the patient. Though frequently thought of as a rare condition, keratoconus is the most common dystrophy of the cornea, affecting around one person in a thousand, and it seems to occur equally in all ethnic groups worldwide. It is typically diagnosed in the patient’s adolescent years and attains its most severe state in the twenties and thirties.

Keratoconus is a little-understood disease with an uncertain cause, and the course of its progression following diagnosis is unpredictable. Deterioration in vision associated with the disease, if in both eyes, can affect the person’s ability to drive a car. It does not, however, lead to blindness, and in most cases, corrective lenses are effective enough to allow the patient to continue to drive legally and likewise function normally. Further progression of the disease may lead to a need for surgery. Keratoconus continues to be a somewhat mysterious disease, but it can be successfully managed with a variety of clinical and surgical techniques often with little or no impairment to the patient’s quality of life.


A simulation of the multiple images seen by a person with keratoconus. People with early keratoconus typically notice a minor blurring of their vision and come to their clinician seeking corrective lenses for reading or driving. At early stages, the symptoms of keratoconus may be no different from those of any other refractive defect of the eye. As the disease progresses, vision deteriorates, sometimes rapidly. Visual acuity becomes impaired at all distances, and night vision is often quite poor. Some individuals have vision in one eye that is markedly worse than that in the other eye. Some develop a sensitivity to bright lights, eye strain from squinting in order to read, or itching in the eye. Otherwise, there is little or no sensation of pain.

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The classic symptom of keratoconus is the perception of multiple ‘ghost’ images, known as monocular polyopia. This effect is most clearly seen with a high contrast field, such as a point of light on a dark background. Instead of seeing just one point, a person with keratoconus sees many images of the point, spread out in a chaotic pattern. This pattern does not typically change from day to day, but over time it often takes on new forms. Patients also commonly notice streaking and flaring distortion around light sources. Some even notice the images moving relative to one another in time with their heart beat.


Despite considerable research, the cause of keratoconus remains somewhat of a mystery. According to the United States National Keratoconus Foundation it is likely that keratoconus can arise from a number of different factors: genetic, environmental or cellular, any of which may form the trigger for the onset of the disease.


In early stages of keratoconus, spectacles can suffice to correct for the mild astigmatism. As the condition progresses, spectacles may fail to provide the patient with a satisfactory degree of visual acuity, and most clinical practitioners will move to managing the condition with contact lenses.

In keratoconic patients, contact lenses improve vision by means of tear fluid filling the gap between the irregular corneal surface and the smooth regular inner surface of the lens, thereby creating the effect of a smoother cornea. Many specialized types of contact lenses have been developed for keratoconus, and affected people may seek out both doctors specialized in conditions of the cornea, and contact-lens fitters who have experience managing patients with keratoconus.


The information presented here should not be interpreted as medical advice. If you need more information about Keratoconus, please consult a qualified physician or eye specialist.

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