Some vision problems are genetic, but others are influenced by the environment and your lifestyle. Thick curly hair, a distinct nose shape, disarming blue eyes – these are some of the things that run in families. Unfortunately, so do nearsightedness and far-sightedness. But not all eye problems are genetic; they may be caused by environmental issues too. Healthy living is an integral part of maintaining a healthy vision as you age. The healthier you are, the better chance you have of avoiding damage to your eyesight.
Understanding how genes, environmental issues and lifestyle habits can affect your eye health.
Many of the leading causes of blindness are linked to genetic factors, according to Dr Yolandie Coetzee from Envison Sight. Inherited eye diseases cause more than 60% of blindness in infants. These include:
- Congenital cataracts
- Congenital glaucoma
- Retinal degeneration
- Optic atrophy
- Eye malfunctions
- Fundus dystrophies (a condition characterised by the loss of central vision)
- Near-sightedness and farsightedness
However, she points out that it is almost impossible to determine whether genetics or environmental factors are to blame for eye disorders as the issue is so complex.
“In adults, diseases like glaucoma and age-related macular degeneration – both of which are leading causes of blindness – can be the result of a mix of genetic and environmental factors. Diabetes – which may be caused by a combination of genetic makeup, family history, health and environmental factors, such as lifestyle – is a leading cause of eye diseases including diabetic retinopathy, diabetic macular oedema (DME), cataracts, and glaucoma.” Click here to discover the aging process of the eyes – and how you can slow it down.
How will your family’s eyesight history affect your children?
If you’re curious about your family’s vision history and how it might affect your children, it’s advisable to see an eye doctor. “You can also look at the prevalence of eye disease in your family,” says Coetzee. “Genes for certain diseases have been extensively mapped to gene testing and would be a great predictor of a condition such as inherited retinal disease.” Researchers have mapped several genetic risk factors for glaucoma.
Genetics
These genes were found by genetically sequencing the DNA of families with the genetic condition. “It’s extremely complex and is based on finding the same needle in several haystacks,” Coetzee explains. “To make it even more complex, the penetrance (the extent to which a particular gene or set of genes is expressed in the phenotypes of individuals carrying it) may vary. This means that you will not necessarily have the disease even if you have the gene. According to a US study on glaucoma, genetic testing can be a powerful tool in specific diseases like familial juvenile open-angle glaucoma, where care can be better optimized.
There are approximately 250 genes that cause inherited retinal diseases. In South Africa, myopia, glaucoma, acture macular degeneration, and diabetes are the leading causes of vision loss. They all have a large genetic component, according to Coetzee. “Although not much can be done to prevent the inheritance of a gene, research in the field of gene therapy has exploded in the last 15 years.
The human retina is ideal for the assessment of gene and cell therapies because of its accessibility for monitoring, imaging, and surgical manipulation.” Luxturna, a one-time gene therapy treatment, was approved y the US Food and Drug Administration on 19 December 2017. This is used to improve vision in patients with genetic vision loss due to Leber congenital amaurosis or retinitis pigmentosa, both of which are retinal dystrophies. Clinical trials involving retinal gene therapy are creating hope for future therapies for other retinal diseases.
How diet, lifestyle, and environment may affect eye health
Although poor eyesight is often hereditary, the number of people with nearsightedness – which has a strong genetic component – has almost doubled in the past decade. Coetzee says that time spent in front of computers and cellphones could be significant contributing factors to eye issues such as nearsightedness.
“According to a few epidemiology studies, spending time outdoors in early childhood also reduces the onset of myopia, or nearsightedness, which has become more prevalent in recent years. This is just one example of how lifestyle rather than genetics may affect your eye health.”
Coetzee advises that, in general, a healthy lifestyle is important for maintaining good eyesight. “A poor diet, smoking, and unhealthy BMI (body mass index) may increase your chances of developing age-related macular degeneration. That’s why it is important to follow a healthy diet and manage body weight, not smoke, and exercise regularly.
For patients with glaucoma, a vegan diet and regular exercise can also help lower the pressure on the eyes. The antioxidants found in fruits and vegetables can help reduce vision loss related to aging. It’s also important to take preventative action. This can include protecting your eyes from the sun’s UV rays to avoid the development of cataracts.”
How else can you prevent eye disease?
- Find out whether your medical aid offers genetic testing.
- Have regular eye exams to look for changes in blood vessels or retina that indicate diabetic retinopathy.
- Have your eyes tested routinely. In this way, you can prevent yourself from having more future problems.
