Vision problems & prescriptions: Questions and Answers

Short sightedness is a condition in which light from distant objects comes to focus in front of the retina instead of on it, which makes distance vision blurred while close vision stays relatively clear.

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It usually happens because the eyeball is slightly too long for its focusing power, or because the cornea is too curved. Both cause the same thing: distance blur.

It is one of the most common reasons people need glasses at all, and uncorrected refractive error is one of the largest contributors to avoidable vision impairment worldwide.

Sources National Eye Institute, National Institutes of Health (US) , American Academy of Ophthalmology , World Health Organization

This information is for educational purposes and does not replace an examination by a qualified eye-care professional.

Short sightedness is caused by the shape of the eye, meaning its length and the curvature of the cornea, and it develops from a combination of inherited tendency and environmental factors such as time spent on close work.

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The contribution of environment is why the conversation about children now includes outdoor time and near-work habits, which is a change from treating short sightedness as purely genetic.

Sources National Eye Institute, National Institutes of Health (US) , Cochrane

This information is for educational purposes and does not replace an examination by a qualified eye-care professional.

Yes, particularly in childhood and the teenage years, when the eye is still growing. Progression usually slows and then stabilises in early adulthood, though it does not stabilise at the same age for everyone.

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A prescription that is still changing is one of the reasons surgery is usually deferred, because a treatment planned from a moving prescription may not match the eye a year later.

Sources National Eye Institute, National Institutes of Health (US) , American Academy of Ophthalmology

This information is for educational purposes and does not replace an examination by a qualified eye-care professional.

The focusing error can be corrected permanently by laser surgery in suitable eyes, in the sense that the corneal reshaping does not reverse. The eye can still change with age, so the prescription can drift later in life.

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Higher short sightedness also carries a slightly higher background risk of retinal problems regardless of whether surgery is performed, which is an argument for continuing regular eye examinations rather than treating correction as the end of the story.

Sources American Academy of Ophthalmology , StatPearls, NCBI Bookshelf

This information is for educational purposes and does not replace an examination by a qualified eye-care professional.

A small amount of regression is possible, and the cornea does not regrow the tissue that was removed. What is more common is a prescription change related to ageing rather than a return of the original error.

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This information is for educational purposes and does not replace an examination by a qualified eye-care professional.

Yes, short sightedness is the refractive error most commonly treated with LASIK. How much can be corrected for a given eye depends on corneal thickness and shape rather than on the prescription alone.

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Sources StatPearls, NCBI Bookshelf

This information is for educational purposes and does not replace an examination by a qualified eye-care professional.

Yes. SMILE is designed for short sightedness and for short sightedness combined with astigmatism, and suitability is assessed from your measurements.

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• What SMILE Pro corrects

Sources StatPearls, NCBI Bookshelf

This information is for educational purposes and does not replace an examination by a qualified eye-care professional.

The options for high short sightedness are laser procedures where the cornea can safely spare the tissue, and lens-based options such as an implantable lens where it cannot. Which applies to you depends on your measurements.

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An important part of the assessment at high prescriptions is the retina rather than the cornea, because highly short sighted eyes are more prone to retinal problems and those should be examined regardless of what is planned at the front of the eye.

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Sources American Academy of Ophthalmology , ESCRS

This information is for educational purposes and does not replace an examination by a qualified eye-care professional.

Long sightedness is a condition in which light comes to focus behind the retina, which the eye can often compensate for at a distance by focusing harder, at the cost of effort and eventual blur.

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That effort is why long sightedness often presents with tired eyes, headaches after reading and symptoms that seem out of proportion to a modest prescription.

Sources National Eye Institute, National Institutes of Health (US) , American Academy of Ophthalmology

This information is for educational purposes and does not replace an examination by a qualified eye-care professional.

Long sightedness is caused by the eye being shorter than its focusing power requires, or by the cornea being flatter than average. It is often present from birth and frequently runs in families.

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Sources National Eye Institute, National Institutes of Health (US)

This information is for educational purposes and does not replace an examination by a qualified eye-care professional.

Long sightedness can be treated with laser correction, but it is assessed more cautiously than short sightedness because treating it requires removing tissue towards the edge of the cornea and outcomes are more variable at higher prescriptions and in older eyes.

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Sources StatPearls, NCBI Bookshelf , The Royal College of Ophthalmologists (UK)

This information is for educational purposes and does not replace an examination by a qualified eye-care professional.

Laser correction can address long sightedness in suitable eyes, but where the condition is mild and only affects reading vision after forty, a different problem may be the real one, and it may have different solutions.

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Distinguishing between long sightedness and presbyopia matters clinically, because they look similar from the inside and are treated differently. That distinction is made during an examination, not from symptoms alone.

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Sources The Royal College of Ophthalmologists (UK)

This information is for educational purposes and does not replace an examination by a qualified eye-care professional.

Astigmatism is a refractive error caused by the cornea or lens being curved more in one direction than another, so light is focused unevenly and vision is blurred or distorted rather than simply out of focus.

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The usual description is that things look smeared or have ghosting at certain angles rather than being uniformly soft, and that is a recognisable difference for many people once it is explained.

Sources National Eye Institute, National Institutes of Health (US) , American Academy of Ophthalmology

This information is for educational purposes and does not replace an examination by a qualified eye-care professional.

Most astigmatism comes from the natural shape of the cornea, and it is often present from birth. It can also be caused or worsened by injury, surgery or a condition such as keratoconus that changes the cornea over time.

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Sources National Eye Institute, National Institutes of Health (US) , American Academy of Ophthalmology

This information is for educational purposes and does not replace an examination by a qualified eye-care professional.

Astigmatism can be corrected with glasses, contact lenses, laser surgery or, in some cases, lens-based surgery. Which one is appropriate depends on the amount, the regularity of the cornea and whether it is stable.

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Sources National Eye Institute, National Institutes of Health (US) , American Academy of Ophthalmology

This information is for educational purposes and does not replace an examination by a qualified eye-care professional.

Yes, astigmatism is routinely treated with LASIK, often together with short or long sightedness in the same procedure. Very large amounts, or astigmatism from an irregular surface, may need a different approach.

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Sources StatPearls, NCBI Bookshelf

This information is for educational purposes and does not replace an examination by a qualified eye-care professional.

Yes. SMILE treats short sightedness with astigmatism, which is the combination it was designed around.

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Sources StatPearls, NCBI Bookshelf

This information is for educational purposes and does not replace an examination by a qualified eye-care professional.

Small residual or regressed astigmatism is possible after any refractive procedure. It is usually measured at follow-up and may be small enough to leave alone, correctable with glasses, or worth a further treatment.

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This information is for educational purposes and does not replace an examination by a qualified eye-care professional.

Standard LASIK corrects distance vision, and it does not restore the near focus that is lost with presbyopia. Some clinics offer specific strategies aimed at reducing reading dependence, and each involves its own trade-offs.

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The strategies usually accepted include monovision, where the two eyes are deliberately treated differently, and a small planned amount of short sightedness in one eye. Both trade some distance sharpness or binocular comfort for near vision.

Whether either suits you depends on your prescription, your work and how you would feel about the compromise, which is why it is a discussion rather than a setting.

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This information is for educational purposes and does not replace an examination by a qualified eye-care professional.

Presbyopia is the age-related loss of the ability to focus on close objects, caused by the natural lens inside the eye becoming less flexible. It affects almost everyone eventually, including people who have had laser eye surgery.

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It is not a disease and not a complication of anything. It is the lens doing what lenses do with age, and it is why reading glasses become necessary in the forties for most people.

Sources National Eye Institute, National Institutes of Health (US) , American Academy of Ophthalmology

This information is for educational purposes and does not replace an examination by a qualified eye-care professional.

Reading glasses become necessary because the lens inside the eye can no longer change shape enough to focus on near objects. The change is gradual and usually noticed first in low light or when tired.

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Sources National Eye Institute, National Institutes of Health (US)

This information is for educational purposes and does not replace an examination by a qualified eye-care professional.

LASIK does not restore the lens’s ability to change focus, so it cannot undo presbyopia. It can be used in strategies that reduce reading dependence, at the cost of some distance sharpness or binocular balance.

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Those strategies include monovision and a small deliberate under-correction in one eye. Both are compromises, and whether a compromise is acceptable depends on your work, your hobbies and how you drive at night.

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Sources American Academy of Ophthalmology

This information is for educational purposes and does not replace an examination by a qualified eye-care professional.

SMILE corrects the focusing error of the cornea, and presbyopia originates in the lens, so SMILE does not restore near focus on its own. It can form part of a plan designed around reading vision, and that plan is a decision made with your surgeon.

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Sources American Academy of Ophthalmology , StatPearls, NCBI Bookshelf

This information is for educational purposes and does not replace an examination by a qualified eye-care professional.

The options for reading vision include reading glasses, varifocals, multifocal contact lenses, and surgical approaches such as monovision or lens replacement. Each trades something, and none restores youthful focusing power.

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Lens replacement is the only option that addresses presbyopia and a developing cataract at the same time, which is why it comes up more often after the mid-fifties.

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Sources American Academy of Ophthalmology , National Institute for Health and Care Excellence (UK)

This information is for educational purposes and does not replace an examination by a qualified eye-care professional.

Monovision means deliberately correcting one eye for distance and the other for near, so the brain combines them. It reduces dependence on reading glasses at the cost of some depth perception and sharpness.

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Many people adapt to it well and some do not, and the way to find out before committing is usually a trial with contact lenses. That trial is worth asking about, because it is cheap and it answers the question directly.

Sources American Academy of Ophthalmology

This information is for educational purposes and does not replace an examination by a qualified eye-care professional.

Age alone does not rule out laser eye surgery after forty. What changes is that presbyopia is arriving, so the discussion includes near vision and the trade-offs involved rather than distance vision alone.

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• What eligibility assessment covers

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This information is for educational purposes and does not replace an examination by a qualified eye-care professional.

Blurred vision most often comes from an uncorrected or changed refractive error, a dry eye surface, or a problem with the lens, retina or optic nerve. Which one it is cannot be established from the symptom alone.

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Two features are genuinely useful when you describe it to a clinician: whether it came on suddenly or gradually, and whether it is present in one eye or both. Those two answers change the urgency and the likely list considerably.

Sources National Eye Institute, National Institutes of Health (US) , American Academy of Ophthalmology

This information is for educational purposes and does not replace an examination by a qualified eye-care professional.

Vision is commonly worse in low light because the pupil widens, which allows more peripheral light through and makes any refractive error more noticeable. Night blur can also relate to dryness, cataract or an irregular corneal surface.

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Sources American Academy of Ophthalmology

This information is for educational purposes and does not replace an examination by a qualified eye-care professional.

Halos and glare around bright lights at night can come from corneal irregularities, cataract, dryness, an uncorrected astigmatism, or the healing phase after refractive surgery. They are a symptom, not a diagnosis.

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In the context of laser surgery, night vision symptoms are one of the most commonly reported side effects early on, and they frequently reduce over months. Persistent or worsening symptoms should be assessed.

Sources American Academy of Ophthalmology , Peer-reviewed literature (via PubMed Central)

This information is for educational purposes and does not replace an examination by a qualified eye-care professional.

Floaters are small opacities in the gel inside the eye that cast shadows on the retina. Many people have some, and longstanding floaters that are not changing are usually not an emergency.

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A sudden increase in floaters, floaters with flashes, or a shadow or curtain across part of the vision is different and needs urgent assessment rather than a routine appointment. That combination can indicate a retinal problem.

Which symptoms need urgent care

Sources National Eye Institute, National Institutes of Health (US) , American Academy of Ophthalmology

This information is for educational purposes and does not replace an examination by a qualified eye-care professional.