KERATOCONUS (cone shaped cornea)
What is keratoconus?
Keratoconus is a common bilateral corneal condition, occurring in more than 1 in 1000 people. The condition typically starts in adolescence and early adulthood.
Keratoconus is a disease with an uncertain cause, and its progression following diagnosis is unpredictable. If afflicting both eyes, the deterioration in vision can affect the patient’s ability to drive a car or read normal print. Further progression of the disease may lead to a need for surgery.
Despite its uncertainties, keratoconus can be successfully managed with a variety of clinical and surgical techniques, and often with little or no impairment to the patient’s quality of life.
At early stages, the symptoms of keratoconus may be no different from just having the need for spectacle correction. As the disease progresses, the vision deteriorates. Visual acuity becomes impaired at all distances, and night vision is sometimes quite poor. Some individuals have vision in one eye that is markedly worse than that in the other eye. Some develop photophobia (sensitivity to bright light), eye strain from squinting in order to read, or itching in the eye. There is usually little or no sensation of pain. Keratoconus can cause substantial distortion of vision, with multiple images, streaking and sensitivity to light.
This is usually done by an ophthalmologist with a detailed eye examination. Diagnosing early keratoconus can be tricky, since mild disease often does not show any identifiable signs on slit-lamp examination; however, recent and a more definitive diagnosis can be obtained using corneal topography, in which an automated instrument projects an illuminated pattern onto the cornea and determines its shape from analysis of a digital image. The topographical map reveals distortions or scarring in the cornea, with keratoconus revealed by a characteristic steepness of curvature which is usually below or around the centre of the cornea. The topography record of the degree and extent of the deformation is used for assessing its rate of progression. Unilateral cases tend to be uncommon. Sometimes it’s a mild condition in the better eye, below the limit of clinical detection. It is common for keratoconus to be diagnosed first in one eye and not until later in the other.
Treatment of mild keratoconus is geared towards eliminating or reducing the myopia and astigmatism.
- Contact Lenses
New modality of treatment:
- Corneal Collagen Crosslinking with Riboflavin (C3-R®*)
Initial management is tried with rigid contact lenses by our contact lens specialist. In very early stages of keratoconus, spectacles can suffice to correct minor astigmatism. As the condition progresses, spectacles may no longer provide the patient with a satisfactory degree of visual acuity, and most doctors will move to managing the condition with contact lenses.
Rigid gas permeable contact lenses for keratoconus improve vision by means of tear fluid filling the gap between the irregular corneal surface and the smooth regular inner surface of the contact lens, thereby creating the effect of a smoother cornea.
Many specialized types of contact lenses have been developed for keratoconus, and our contact lens expert helps you with the best fit. The irregular cone needs expertise to produce a contact lens with optimal contact, stability and steepness. Some trial-and-error fitting might be necessary.
Traditionally, contact lenses for keratoconus have been the ‘hard’ or rigid gas-permeable variety, although manufacturers have also produced specialized ‘soft’ or hydrophilic contact lenses. A soft contact lens has a tendency to conform to the conical shape of the cornea, thus diminishing its effect. These do not however prove effective for every patient.
Some patients also find good vision correction and comfort with a “piggyback” contact lens combination, in which gas permeable rigid contact lenses are worn over soft contact lenses, providing clarity of vision and comfort.
Precaution with contact lenses: There is a small risk of infection when wearing contact lenses and the risk becomes much greater if the contact lenses are not kept clean, so it is important to strictly follow the hygiene instructions given when the contact lenses are fitted.