Corneal transplant

It also protects the iris and lens from external aggressions. It is a powerful refractive lens, allowing about two-thirds of the eye's adaptive ability to focus. Formed by three different layers separated by two membranes, it is the only organ in the body that lacks blood vessels that supply it, although it is highly innervated, that is, it has a multitude of nerve endings. It is nourished by tears and the aqueous humor of the eye.

How is it produced?

The cornea can suffer different alterations, such as trauma, chronic infections or alterations in the shape that reduce its transparency and consequently affect visual capacity. When this happens on many occasions the only possible solution is a keratoplasty or corneal transplant.

The cornea bases its refractive capacity on its transparency. If for any reason it is altered, visual capacity decreases. Here are cases where transparency can be affected:

• Recurrent infections such as keratitis, usually caused by bacteria or viruses, can cause corneal ulcers, so that the scar tissue that forms is somewhat more opaque than that of the original healthy cornea.
• Trauma or chemical burns can also make the cornea more opaque.
• Corneal dystrophies are a group of diseases that cause a loss of transparency of the cornea without any inflammatory process having taken place. They are alterations that affect both eyes, which usually appear in the first decades of life and progress slowly and progressively.
• Keratoconus is a progressive corneal degeneration in which the normal hemispherical structure of the cornea is transformed into a cone due to a thinning of the central area. It is usually bilateral but not symmetrical and makes vision increasingly blurry as it progresses.
• Age causes the cornea, like all tissue, to age and can degenerate in various ways, forming a peripheral arch (gerontoxon or senile arch) that does not affect visual capacity, or with a diffuse involvement of grayish specks that does not usually affect to vision, what is known as cornea farinata (mealy).

Symptoms

The loss of transparency of the cornea will essentially cause a lack of accommodation capacity and consequently a decrease in visual acuity, being able to see things blurred and distorted. In the case of trauma or some infectious corneal lesions, as in the case of herpes, there may also be ocular pain, lacrimation or purulent discharge.

Diagnosis

The diagnosis will be based on a correct ophthalmological examination in which the loss of transparency of the cornea will be observed, its possible lesions or alterations in shape and its thickness will be assessed.

Treatment

Initially, the lack of transparency of the cornea and its consequent, if they are slight, can be tried to alleviate with external measures such as glasses or contact lenses. However, if the injury progresses or causes great discomfort to the patient, occasionally a corneal transplant should be used. Corneal transplantation consists of replacing the damaged cornea with a corneal graft from a corneal donor. Transplantation makes it possible to reverse the visual alteration caused by the corneal pathology and to restore its normal structure and morphology if these are altered, as in the case of keratoconus.

Corneal transplantation is performed under local or rarely general anesthesia and is a procedure that usually takes less than an hour. Using special equipment, the ophthalmologist cuts the part of the cornea that is affected, removes and places a part of the donor cornea of ​​the same size. It is then sutured with a very fine thread that can only be seen at the microscopic level.

In the postoperative period, the eye should be protected, not touched or rubbed, and various antibiotic, anti-inflammatory and lubricating eye drops will be applied. After the intervention there may be discomfort. The recovery of vision is progressive but slow, it can take months to recover it, but a recovery of 90% to 100% of the visual capacity prior to corneal involvement is usually achieved. The stitches are not usually removed in their entirety until about eight months after the intervention.

Since the cornea does not have a blood supply, the risk of rejection is very low, with which the success of the transplant is usually assured. The possibility of rejection decreases progressively, being less than 10% after the first year of the intervention. In case of feeling pain in the transplanted eye, redness and decrease in it, it may be a rejection, which is why it is important to contact the ophthalmologist as soon as possible.

Transplant results will vary depending on the underlying corneal pathology. Corneal transplantation gives very good results in keratoconus, for example, or in single lesions, but when there are multiple lesions along the cornea the results are not so spectacular.

Precautionary measures

For certain pathologies that affect the cornea, such as keratoconus, corneal dystrophies or degenerations, there are no preventive measures. With regard to infections, you should always try to have correct eye hygiene and always protect your eyes when exposed to situations in which ocular trauma may occur. In the event of a corneal opacity, it is essential to put yourself in the hands of an ophthalmologist as soon as possible.

• The cornea is a half-sphere-shaped layer that lines the front of the eye.
• It is transparent and allows light to pass through it to the pupil and, from there, to the retina. The lack of transparency of the cornea means the loss of visual acuity and ability.
• The alteration of vision can be tried to alleviate with external measures such as glasses or contact lenses, but if the lesion progresses, a corneal transplant should be used.