What are the main types of laser eye surgery?

There are several types of laser eye surgery, and each works in a slightly different way. The right treatment will depend on your prescription, cornea, age, eye health and whether you are a suitable candidate.

Lasik

LASIK, also known as laser assisted in situ keratomileusis, is one of the most common forms of laser vision correction. During LASIK, a flap is created in the cornea before the laser reshapes the corneal tissue underneath. LASIK may not be suitable for patients with thin corneas, severe dry eyes, an unstable prescription or certain eye diseases.

Lasek and PRK

LASEK and PRK are surface-based forms of refractive surgery. They do not involve the same corneal flap as LASIK, but they still reshape the cornea to improve focus. These procedures may be considered where LASIK is unsuitable, but they are still not suitable for laser eye treatment in every case.

Smile

SMILE is another form of laser vision correction. It uses a small incision to remove tissue from within the cornea. It may be suitable for some patients with short sightedness, but suitability still depends on prescription, corneal thickness and general eye health.

Lens-based alternatives

Some patients who are not suitable for laser eye surgery may be advised to consider alternatives such as lens replacement surgery, refractive lens exchange, implantable lenses, corrective lenses or continuing with glasses and contact lenses. Refractive lens exchange may be more appropriate for some older patients, particularly where natural lens changes are affecting vision. Cataract surgery may also be needed if cataracts are present.

Who should not have laser eye surgery?

Laser eye surgery can be an effective form of vision correction, but it is not suitable for everyone. A responsible surgeon or practitioner should assess your eyes, medical history and expectations before recommending treatment. If this assessment is rushed, incomplete or inaccurate, you may be exposed to avoidable harm.

Below are some of the groups who may not be suitable candidates for laser eye surgery.

People with an unstable prescription

A stable prescription is one of the most important requirements for laser eye surgery. If your glasses or contact lens prescription has changed significantly in the past year, you may not be suitable for treatment yet.

This is because laser eye surgery corrects your current prescription. If your eyes continue to change after treatment, the result may not last and you may still need glasses, contact lenses or further correction later on.

Most professional guidance expects a stable refraction, usually with no more than a 0.50 dioptre change over 12 months, before laser eye surgery is considered. Patients in their early twenties may also be advised to wait if their prescription is still changing.

People under 18 or whose eyes are still developing

Patients under 18 are generally not considered suitable for laser eye surgery because their eyes are still developing. Many surgeons prefer patients to be at least 21 before considering laser vision correction, as the eyes are more likely to have fully developed by this point.

Younger patients may not be good candidates if their prescription has not settled. Proceeding too early can lead to unpredictable results and a continued need for glasses or contact lenses.

A proper suitability assessment should take age, eye development and prescription stability into account before any treatment is recommended.

People with thin or irregular corneas

Laser eye surgery works by reshaping the cornea, so corneal thickness is a key part of the suitability assessment. The cornea must have enough thickness to maintain its structure after treatment.

If the cornea is too thin or irregular, removing corneal tissue may weaken the eye and increase the risk of complications. One serious risk is corneal ectasia, where the cornea becomes progressively thinner and begins to bulge outwards.

Modern screening should identify subtle corneal thickness problems before surgery. Patients with keratoconus are generally not suitable for laser eye surgery because the condition already causes progressive thinning of the cornea. In more serious cases, corneal damage may require further treatment, and a corneal transplant may be discussed.

People with severe dry eyes

Patients with severe dry eyes may not be suitable for laser eye surgery. Dry eye symptoms can become worse after treatment and may cause:

• Burning
• Grittiness
• Watering
• Blurred vision
• Light sensitivity
• Long-term discomfort

A proper consultation should include checks for dry eyes before any eye surgery is recommended. If dry eyes are identified, treatment may be needed before a patient can be considered suitable for laser vision correction.

Ignoring dry eyes before surgery may increase the risk of poor healing, discomfort and dissatisfaction with the outcome.

People with certain eye conditions

Certain eye conditions may mean you are not suitable for laser eye surgery, or that treatment should be delayed. These can include:

• Glaucoma
• Cataracts
• Keratoconus
• Active eye infections
• Previous eye injuries
• Retinal detachment
• High eye pressure

Patients with large pupils and a high prescription may also face a higher risk of glare, halos and night vision problems after surgery. A history of herpes eye infection, including herpes zoster, should also be assessed carefully before treatment is recommended.

If a practitioner fails to identify these risks during the consultation stage, this may raise concerns about whether the correct standard of care was followed.

People with certain medical conditions

Some medical conditions can affect whether a patient is suitable for laser eye surgery. Poorly controlled diabetes can affect eye health and healing after laser eye surgery, while autoimmune diseases such as rheumatoid arthritis may increase the risk of poor recovery.

Conditions such as lupus, Marfan syndrome or a compromised immune system do not always make laser eye surgery impossible, but they must be assessed carefully before treatment is approved.

A practitioner should also review any prescription medication you take, as some medicines can affect healing, dry eyes or infection risk. This forms part of the duty of care owed to patients before any procedure.

People who are pregnant or breastfeeding

Pregnancy and breastfeeding can temporarily affect vision, dry eyes and prescription stability. Hormonal changes can alter the shape of the eye, which may make laser eye surgery results less predictable.

For this reason, laser eye surgery is usually delayed until the eyes have settled. This does not necessarily mean a patient will never be suitable for laser eye treatment, but surgery should not be rushed during a period where vision may still be changing.

People with unrealistic expectations

Patients who expect perfect vision may not be good candidates for laser eye surgery. The aim of vision correction is usually to reduce reliance on glasses or contact lenses, not to guarantee flawless eyesight in every situation.

Some patients may still need glasses, contact lenses or corrective lenses for certain tasks after surgery. Others may experience side effects such as glare, halos or dry eyes.

A surgeon or practitioner should explain the realistic outcomes, potential risks and alternative treatment options before surgery. If this does not happen, the patient may not be able to make a properly informed decision.

What should a practitioner assess before laser eye surgery?

Before recommending laser eye surgery, a practitioner should carry out a detailed suitability assessment. This is important because not every patient is a safe candidate for refractive surgery.

A practitioner should assess:

• Prescription stability: whether your glasses or contact lens prescription has changed recently.
• Corneal thickness: whether there is enough corneal tissue for safe treatment.
• Corneal shape: whether the cornea is regular or whether there are signs of conditions such as keratoconus.
• Dry eyes: whether you already have dry eye symptoms that could worsen after treatment.
• Pupil size: whether large pupils may increase the risk of glare, halos or night vision problems.
• Eye pressure: whether there are signs of high eye pressure or glaucoma risk.
• Existing eye conditions: including cataracts, retinal problems, active infections or previous eye injuries.
• Medical history: including conditions such as diabetes, autoimmune disease or immune system problems.
• Prescription drugs: whether any medication could affect healing, dry eyes or infection risk.
• Previous eye surgery: whether earlier procedures could make laser eye surgery unsafe or less predictable.
• Pregnancy or breastfeeding: whether temporary hormonal changes could affect vision or prescription stability.
• Realistic expectations: whether the patient understands the likely outcome, limitations and risks.

They should also consider whether you are a suitable candidate for refractive surgery, or whether another option, such as refractive lens exchange, would be safer. Practitioners have a duty to treat patients with proper care, which includes identifying when someone is not suitable for laser eye surgery.

What should happen during and after laser eye surgery?

During surgery, the surgeon must perform the eye surgery to the expected standard. This includes:

• Using the correct surgical method: the technique should be suitable for the patient’s eyes and agreed treatment plan.
• Applying appropriate laser settings: the settings should be based on accurate measurements and the patient’s prescription.
• Maintaining proper hygiene: the clinic should follow infection control procedures to reduce avoidable risks.
• Following safety processes: checks should be completed before and during treatment to help prevent errors.
• Acting with care and precision: the procedure should be performed in line with accepted professional standards.
• Monitoring for complications: after surgery, the clinic should monitor your healing and check for any signs that something has gone wrong.

Practitioners have a duty of care to perform laser eye surgery to the expected standard and provide appropriate follow-up care. This includes taking reasonable steps to reduce the risk of preventable complications, giving clear aftercare advice, monitoring recovery and acting promptly if signs of a problem develop.

What can happen if an unsuitable patient has laser eye surgery?

If someone who is not suitable for laser eye surgery goes ahead with treatment, the outcome can be serious. Laser eye surgery changes the shape of the cornea, so careful checks are needed before treatment to confirm whether the eyes are healthy enough, the prescription is stable and the patient understands the likely results.

If these checks are not carried out properly, or warning signs are ignored, an unsuitable patient may experience:

• Poor vision correction: the surgery may not achieve the intended result, meaning the patient still needs glasses or contact lenses.
• Worsened vision: in some cases, vision may become less clear than it was before surgery.
• Persistent dry eyes: laser eye surgery can make dry eye symptoms worse, leading to burning, grittiness, watering and discomfort.
• Blurred or fluctuating vision: vision may change throughout the day, especially when reading, working on screens or driving.
• Night vision problems: some patients experience glare, halos or starbursts around lights, which can make night driving difficult.
• Double vision: this can affect focus, balance and the ability to carry out normal daily tasks.
• Eye infections: infection is a possible complication of any eye procedure and may require urgent medical treatment.
• Corneal damage: patients with thin or irregular corneas may be at higher risk of corneal weakening, bulging or long-term structural problems.
• Light sensitivity: bright lights may become uncomfortable or painful, particularly in the early recovery period or if complications develop.
• Need for further treatment: some patients may require medication, specialist eye care, further laser correction or more invasive eye surgery.

These problems can affect more than eyesight. They may interfere with work, driving, screen use, reading, confidence and general day-to-day life. For some patients, the emotional impact can also be significant, especially if they were not properly warned about the risks or realistic outcome before treatment.

If laser eye surgery was carried out on someone who should not have been considered suitable, this may raise concerns about whether the practitioner met their duty of care. This includes assessing suitability, explaining risks of laser eye surgery clearly and providing appropriate aftercare if complications develop.

When could unsuitable laser eye surgery be negligence?

A poor result does not automatically mean negligence. All surgery carries some level of risk, and some complications can occur even when the correct standard of care has been followed. However, a claim may be possible if your practitioner failed to assess whether you were suitable for laser eye surgery, ignored clear risk factors, failed to explain potential risks or allowed surgery to go ahead without informed consent.

Negligence may also occur if:

• The suitability assessment was inadequate: the practitioner should have taken reasonable steps to confirm whether laser eye surgery was appropriate for you before treatment went ahead.
• Known risk factors were overlooked or ignored: if there were signs that you were not a suitable candidate, these should have been carefully considered before surgery was recommended.
• The risks, limitations or alternatives were not properly explained: you should have been given clear information about what the procedure could and could not achieve, as well as other treatment options.
• You were not given enough information to make an informed decision: consent is only valid if you understood the key risks, possible outcomes and alternatives before agreeing to surgery.
• The surgery was performed below the expected standard: errors during treatment may amount to negligence if they caused avoidable harm.
• The clinic failed to provide appropriate follow-up care: aftercare is an important part of the treatment process and should help identify issues during recovery.
• Complications were not monitored or acted on properly: if warning signs were missed, dismissed or not treated promptly, this may make the outcome worse.

If any of these failures caused avoidable harm, you may be able to make a laser eye surgery negligence claim.