Coloboma on the eye
A coloboma in the general sense is when there is a gap in the eye. The iris (rainbow skin) is most often affected. If you look closely into the eye, you can see a “keyhole-shaped” pupil in the affected person. So you have the round pupil and also a dark slit through which you can also look into the eye. At this point the iris has not completely closed. Other structures of the eye can also be affected less frequently. This can lead to a coloboma on the lid and lens. The back of the eye (fundus and papilla = place where the optic nerve enters) can also be affected.
What are the causes of a coloboma?
In most cases, a coloboma of the eye is congenital. This leads to an error in the development of the eye in the embryonic phase. Mutations in different genes often play a role. Environmental factors are less involved. They are of particular importance in the 4th to 15th week of pregnancy, as the structure of the eye develops during this time. If there are strong external influences during this phase, this can disrupt the development of the eye. Basically, a coloboma can be present in either one or both eyes. It is not possible to differentiate precisely which causes play a role in bilateral and which in unilateral development of the coloboma.
Furthermore, the development of a coloboma in the eye is associated with other malformations and diseases. Often there are malformations of the face and skull as part of syndromes, and the eye can also be affected. Hereditary diseases that can trigger a coloboma in the eye are, for example, trisomies, in which a chromosome (structure on which part of the human genome is stored) is present in three (instead of the usual two) versions. The most famous trisomy is trisomy 21 (also called Down syndrome). However, other genetic diseases such as the CHARGE association or DiGeorge syndrome can lead to colobomas in the eye, along with other malformations.
Basically, a coloboma in the eye can only develop in the course of life.Typically, this can occur after eye injuries or surgery that do not fully heal. Such a coloboma is usually only present on one side.
How is a coloboma diagnosed?
The diagnosis of coloboma in the eye is usually a so-called eye diagnosis. With the practiced eye of the examiner, the formation of gaps in the affected eye sections is noticeable. If the iris is affected, the coloboma can be recognized very easily. In order to be able to make an accurate estimate of which parts of the eye are affected, further examinations can be carried out. For example, the slit lamp examination is used to assess the anterior parts of the eye. To look at the fundus, on the other hand, a so-called funduscopy is best suited.
What are the accompanying symptoms?
The symptoms that are associated with coloboma of the eye are typically very dependent on the cause of the disease. During eye operations, pain and swelling of the affected eye can occur in the first few days. The operation can also affect eyesight. In the case of injuries to the eye, pain also occurs primarily. Depending on which parts of the eye are affected by the injury, it can lead to impaired vision or eye movement. If the eyelid is also injured, the eye may not be able to close completely, causing it to dry out.
In the case of congenital colobomas of the eye, accompanying symptoms can also occur. If, for example, structures in the back of the eye are affected, the light falling into the eye may be impaired so that the person's field of vision is restricted. If there are malformations of the anterior segment of the eye, this usually causes problems with the refraction of the incident light. For example, a pupil that is dilated by a coloboma cannot be regulated so well, so that the eye can only adjust to different levels of brightness with difficulty. If, on the other hand, the lens is affected, it may not be possible to see clearly with the affected eye. In the case of a lid coloboma, the eyelid is affected by the gap formation. This can lead to the eye becoming more dehydrated because it cannot be closed completely.
How is a coloboma treated?
The therapy of coloboma depends on the underlying cause and is also based on which structures are affected. The most common variant is the formation of a gap on the iris. If this occurs without other structures being affected, the disease often does not need to be treated. If, on the other hand, there are disorders in the functional line of sight of the eye (for example on the lens or the retina), therapy is often useful to improve the vision of the affected eye. However, an exact treatment regimen is complex and must be created very individually depending on the underlying disease and the resulting malformation.
On the other hand, the treatment of acquired coloboma in the eye is clearer. This is caused by operations and injuries. Ideally, during operations it is important to avoid the development of colobomas, as this leads to impaired vision. If the coloboma occurs in the eye, the treatment is similar to that of a coloboma after an injury. In the event of an injury, an attempt is made to sew the injured structures back together by means of the smallest surgical interventions on the eye. If this does not succeed, some structures of the eye can be artificially replaced. This applies to the lens of the eye, for example. This is particularly important for sharp vision. If the lens function is disturbed due to the coloboma, an artificial lens can be inserted into the affected eye, for example.
How long does a coloboma on the eye last?
With congenital colobomas, the duration of a coloboma of the eye can usually be expected for life. In the case of non-limiting colobomas, therapy is also not sought. If the eyesight is reduced due to the coloboma, it can be treated with an operation, but mostly residues of the congenital coloboma remain.
Acquired colobomas of the eye, on the other hand, can heal on their own from very minor injuries. Areas with particularly good blood circulation, such as the eyelid, grow together well. Other structures in the eye, on the other hand, have to be treated surgically. Depending on how fast the healing progresses, restrictions of a few weeks can be expected. If there are scars in the optical axis (i.e. the area through which the light falls into the eye), there can also be permanent impairment of the eyesight of the affected eye.
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