The cornea is front clear part of the eye in front of the color (or iris) of the eye. In ideal circumstances the cornea is round much like the shape of a soccer ball. The cornea is a clear structure to permit sharp unobstructed vision. If the shape of the cornea is not round or irregular, vision is compromised. In astigmatism the shape of the cornea simulates that of a rugby ball. Astigmatism is a spectacle error, just like nearsightedness (myopia) and farsightedness (hyperopia), which necessitates the use of spectacles or contact lenses to correct vision.
The shape of the cornea is accurately evaluated in the practice with the use of the Penatacam. This appliance accurately takes thousands of measurements of the cornea to compare it with normal. The newest software in the form of the Bellin-Ambrosio ectasia indicators are used to diagnose keratoconus and also to evaluate any changes that occurs over time indicating progression.
The cornea is approximately 550 micrometers thick, but in keratoconus there is abnormal thinning of the cornea with subsequent bulging like a cone. The condition typically starts in puberty and gradually deteriorates. Only one eye is initially affected, but within a few years the other eye will also show signs of weakness. The thinning of the cornea leads to changes in the shape of the cornea resulting in a spectacle error, but due to the progressive thinning the cornea becomes irregular. This irregular shape means that the patients’ vision cannot be corrected with spectacles. Rigid contact lenses are then used to smooth the front surface of the eye and improve vision.
Due to the progressive nature of keratoconus, the patient will gradually become more dependent on spectacles, but sometimes the vision can also suddenly deteriorate with poor vision despite the use of spectacles. Corneal collagen cross-linking is a new treatment aimed at strengthening the cornea, preventing further weakening and preserving a patients’ vision. Therefore it is essential to perform cross-linking as soon as possible when the diagnosis of keratoconus is made. Contact us for more information on keratoconus and its treatment options
If cross-linking is not performed, the corneal thinning progress even further and then even rigid contact lenses cannot correct the patients’ vision. Corneal graft surgery is the final attempt at restoring vision. The central weak bulging cornea is replaced with donor tissue of normal strength and thickness. The success of surgery is very good, but the visual improvement does take quite long to achieve due to the fact that the cornea has to heal before the sutures can be removed. The aim of surgery is to replace the central thin cornea with a clear cornea, but the patient is still left with a spectacle error after surgery. There is different ways to correct this: spectacles, contact lenses or surgery can be used. Laser eye surgery is very effective in correcting the spectacle error and restoring vision.