A coloboma represents a specific type of cleft formation on the eye. The cleft formation is either congenital or acquired in the course of life. In this case, the coloboma affects either the iris or the iris, the choroid or the eyelid of the eye.
What is a coloboma?
A coloboma is a cleft formation in the area of the eye. The term comes from the Greek for “mutilation.” The cleft formation either exists from birth or was acquired later due to various causes. In the majority of cases, the term coloboma is used in the field of ophthalmology. For this reason, the exact name for the disease is ocular coloboma. In principle, in some cases the coloboma is inherited, in others the cleft forms later. In a typical coloboma, the cleft appears in the form of a keyhole on the iris, more precisely on the so-called inferonasal underside. In addition to iris coloboma, there are also eyelid coloboma, papillary coloboma, lens coloboma, and a special coloboma at the back of the eye.
Causes
The potential causes of a coloboma differ primarily based on whether it is congenital or acquired. In the vast majority of cases of congenital coloboma, an error has occurred during embryonic development. During the development of the eye, a cleft occurs. This maldevelopment is counted among the so-called inhibition malformations. Due to faulty controls, the eye cup cleft does not close completely after the invagination (medical term “intussusception”) has been completed. Normally, the eye vesicle closes to form the so-called eye cup. In most cases, the eye cup slit points nasally downward in embryos. For this reason, congenital forms of iris coloboma often also point downward in a nasal direction. Depending on the individual cleft formation, one or more areas of the eye are affected by the malformation. The eye develops in the unborn child between the 4th and 15th week of pregnancy. If complete closure of the eye cup cleft does not occur during this time, a coloboma forms. The cleft formation affects either one eye or both eyes. In addition, in numerous cases, a coloboma occurs together with microphthalmia. This is an abnormally reduced eyeball. The malformation that ultimately leads to the development of a coloboma is in many cases triggered, for example, by drugs or other chemical substances. Especially the substance thalidomide has proven to be particularly dangerous in this context. In addition, there are some hereditary factors which, under certain circumstances, favor the formation of clefts in the eye. These include, for example, cat’s eye syndrome, trisomy 13, Charge syndrome, Cohen syndrome and Lenz syndrome. In addition, in some cases, cleft formation occurs as a spontaneous disturbance in the development of the eye. However, in numerous cases, the specific cause of congenital coloboma remains unclear. In some cases, for example, a mutation on the so-called Pax gene is responsible for the malformation of the eye. In this case, the inheritance is probably autosomal recessive, autosomal dominant or X-linked. For this reason, colobomas accumulate in certain families. In principle, however, the clefts appear rather sporadically, and various unexplained environmental conditions can be assumed to have an influence on the maldevelopment. Furthermore, in some cases coloboma is associated with various other diseases or syndromes. These include, for example, various neurological or systemic developmental malformations, such as Klinefelter syndrome, Noonan syndrome, Hirschsprung disease, and skeletal malformations. Congenital colobomas occur at an estimated frequency of 0.6 per 10,000 births. Consequently, it is a rather rare disease. Acquired colobomas, on the other hand, are in the majority of cases the result of external violence. Such effects are possible, for example, in connection with surgical interventions on the eye or accidents. As a result, the cleft forms on the iris, eyelid, or other areas of the eye.
Symptoms, complaints, and signs
If a coloboma is present, affected individuals suffer from various typical symptoms and complaints.Basically, vision depends on the severity of the cleft formation. Thus, completely asymptomatic colobomas are also conceivable. Many affected patients suffer from too bright light, because the regulatory ability of the iris is impaired. Large colobomas located on the optic nerve or retina may cause visual field loss (medical term “scotoma“) or blurred vision. Rarely, blindness results from the coloboma.
Diagnosis and disease progression
If individuals suffer from characteristic symptoms, an appropriate specialist should be consulted. Colobomas are usually relatively easy to diagnose because they have a typical appearance. After discussing the medical history, the attending physician performs clinical examinations of the eye and tests the patient’s vision.
Complications
Coloboma in most cases causes various discomforts or complications to the patient’s eyes. In the process, these discomforts can limit the daily life and living of the affected person and significantly reduce the quality of life. In the worst case, the affected person can go completely blind. The extent of the eye complaints, however, depends strongly on the size of the coloboma and its severity. In most cases, there is a strong incidence of bright light, so that the iris is damaged by this incidence. Similarly, there may be various paralyses and disturbances of sensibility in the face, which may also limit the daily life of the affected person. In this case, paralysis can become noticeable in the area of the mouth, so that the patient may be dependent on the help of other people in everyday life in order to be able to cope with it. However, life expectancy is reduced by a coloboma. In many cases, the loss of vision or complete blindness leads to depression and other psychological symptoms. Unfortunately, a coloboma cannot be treated. If it is a purely cosmetic complaint, the coloboma can also be removed. However, the paralysis in the visual field cannot be treated.
When should you see a doctor?
Individuals who experience decreased vision after surgery or after taking certain medications should consult their primary care physician. Individuals with cat’s eye syndrome, trisomy 13, and other inherited conditions are also at risk and should have close consultation with a medical professional. A visit to the doctor is necessary if the symptoms do not resolve on their own. If further symptoms such as visual field loss or eye pain develop, an ophthalmologist must be consulted. In case of complications such as blindness or paralysis of the mouth, the affected person is best taken to a hospital immediately. If there is acute danger of falling, the coloboma must be examined and treated. Since causal treatment is not possible, the patient must see a doctor regularly and adjust medication. In addition, an optometrist should be consulted. Suitable contact lenses can be used to correct the external blemishes. The vision itself cannot be treated therapeutically. Nevertheless, vision must be checked regularly so that any worsening of the coloboma can be detected early.
Treatment and therapy
Colobomas are not treatable and can only be cosmetically concealed by wearing appropriate contact lenses. Associated visual field loss also cannot be treated.
Outlook and prognosis
The prognosis of coloboma depends on the extent of damage sustained and therefore must be determined according to individual circumstances. First, it must be clarified whether the disorder is congenital or acquired. In the case of a congenital abnormality of the eye, surgical intervention is usually performed in the first weeks or months of life. Nevertheless, it is often not until the child’s further development that all symptoms can be fully elucidated. Naturally, an infant cannot fully respond to follow-up questions and tests. In the case of an acquired disorder in the course of life, a comprehensive diagnosis is easier and faster in most cases. The optical changes and abnormalities of the eye can only be changed by surgical intervention. Spontaneous healing is not to be expected with this disorder. Cosmetic surgery is associated with various risks and side effects.If an operation proceeds without further complications, an optimization of the cleft formation has normally taken place. However, impairments of vision suffered can rarely be fully regenerated. A large number of patients experience psychological states of distress due to the coloboma. In addition to mood swings and changes in personality, secondary diseases are possible. If depression is also diagnosed, this must be taken into account when making the overall prognosis.
Prevention
Because colobomas are congenital in most cases, no effective measures exist to prevent the malformation. If typical symptoms occur, a physician should be consulted.
Aftercare
Follow-up care is generally intended to prevent recurrence of disease. However, this does not apply to a coloboma. The congenital or acquired cleft formation of the eye is permanent. Patients must live with the typical symptoms such as visual field loss. They cannot be corrected. However, aftercare can provide aids of various kinds. Some people suffer from psychological problems due to the disease, for example. Impaired vision can also cloud the meaning of life. With therapy, doctors can support those affected in their everyday lives and show them private and professional opportunities. The cosmetic problem can still be remedied by special contact lenses and glasses. This reduces elementary complications to a minimum. Ophthalmologists recommend regular control of the affected eyes. In this way, secondary diseases can be addressed at an early stage. A rhythm is agreed upon individually. This is because the iris can suffer further damage due to the incidence of light. As a consequence, blindness, retinal detachment or glaucoma is then possible. Furthermore, paralysis of the face has been demonstrated in certain individuals. Aftercare thus aims at stabilizing the disease – without, however, being able to address the actual cause. It is a matter of permanent everyday assistance, through which patients realize a wide measure of independence.
What you can do yourself
Patients with coloboma of the eye suffer from physical as well as mental and cosmetic discomfort. The gap formation in the area of the iris, which is typical for coloboma, is also noticed by fellow people and therefore often leads to insecurity or even inferiority complexes in the patients. These reduce the quality of life of those affected and, in the worst case, lead to depression. If people with coloboma increasingly suffer from psychological problems due to the visual conspicuity, they seek the help of a psychotherapist in their own interest. In order to conceal the gap in the eye, special contact lenses can be used, which at least optically cover the coloboma and thus make it invisible to other people. With regard to the physical complaints, it is above all glaring light that causes the patients problems. In order to improve their quality of life, patients are recommended to wear special glasses on a regular basis. Conventional sunglasses with darkened lenses can be used to reduce glare. Special glasses that adjust their lens color to the brightness of the surrounding light are also possible and are a good choice for many sufferers. In severe cases, coloboma results in visual field loss and blindness, which patients come to terms with through appropriate measures such as caregiver services.
