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INHERITED EYE DISEASES: Many books have been written about Inherited Eye Diseases. It is impossible in one page to adequately deal with every facet of the subject. We will rather identify some of the more common conditions and inform you briefly about what they are, their method of inheritance, and what to do should one of the parents suffer from a potentially transmissible condition. It is important to identify these children early, to have them under the care of an ophthalmologist as soon as possible, to send them to the right schools if necessary, to start visual rehabilitation promptly, and to supply the parents with the relevant genetic counselling.
The disorders which can be passed from parent to child include chromosomal disorders of which Down (Down's) syndrome, also known as Mongolism, is probably the most well known. This condition is characterized by various ocular features, the most obvious being cataracts, corneal abnormalities and squint. Most Down syndrome cases arise from spontaneous mutations, but there are cases where one of the parents carries a defective gene. This can be determined by a genetic counselor.
Inborn errors of metabolism, or stated more simply, the absence or insuffiency in the body of a certain enzyme or enzymes, can manifest itself in many different forms depending on the resultant biochemical changes caused by the absence of the enzyme.
Diseases such as albinism, Gaucher's and Fabry's diseases, amyloidosis and Wilson's disease are all examples of metabolic conditions which can seriously affect the eyes and which can be inherited.
An infant can be born with congenital abnormalities of the eyes such as very small eyes, or an apparent absence of the eyes. Such events can occur with intrauterine infections such as German measles and certain parasitic infections which can be transmitted by cats.
Other anatomical deformities can occur, such as very small or very large corneas, and some infants are born with corneal opacities. The apparent total absence of the iris, implying that there is then no colored part of the eye, may be part of a syndrome where there is accompanying deafness and renal problems. There are numerous conditions which lead to infants being born with cataracts. The sight of these eyes can be greatly improved by cataract extraction and intra-ocular lens implantation, and the child needs to be under the care of an eye specialist as soon as possible to give the infant the maximum chance to develop optimal vision.
Many retinal disorders exist which can be inherited, and the more common ones include Retinitis Pigmentosa, color blindness, and some of the juvenile forms of macular degeneration. These are disorders of retinal function, involving degeneration of the retina.
Retinitis pigmentosa is an inherited condition which affects the retina. It is transmitted in different ways genetically from parent to child and usually presents with complaints of decreased night vision. It is a progressive disease, leading to eventual complete visual loss. There is a Retinitis Pigmentosa Association, and various support groups for patients with this condition.
The optic nerve can also be affected by inherited disorders, leading to optic nerve atrophy. Some maternal infections such as german measles may also lead to the optic nerve and the retina being damaged.
Other inherited disorders of the nerve may include abnormal shape and size.
Retinoblastoma is a malignant tumor of the retina which occurs in infancy and is sometimes inherited. Most are detectable within the first two years of life and may appear with a white, opaque pupil, or a squint. This is a potentially lethal condition and must be managed carefully by someone with experience in this field. This is why it is absolutely necessary for any child with a squint to be referred to and be examined by an ophthalmologist promptly.
The refraction with which the infant is born is usually inherited. A baby may be born with near-sightedness while another is born with far-sightedness. Being born with far-sightedness can contribute to the patient having a squint. This is yet another condition which can be inherited. The squint may be convergent or it may be divergent. One of our other Answers covers the topic of squints quite extensively.
As you can tell from the diseases listed here, there are a tremendous number of conditions which are potentially blinding which can be inherited. There are professional people available who are trained in genetic counselling who could assist with any queries you might have. If something is bothering you about your baby's vision, don't hesitate to take him or her to your ophthalmologist.
If you have any further questions regarding inherited eye conditions, please consult your eye specialist.