What happens in keratoconus ?The cornea is the clear window on the front of the eye. It is usually a regular spherical dome in shape. The substance of the cornea consists of hundreds of layers that are linked to each other by a substance called collagen. If these collagen cross-links between layers are lost due to keratoconus, there is a progressive corneal thinning and stretching which gradually progresses, often in both eyes. Normal pressure within the eye causes the cornea to bulge forward into an irregular cone shape. When light enters the eye, it first passes through the cornea. If the cornea has turned conical, there is distortion of the image. The eye develops astigmatism (cylindrical errors) and myopia (shortsightedness). This changes the eye sight power. In other words, the number of the eye changes. The glass power changes. This eyesight power change happens as and when the shape of the cornea changes. So in the intial stages the person complains of blurry vision. This blurry vision is corrected by a change of glasses and then the process repeats itself. In the later stages the central cornea can develop a scar which blocks light from entering the eye and this causes blurry vision. Patients may also complain of irritation and watering. In advanced stages the cornea may be significantly thinned out. It is not safe for someone to walk around with a very thin cornea. This thin cornea may rupture which may lead to loss of eyesight.
SYMPTOMS of keratoconus
- Early stages 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.
how is keratoconus diagnosed ?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. At our hospital, we use a very sensitive Pentacam Occulyser which records data from 25,000 points on the cornea.
Progress of the DiseaseKeratoconus is always, almost a progressive condition. In about 10% to 20% of patients, the keratoconus becomes very advanced. The cornea may become extremely steep, thin and irregular or the vision cannot be improved and also posing a risk of the transplant rejection.
Treatment of keratoconusKeratoconus is a known progressive disorder. All modalities of treatment whether it is glasses, contact lenses, INTACS or Phakic IOL’s, all correct the refractive error secondary to the cone formation; they DO NOT treat the keratoconus. Reason tells us that anything which is progressive first needs to be stopped and for that there is only one treatment that is available which is C3R or CXL. Talk to us today Corneal collagen crosslinking (C3R/ CXL) is a well-accepted and welcome addition to treatment options for keratoconus. Before C3R was approved, treatment options to rehabilitate vision were quite limited, mostly to contact lenses and when they failed one needed to undergo a corneal transplant.
Frequently Asked Questions
If left untreated, it can lead to sever vision loss.
Contact lenses will not help in reducing the progression of Keratoconus however patient with moderate to advanced case of keratoconus may not achieve great vision with spectacle due to irregular astigmatism and can achieve superior vision with specialized contact lenses.
As mentioned in above question, Vision can only be improved with contact lenses however to reduce the progression of keratoconus and to strengthen the cornea C3R surgery is required.