While first credited to Sir Francis Galton in 1869, the debate between nature and nurture has been raging on since 400 BCE with Hippocrates and his contemporaries. It is undeniable that we inherit physical and biological qualities from our predecessors and pass them down to our descendants.
But just how much and what exactly? This question has fascinated me for a long time, especially when it comes to our eyes. The philosopher in me is eager to begin a controversial argument. But science is never a debate. It is a conglomeration of facts. Hence, my inner clinician must delve into the known issues.
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Today, myopia affects 65 per cent of children aged 12 years and below and 83 per cent of young adults in Singapore. By 2050, up to 90 per cent of Singaporeans will be myopic by the time they turn 18. As children spend less time outdoors, there’s no denying that our highly built-up and humid country with less wide-open spaces, coupled with our exam-oriented culture, has led to this increase.
We also know that parents with myopia will most likely have myopic children. Genetic linkage studies have reported myopia heritability ranging between 70 and 95 per cent. The retina, which houses all the photoreceptors responsible for our vision, is arguably the single most important structure in our eye. Retinal tears and detachment, which come about because of breaks in the inner wall of our eyeball, happen because of inherent areas of weakness.
Although these weak areas are often a result of myopic elongation of the eyeball, clinicians have noted that retinal weakness can also occur in the absence of myopia and within members of certain families. Glaucoma, also known as the silent thief of sight, is a progressive neurodegenerative disease of the optic nerve that frequently causes irreversible vision loss before you are even aware of its existence. Genetic studies have suggested that over 50 per cent of glaucoma is familial and the risk of getting it is approximately 10 times higher in those with a sibling who has glaucoma.
What’s more, at least 15 per cent of patients have at least one sibling who has glaucoma. Cataracts, traditionally thought of as an age-related degenerative condition, can also be hereditary. Just recently, I treated a patient who had an asymmetrically dense white cataract in one eye at the early age of 40.
While searching for the aetiology of this early-onset cataract, I found that his father and sister had early-onset unilateral cataracts at an early age as well, likely attributed to a familial trait. With myopia, retinal detachment, glaucoma and cataracts, just to name a few, being genetically linked, I recommend having your eyes checked at regular intervals for early detection and prevention.
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You can bring the entire family down for a screening session with your eye specialist and make it a fun day out. Prioritising the eyes and vision of you and your family can be one of the best things you can do for yourself and them.
Dr Claudine Pang is the medical director of Asia Retina Eye Surgery Centre and the founder of Eye Quotient and Eye Care Without Borders.