How much of your child’s eyesight is genetic?

• Focusing errors of the eye (e.g. myopia) as well as eye turns (strabismus) require vision correction to avoid amblyopia (lazy eye).
• Colour vision deficiency is commonly inherited but usually does not get worse overtime.
• Several eye conditions of adulthood, such as age-related macular degeneration, can be more likely to develop when there is a positive family history.

“Both my husband and I wear glasses. Does that mean our child will have poor vision too?”

This is a common question among parents.

The answer is that it varies between eye conditions. Most eye conditions are not automatically inherited (passed down from your parents). However, having a close relative with a certain condition – such as a parent or sibling – can increase the risk of a child developing that condition.

Myopia (near-sightedness), hyperopia (far-sightedness), and astigmatism are different types of blurred vision that occur in people and are extremely common. These describe various kinds of focusing errors in the eye (refractive errors) due to differences in eye shape, resulting in blurry vision.

Myopia, hyperopia and astigmatism can have a genetic component.1-3

Out of the three, myopia is the one most widely observed to have a link between family history and a child’s vision development. For example, a child with one parent who is near-sighted is three times more likely to develop myopia themselves. The risk of developing myopia doubles again for families where both parents have myopia.4  Overall, genetics account for only a small proportion (around 10%) of the factors that go into determining whether a person develops refractive error.5  Most of that belongs to environmental and lifestyle factors, such as the time spent outdoors, screen time, and close work, which highly influence myopia development.6 

Most of the time, it is possible to prevent a high prescription from developing or worsening. This requires early detection during childhood by attending regular exams and having proper vision correction (e.g. glasses or contact lenses) to guide healthy development of vision.

Strabismus, commonly called a squint or eye turn, occurs when the two eyes do not point in the same direction at the same time.

Strabismus can have a hereditary component, meaning children with a family history may have a higher risk.7  However, it can occur for many different reasons and can develop at different stages of childhood.

When the eyes are misaligned, the brain receives two different images. To avoid seeing double, the brain may begin to ignore the image from one eye. Early assessment and treatment can help protect a child's visual development.8  This may involve prescribing special glasses, vision training, surgery, depending on how severe the eye turn is.

Red-green colour vision deficiency is the most common form of inherited colour vision deficiency. It is usually passed down through genes and is more common in boys than girls.9 

Colour vision deficiency usually does not reduce visual acuity, meaning that a child can still have clear vision. However, it may affect their ability to distinguish certain colours. This can become important in some school activities, hobbies and career choices.

Keratoconus is a condition in which the cornea, the clear front surface of the eye, gradually becomes thinner and more cone-shaped.

It is a complex eye condition with both genetic and environmental influences.10  Having a family history may increase the risk, but genetics alone does not determine whether a child will develop it. 

Eye rubbing is a major risk factor, as it causes physical damage to the cornea – which can either cause keratoconus to develop or cause it to get worse in individuals who are already affected. Hence, it is important to avoid eye rubbing and its triggers, including eye irritation, stress, and fatigue.

Signs and symptoms of keratoconus include:

• Blurred or distorted vision
• Increasing astigmatism
• Frequent changes in glasses prescription
• Difficulty achieving clear vision with ordinary glasses in more advanced cases

Stargardt disease, sometimes referred to as juvenile macular degeneration, is the most common childhood condition of the macula.11  The macula is the innermost part of the retina (back of the eye) responsible for detailed central vision.

Stargardt disease is an inherited condition, most often caused by inheriting a mutated ABCA4 gene from both parents (autosomal recessive inheritance). The condition leads to a buildup of waste products in the retina, which over time cause it to degenerate. Children with Stargardt disease experience gradual loss of central vision, which affects activities such as reading, recognising faces and seeing fine details.

Because inherited retinal diseases can have a significant impact on vision, children with a relevant family history or unexplained changes in vision may require further assessment by an eye care professional.

Family history is a risk factor for several eye diseases that develop later in life. One of the most well-known is age-related macular degeneration, where the risk of developing macular degeneration is significantly higher between relatives.12  Therefore, it may be important for affected individuals to advise close family members of their eye conditions so that their potential risk can be communicated to their respective doctor or optometrist.

Other eye conditions that may have genetic associations include:13 

• Age related macular degeneration
• Glaucoma
• Inherited retinal conditions, e.g. Retinitis pigmentosa , Stargardt disease
• Eye melanoma

If you are concerned whether your child may be at risk of developing a similar eye condition as you (or in general), the first point of call is to book a comprehensive eye examination. Regular eye examinations can help identify refractive errors, eye turns, and other eye conditions early, when appropriate management can make the biggest difference. In some scenarios when refractive errors and/or eye turns are left untreated, this can lead to the development of amblyopia (lazy eye), which has permanent effects on vision.

The first years of childhood are an important period for visual development, making it critical to spot and address any early signs of abnormalities. Many eye conditions develop gradually, which means that children and even some adults cannot tell when they are affected.