Myopia

Myopia, commonly known as nearsightedness or shortsightedness, is a refractive error in which distant objects appear blurred while close-up objects remain clear. It occurs when the eyeball grows slightly too long from front to back, or when the cornea is too steeply curved, causing light entering the eye to focus in front of the retina instead of directly on it.

Myopia is an especially significant eye health issue in Singapore, where it is far more prevalent than in most other parts of the world. Studies show that more than 80% of adult Singaporeans are myopic, and myopia now affects a large and growing proportion of children as well, often starting well before their teenage years. This makes understanding, monitoring and managing myopia — particularly in children — a genuine public health priority, not just a matter of eyeglass prescriptions.

Degrees of Myopia

Myopia is measured in dioptres (D), a unit describing the strength of lens correction needed, and is generally classified by severity. Understanding your degree of myopia helps guide both your correction options and your long-term eye health monitoring.

Low Myopia (up to -3.00D): The most common category, typically well corrected with glasses or contact lenses. Long-term eye health risks are only mildly elevated compared to someone without myopia.
Moderate Myopia (-3.00D to -6.00D): Distance vision is significantly blurred without correction. Long-term risk of certain eye conditions begins to rise more noticeably at this level, making regular eye examinations more important.
High Myopia (greater than -6.00D): Associated with significant elongation of the eyeball, and a considerably higher lifetime risk of retinal detachment, myopic macular degeneration, glaucoma and early cataract. Regular dilated eye examinations are strongly recommended.
Pathologic (Degenerative) Myopia: A more severe subtype, usually associated with very high myopia, in which progressive stretching and thinning of the retina and underlying eye tissue can lead to structural changes and vision loss even in adulthood, independent of further glasses prescription changes.

What causes Myopia?

Myopia develops when the shape of the eye causes light to focus in front of the retina rather than directly on it, producing blurred distance vision. Two related mechanisms are usually involved:

Axial elongation: In most cases, the eyeball itself grows slightly too long from front to back during childhood and adolescence — the single most important factor driving both the onset and progression of myopia.
Excessive corneal curvature: Less commonly, the cornea (the clear front surface of the eye) is more steeply curved than average, bending light more strongly than needed and causing a similar focusing error.

The exact cause of myopia is not fully understood, but current evidence points to a combination of genetic and environmental factors working together:

Genetics: Children with one myopic parent have a higher risk of developing myopia, and the risk rises further with two myopic parents — suggesting a strong hereditary component.
Near work: Extended periods of close-up visual tasks — reading, writing, and particularly smartphone and tablet use — are strongly linked to both the development and progression of myopia in children.
Limited outdoor time: Numerous studies have found that children who spend more time outdoors in natural light have a lower risk of developing myopia, independent of how much near work they do — thought to be related to light exposure and its effect on eye growth.
Onset in childhood: Myopia typically first appears between ages 6 and 12 and tends to progress throughout childhood and adolescence as the eye continues to grow, usually stabilising in early adulthood.
Adult-onset myopia: Less commonly, myopia can develop or worsen in adulthood, usually to a low or moderate degree, often associated with intense near-work occupations or prolonged close-range screen use.

Symptoms of Myopia

Myopia often develops gradually, particularly in children, which means the signs can be easy to miss until vision is significantly affected. Common symptoms include:

Blurred vision when looking at distant objects, such as road signs, whiteboards or television
Squinting or partially closing the eyes to try to see more clearly
Frequent eye strain, eye fatigue, or rubbing of the eyes
Headaches, particularly after visually demanding tasks
Sitting unusually close to the television, or holding books, phones or tablets very close to the face
In children: difficulty seeing the whiteboard at school, reduced interest in distance-vision activities such as sports, or unexplained declining academic performance
Squeezing the eyes shut briefly to bring distant objects into sharper focus

Because young children may not recognise or report blurred vision — believing it is simply how everyone sees — regular vision screening is important even in the absence of obvious complaints, particularly during the school-age years when myopia most commonly develops and progresses.

Risk Factors for Myopia

While myopia cannot always be predicted with certainty, several factors are known to increase the likelihood of developing it or of it progressing more quickly:

Family history: Having one or both parents with myopia significantly increases a child's risk of developing the condition.
Ethnicity: Myopia is markedly more common among East Asian populations, including in Singapore, compared to other parts of the world, suggesting a genetic predisposition alongside environmental influences.
Extensive near work: Prolonged reading, studying, or use of smartphones, tablets and computers at close range, especially without regular breaks.
Limited time outdoors: Children who spend little time outdoors — a common pattern in dense urban environments and among children with heavy academic schedules — are at higher risk.
Early age of onset: Children who become myopic at a younger age tend to reach higher degrees of myopia by adulthood, as there are more years of eye growth remaining for the condition to progress.
Urban living: Higher rates of myopia are consistently observed in urban, densely populated settings compared to rural areas, likely reflecting a combination of more near work and less outdoor time.

Complications of High Myopia

Retinal detachment: An elongated eyeball stretches and thins the retina, making it more prone to tears and detachment — a sight-threatening emergency that becomes significantly more likely with high myopia.
Myopic macular degeneration: Progressive thinning and structural change in the macula (the central part of the retina responsible for sharp vision), which can lead to permanent central vision loss in severe cases.
Glaucoma: People with myopia, particularly high myopia, have a higher risk of developing glaucoma, a condition involving progressive damage to the optic nerve that can lead to irreversible vision loss if undetected.
Early cataract: Myopic individuals tend to develop cataracts — clouding of the eye's natural lens — at a younger age than the general population.
Myopic choroidal neovascularisation: A less common but serious complication in which abnormal blood vessels grow beneath the retina, which can cause sudden distortion or loss of central vision and requires prompt treatment.

These risks rise progressively with the degree of myopia, which is why controlling myopia progression in childhood, rather than simply correcting vision as it worsens, has become such an important focus of modern eye care.

How Myopia Is Diagnosed

Myopia is diagnosed through a comprehensive eye examination, which is straightforward, painless, and suitable for both children and adults.

Visual Acuity Test: Reading letters of decreasing size on an eye chart to measure how clearly you can see at various distances, forming the initial assessment of any refractive error.
Retinoscopy: A handheld lighted instrument (retinoscope) is used to observe how light reflects off the retina, allowing the examiner to estimate the eye's refractive error, which is especially useful in young children.
Refraction Test: Using a phoropter or trial lenses, the examiner fine-tunes the exact lens power needed to bring vision into sharp focus, determining the precise glasses or contact lens prescription.
Axial Length Measurement: A quick, non-invasive scan measuring the length of the eyeball from front to back, used to track how much the eye is elongating over time — particularly important for monitoring myopia progression in children.
Dilated Eye Examination: Eye drops are used to widen the pupil, allowing the ophthalmologist to examine the retina and optic nerve in detail — important for detecting early signs of myopia-related complications, especially in moderate to high myopia.

Why Myopia Control in Children Matters

Because the eye continues to grow throughout childhood, myopia diagnosed early in life tends to progress the most — meaning a child diagnosed at age 6 or 7 is likely to reach a higher final degree of myopia by adulthood than one diagnosed at age 11 or 12, if left unmanaged. This is why the modern approach to childhood myopia focuses not only on correcting blurred vision, but on actively slowing the rate at which the eye elongates.

Myopia control using tools such as low-dose atropine, orthokeratology, or specially designed myopia-control spectacle lenses has been shown to meaningfully reduce the rate of progression when started early and used consistently. Because the long-term risk of complications such as retinal detachment and myopic macular degeneration rises with the final degree of myopia reached, slowing progression during childhood can translate into a meaningfully lower lifetime risk of these conditions in adulthood. Regular monitoring, typically every 6 to 12 months during the years of active progression, allows treatment to be adjusted as needed.

Reducing the Risk of Myopia and Slowing Its Progression

While myopia cannot always be prevented — particularly where there is a strong family history — several evidence-based habits can help lower the risk of developing it and help slow its progression once present, especially in children:

Encourage outdoor time: Aim for at least 2 hours of outdoor time a day for children, as natural light exposure is one of the most consistently supported protective factors against myopia onset.
Follow the 20-20-20 rule: During near work, take a 20-second break to look at something 20 feet (about 6 metres) away every 20 minutes, to reduce eye strain from prolonged close focusing.
Maintain good reading and screen habits: Keep reading material and screens at an appropriate distance (generally at least 30cm), and ensure adequate lighting when reading or working up close.
Limit continuous near work and screen time: Encourage regular breaks from books, tablets and phones, particularly for children, rather than long uninterrupted sessions.
Schedule regular eye examinations: Children should have their vision checked regularly from preschool age, as early detection allows myopia control measures to begin when they are most effective.
Don't delay updating prescriptions: Under-corrected myopia does not slow its progression and may in fact worsen eye strain — keep glasses or contact lens prescriptions current.