The human eye is made up of several layers. Each layer has a different morphological makeup designed according to the functions. Any disease affecting even a single layer of the eye, alter the complete functionality of the eye, causing loss of eyesight and other related conditions.
The eye has one such essential component; it is the transparent window at the front of the eye called cornea. It is a round shaped membrane. The case where the cornea becomes thinner and bulges outwards in a cone shape is known as keratoconus.
It is a progressive condition getting worsened gradually over time. The progression and severity of the disease are different for different people. This disease affects two-thirds of the eye’s focusing ability. It is also considered one of the major causes of visual impairment.
This disease leads to thinning of the stroma layer with consequent forward bulging into a conical shape due to structural weakness. It leads to high levels of astigmatism, combines with myopia. Due to the progressive distortion of the cornea front surface, it’s challenging to correct the vision with specs or contact lenses. Hence it’s essential to diagnose this disease in the early stages only to prevent further damage to the cornea.
How Does It Affect The Vision of an Individual?
The patient’s vision becomes blurred as the front of the eye is not evenly smooth and round. It affects the focus of the eye affecting on short sight causing myopia and astigmatism in which light passes through the eye creating an unclear image at the back of the eye.
Lafayette Optometrist, Dr. Durocher, tells us that in advanced stages of the disease, patients develop scarring in the cornea thus affecting their sight by reducing the amount of light entering the eye. Some patients also experience sudden painful loss of vision when the fluid from the eye flows into the cornea.
Cause of Keratoconus
Exact etiology is unknown, but genetic factors are taken into consideration. Patients suffering from eczema or asthma are prone to this condition.
Different Morphological Patterns of the Affected Cornea
The corneal topography determines the morphology of the cone.
- Nipple cones: They are characterized by a small shape and a steep curvature. The apical center is mostly central or paracentral and commonly displaced.
- Oval cones: They are of larger diameter, ellipsoid in shape and unevenly displaced
- Globus cones: They are most significant and cover 75% of the cornea. They have a tangential curvature.
The treatment option depends on the stage of the disease and its severity.
- Spectacles or Contact Lenses: spectacles and soft contact lenses may be used for correcting the disease at early stages. As the disease progresses and cornea bulges forward, hard contact lenses are the long-term option. Further deterioration of the disorders will eliminate this possibility also due to the abnormal shape of the cornea.
- Corneal Cross-Linking: the plan is to stabilize the cornea to prevent further deterioration. For the treatment, the cornea has to be 400 microns thick to apply this treatment safely. This procedure strengths the links between the collagen fibers of the cornea, thus reinforcing the structure of the cornea. For this treatment, the superficial layer of the cornea is removed, followed by riboflavin application at regular intervals till saturation of the corneal stroma with vitamins. UV radiation is applied to the cornea to strengthen the chemical bond between the adjacent stromal fibers, forming linkages. The riboflavin vitamin acts as a catalyst for stimulating the cornea fibers to form bonds. After initiation, the bond forming process continues for 6-24 months.
- Intracorneal ring segments(ICRS): they comprise of thin, transparent, ultra-thin precision made crescents (the same material that is used to make contact lenses). They are inserted and implanted in the stroma, enabling the bending of the cornea into a regular shape. It comes to use in early phases of keratoconus.
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- Corneal implants: as this is an invasive and expensive procedure, is recommended in the advanced stages, also due to its more extended recovery period. In this process, the damaged corneal tissue is removed, replaced with a dense tissue from the human donor. These implants are carried out and inserted in 3 different methods mostly; Penetrating keratoplasty, Lamellar corneal transplant, and Mushroom transplant.
- Penetrating keratoplasty: It is the process where the donor tissue does the complete transplant of the central cornea. It is the most convenient method for the corneal transplant.
- Lamellar corneal transplant: Only the affected corneal layer is removed and replaced with the similar section of the donor tissue. It is not used in every case as the part varies.
- Mushroom transplant: This method combines larger diameter superficial layer of tissue with the smaller diameter central layer looking like a mushroom.
Our eyes help us see the world around us. Taking good care of it is absolutely vital. If you are suffering from Keratoconus, visit an optometrist for professional advice today.