Inherited eye Diseases: An overview
As the understanding, knowledge and research about the health and diseases are increasing in general, both the ophthalmologists and the patients are increasingly facing the challenge of Inherited eye Diseases. Hence, there is both an increasing incidence of the inherited eye conditions and need to understand about these. This article looks at some of the common and interesting aspects about the Inherited Eye Diseases.
What is an Inherited Eye Disease?
An ‘Inherited Eye Disease’ or ‘Hereditable Eye Disease’ is a condition which has the potential to be transmitted from one generation to the next. Thus, there is a chance for the disease to run in the generations. Such diseases are usually caused by the defect in our ‘Genes’ which are like the programme code for the way the how our body develops, appears and functions. Such diseases vary from some of the other diseases like infections because they are not caused by the outside factors but by something inside our bodies.
What are the common Inherited Eye Diseases?
Examples of common inherited diseases of the eye are congenital cataract, congenital glaucoma, retinaldegeneration (such as retinitis pigmentosa, Stargardt’s disease), optic atrophy, eye malformations such as microphthalmos (small eyeball), anophthalmos (missing eyeball), cancers of the eye such as Retinoblastoma, etc.
Incidence and Relation to the Other Body Diseases?
Due to increased reporting the incidence of the diseases is increasing worldwide. It is believed that the inherited eye diseases can account for about 50% of the causes of the childhood blindness..
These diseases may not able be limited to the eye but may also be either a part of the whole body abnormality (an association) or may be associated with multiple eye and body defects (syndrome).
Inherited Eye Disease and Risk of Disease in the Relatives:
As soon as the doctor makes the diagnosis of an inherited eye disease, it raises doubts in the minds of the doctors, patients and the relatives. This brings a lot of apprehension and concern in the family. However, we need to understand a little bit more about the same.
To simplify, we can assume the entire programming for the entire body is done in the form of genetic material which is organised in the form of the chromosomes which are present in the each cell. There are 23 pairs of the chromosomes: 22 (Chromosomes 1-22) of which decide the body functions and 1 pair which decide the gender of the person (X and Y). The genetic material on the chromosomes is coded in the form of the genes which is made up of the sequence of biomolecules called as ‘Nucleotides’. Some more amount of the genetic material is present in organelles which are present in the cytoplasm of the eye, called mitochondria. Any change in this genetic material either is called as ‘Mutation’.
The inherited eye disease can result from:
Chromosomal abnormalities which are defects in the chromosomes such as an increased/ decreased number of chromosomes (e.g. Trisomy 21 which causes Down’s Syndrome)
Mutations which do not affect the whole chromosomes but affect the particular genes which are just a part of one of the chromosome (such as aniridia).
Management of the Hereditable Eye Diseases:
Since the hereditable eye diseases have a genetic basis and is manifest in the given patient, the physician role is to try and minimise the effects of the complications resulting from these. In addition, a detailed body examination is necessary and many times we need to consult with other colleagues in various fields to detect the associated body conditions and treat them. Thus children with genetic eye conditions need to be managed as a whole taking care of the entire body needs.
Progress in the Management of the Inherited Eye Disorders:
There is a wide interest in the field of the ophthalmic genetics and at the same time, there is a limited success in the management of some of the inherited eye conditions. Management of the specific conditions requires an in-depth analysis of the family history, laboratory testing to analyse blood samples and specific testing to locate the disease.
There is an increasing awareness amongst the patients and their relatives and healthcare physicians alike. In the wake of the increased knowledge, understanding, systemic manifestations of the inherited eye diseases, there is every hope that these can be identified early on now. Many of the eye care centres have been able to identify and form a liaison with the physicians, paediatricians and geneticists to take holistic care of these patients as a whole. Although at this time the best approach seems to be prevention of the diseases in the future generations by appropriate counselling, we may see the advent of genetic therapy for some of these conditions in the years to come. It is therefore best for parents to be aware of the various inheritable eye disorders.