Who doesn’t dream of waking up in the morning and being able to see clearly straight away – without glasses or contact lenses? But not everyone can have their eyes lasered, as the diopter values play a decisive role. But what are the actual limits? In this article, you will find out up to which values short-sightedness, long-sightedness and astigmatism can be corrected, when alternatives such as lens implantation make sense – and why a preliminary examination is essential to find the best method for your eyes.

Laser eye surgery and diopters: Which visual defects can be corrected?

During laser eye surgery, the refractive power of the eye is changed so that light rays are optimally focused on the retina again. As a result, various visual defects can be permanently corrected. Laser eye treatment is particularly effective for:

• Short-sightedness (myopia) – The eye is too long, light is focused in front of the retina.
• Farsightedness (hyperopia) – The eye is too short, light hits behind the retina.
• Astigmatism – The cornea is unevenly curved, which distorts the image.

How many diopters can be corrected depends on the treatment method, the thickness of the cornea and the individual conditions. In most cases, lasering makes it possible to live without glasses or contact lenses – but there are limits.

Why is there a limit for diopter values?

Not every visual defect can be corrected indefinitely with laser eye treatment. The most important limitation is the thickness of the cornea – it determines how much tissue can be removed to change the refractive power of the eye.

Lasers are used to reshape part of the cornea so that light rays are optimally focused on the retina again. But:

• If the diopter is too high, too much corneal tissue would have to be removed.
• A cornea that is too thin can make the eye unstable and lead to complications.
• Depending on the treatment method, there are different limits for the correction.

The type of defective vision also plays a role. Short-sightedness can usually be corrected more than long-sightedness, as less tissue needs to be removed.

Short-sightedness (myopia) – How many diopters can be stored?

With short-sightedness (myopia ), the eye is too long so that light rays are focused in front of the retina. The result: close objects are seen sharply, distant objects appear blurred.

With laser eye surgery, myopia can usually be corrected up to the following diopter values:

• Femto-LASIK: up to approx. -10 diopters
• Trans-PRK/PRK: up to approx. -6 diopters

Farsightedness (hyperopia) – limits of laser eye surgery

With farsightedness (hyperopia ), the eye is too short so that light rays are focused behind the retina. As a result, close objects appear blurred, while distant objects are often seen sharply.

With laser eye surgery, the correction options for long-sightedness are somewhat more limited than for short-sightedness, as more corneal tissue has to be reshaped:

• Femto-LASIK: up to approx. +4 diopters
• Trans-PRK/PRK: up to approx. +3 diopters

Astigmatism – difficulties with laser eye surgery

With astigmatism, the cornea is not evenly curved, which means that light is not focused precisely on the retina. As a result, both close and distant objects appear blurred.

With laser eye surgery, astigmatism can be corrected up to 6 diopters, whereby the exact limit depends on the method:

• Femto-LASIK: up to approx. 5 diopters (max. 6 diopters)
• Trans-PRK/PRK: up to approx. 3-4 diopters

Why is correction more difficult than for short-sightedness or long-sightedness?

• The cornea must be modeled evenly to achieve a symmetrical curvature.
• The greater the astigmatism, the more complex the laser treatment.
• If the cornea is too thin or the distortion is too strong, lasering can reach its limits.

Femto-LASIK, PRK and Trans-PRK limits at a glance:

Method	Short-sightedness (myopia)	Farsightedness (hyperopia)	Astigmatism (curvature of the cornea)
Femto-LASIK	up to approx. -10 diopters	up to approx. +4 diopters	up to approx. 5-6 diopters
PRK	up to approx. -6 diopters	up to approx. +3 diopters	up to approx. 3-4 diopters
Trans-PRK	up to approx. -6 diopters	up to approx. +3 diopters	up to approx. 3-4 diopters

General requirements for laser eye surgery: Who can have my eyes lasered?

Not everyone with defective vision is automatically suitable for laser eye treatment just because they meet the diopter limits. Whether laser treatment is possible depends on several medical conditions, which are checked in a preliminary examination.

At least 18 years old & stable visual acuity over a longer period of time

For laser eye treatment to be successful, the visual acuity must be stable. Therefore, a minimum age of 18 years applies, as the refractive power of the eye can still change by then. In many cases, ophthalmologists recommend waiting until the diopter values have remained stable for at least a year before surgery.

In principle, there is no maximum age, but laser treatment is often no longer the best choice from around the age of 45. The reason: many people develop presbyopia at this age, which cannot be optimally corrected with conventional refractive laser eye treatment. In such cases, alternatives such as lens replacement (RLA) are often more suitable. People who have presbyopia should choose a special method for presbyopia such as PresbyMAX.

Further requirements for laser eye treatment

• Sufficient corneal thickness – A cornea that is too thin can make laser treatment impossible.
• No serious eye diseases – diseases such as glaucoma, keratoconus or retinal diseases may be a contraindication.
• No untreated eye inflammation or infections – inflammation or dry eyes must be treated before surgery.
• No pregnancy or breastfeeding – hormonal changes can affect visual acuity.
• Healthy general diseases – Uncontrolled diabetes or autoimmune diseases can impair the healing process.

Alternatives: What is possible if the requirements are not met (lens exchange and lens implantation)

Not everyone can have their eyes lasered – whether due to high dioptre values, a cornea that is too thin or other medical restrictions. However, this does not mean that you have to give up a life without glasses or contact lenses. In many cases, there are two proven alternatives:

1. lens implantation (ICL – implantable contact lens)

• An additional artificial lens is inserted into the eye in front of the natural lens.
• Suitable for high myopia above -10 diopters or for thin corneas.
• Preservation of the natural lens, therefore reversible at any time.
• Especially recommended for younger patients under the age of 45.

2. lens exchange (RLA – refractive lens exchange)

• The natural lens is removed and replaced with an artificial intraocular lens (IOL).
• Suitable for severe long-sightedness or in combination with presbyopia.
• A long-term solution, especially for people over 45.
• No later development of cataracts, as the natural lens is replaced.

Arrange a preliminary examination: Do you meet the requirements for laser eye treatment?

The best method can only be determined by a comprehensive preliminary examination.

Have your eyes checked now free of charge! Make an appointment for a personal consultation to find out whether you are suitable for laser eye treatment (free aptitude test) and which method (holistic preliminary examination for 150 euros – creditable towards the operation) is right for you. Your path to a life without glasses or contact lenses starts here!