Requirements for laser eye surgery: The most important requirements & diopter limits of the procedures

Do you dream of finally being able to see clearly without glasses or contact lenses? Then you may be asking yourself: when is laser eye surgery possible and what requirements must be met? In this blog, you will learn everything you need to know: from the prerequisites such as stable vision and sufficient corneal thickness to possible exclusion criteria such as certain eye diseases. We will also show you why lens surgery can be a good alternative if laser eye surgery is not an option. Stay tuned and find out which treatment method is best for you!

General requirements for laser eye surgery:

Whether your eyes are suitable for laser eye surgery or not can only be determined in the course of a comprehensive preliminary examination. There is no reliable self-test. However, there are some factors that may be known that can indicate suitability. Before we go into the requirements for the individual treatment methods, let’s first take a look at the general requirements that must be met in order to be able to treat short-sightedness, long-sightedness and astigmatism:

From what age is laser eye surgery possible? (> 18 years)

The general rule for laser eye surgery is that you must be at least 18 years old. At this age, the visual acuity is usually stable, as the eye is still developing in the preceding years. In younger patients, there is otherwise a risk that the visual defect will change again after the procedure.

However, from a certain age, typically from around 45 years of age, presbyopia occurs. During this phase, the lens loses its flexibility, making it difficult to see clearly at close range. The risk of developing cataracts also increases. While classic laser eye surgery (e.g. Femto-LASIK or ReLEx SMILE) may still be possible in these cases, it is often not the most effective solution.

For people in this age range, specialized procedures such as PresbyMAX or lens replacement with artificial lenses (e.g. ICL or refractive lenses) are more suitable. These methods not only treat defective vision, but also correct presbyopia or replace the clouded lens before a cataract develops. The result: sharp vision without glasses or contact lenses – even at an advanced age.

Stable visual acuity for at least 1-2 years

Stable vision over a period of at least 1-2 years is one of the most important prerequisites for laser eye surgery. Why? If the visual defect still fluctuates, there is a risk that the refractive power of the eyewill change again afterthe procedure. As a result, the desired effect of being able to see clearly may not be permanent.

Having your eyes lasered during pregnancy and breastfeeding?

Laser eye surgery is not recommended during pregnancy and breastfeeding. This is due to hormonal changes that can affect visual acuity and the cornea. These changes can affect the results of laser treatment.

• Hormonal fluctuations: Can lead to a temporary deterioration or fluctuation in visual acuity.
• Dry eyes: Dry eyes are more common during pregnancy and breastfeeding, which can make healing after laser treatment more difficult.
• Medication: Eye drops are required after laser treatment, the ingredients of which are not ideal during pregnancy or breastfeeding.

It is therefore recommended that laser surgery is only carried out after the breastfeeding period, when the hormone balance has stabilized again.

Reasons for exclusion: When laser eye surgery is not possible

Unfortunately, laser eye surgery is sometimes not possible in cases of visual impairment. This is often due to the fact that certain requirements for laser eye surgery are not met:

Cornea too thin

A thin cornea can be an exclusion criterion for laser eye surgery. As corneal tissue is removed during procedures such as Femto-LASIK or LASIK, the cornea must be thick enough to ensure the stability of the eye. If the cornea is too thin, the eye could be structurally weakened after the procedure.

Eye diseases: Glaucoma, keratoconus & Co.

• Cataract: Clouds the lens and makes correction of the cornea ineffective.
• Glaucoma: Increased intraocular pressure can be further impaired by laser treatment.
• Keratoconus: A pathological deformation of the cornea that could be worsened by lasering.
• Severe dry eyes: Increases the risk of healing problems and can lead to chronic discomfort.
• Retinal diseases: Impair vision, so corneal surgery does not solve the problem.

General diseases (autoimmune diseases)

• Autoimmune diseases (e.g. rheumatism): Slow down wound healing and increase the risk of inflammation.
• Advanced diabetes: Can lead to retinal damage and increase the risk of complications after treatment.
• Severe immunodeficiencies (e.g. HIV): Weaken the immune system, which increases the risk of infection after the procedure.
• Herpes infections of the eye: Can break out again after treatment and damage the cornea.

LASIK or Femto-LASIK Prerequisites:

The Femto-LASIK is a precise and modern form of LASIK in which a femtosecond laser is used to create a thin flap in the cornea. The underlying cornea is then sculpted with an excimer laser to correct vision defects.

• Diopter limits:
  • Short-sightedness: up to -10 diopters
  • Farsightedness: up to +4 diopters
  • Astigmatism: up to 5 diopters
• Particularly suitable for: Patients with a sufficiently thick cornea and stable visual acuity who wish to correct a medium to high visual defect.
• Not suitable for: Patients with very thin corneas or eye diseases such as keratoconus. Femto-LASIK could also be problematic if the eyes are very dry, as the flap makes healing more difficult.

Trans-PRK laser eye treatment:

The Trans-PRK (Transepithelial Photorefractive Keratectomy) is a superficial method in which the uppermost layer of the cornea is removed before the underlying area is sculpted with a laser. In contrast to LASIK, no flap is cut.

• Diopter limits:
  • Short-sightedness: up to -6 diopters
  • Farsightedness: up to +3 diopters
  • Astigmatism: up to 4 diopters
• Particularly suitable for: Patients with thin corneas or people who play sports where a corneal flap could pose a risk.
• Not suitable for: Severe visual defects or if rapid healing is desired, as the recovery time after Trans-PRK is longer than with Femto-LASIK.

SmartSight and ReLEx SMILE requirements for laser eye surgery:

With the SmartSight and ReLEx SMILE-method, a small incision is made in the cornea and a thin slice of tissue (lenticule) is removed without creating a large flap. This minimally invasive technique reduces the risk of dry eyes and largely preserves the corneal structure.

• Diopter limits:
  • Short-sightedness: up to -10 diopters
  • Astigmatism: up to 5 diopters
  • Farsightedness cannot yet be corrected
• Particularly suitable for: Patients with myopia and astigmatism who prefer a minimally invasive procedure with rapid healing.
• Not suitable for: Farsightedness, as this method is currently only used for myopia and astigmatism. ReLEx SMILE may also not be ideal for very thin corneas.

Lens operations as an alternative if the requirements are not met

Even if the lack of vision cannot be treated with laser eye surgery, this does not automatically mean that you have to continue to rely on visual aids. Lens surgery can be an excellent alternative to laser eye surgery in most cases.

• Higher diopter values: Lens surgery enables the correction of extreme visual defects, such as short-sightedness upto -18 diopters or long-sightedness up to +10 diopters, which are often no longer treatable with laser treatments such as LASIK.
• Thin cornea: If the cornea is too thin, making laser eye surgery unsafe, the cornea remains untouched during lens implantation. This is particularly beneficial for patients with structural problems of the cornea.
• No change to the cornea: While the cornea is sculpted during laser eye surgery, it remains intact during lens surgery. This means that the eye is not weakened and the risk of complications such as corneal thinning is avoided.
• Long-term solution: Refractive lens exchange replaces the natural lens with an artificial lens which, unlike the natural lens, does not age. This means that the correction is permanent and presbyopia or incipient cat aracts are also treated at the same time.
• Reversibility: An implanted lens (ICL) can be removed or replaced if necessary, which makes this method flexible.

Lens implantation

The ICL (implantable contact lens) is an alternative for patients for whom laser eye surgery is not an option. An artificial lens is inserted into the eye without altering the cornea, which is particularly advantageous in cases of high ametropia or thin corneas.

• Diopter limits:
  • Short-sightedness: up to -18 diopters
  • Farsightedness: up to +10 diopters
  • Astigmatism: up to 6 diopters

Lens exchange / cataract surgery

In refractive lens exchange / cataract surgery, the eye’s natural lens is replaced with an artificial lens. This method is often used for older patients who suffer from presbyopia or incipient cataracts in addition to defective vision. Eye diseases such as cataracts can be completely cured and even prevented by this treatment method.

• Diopter limits:
  • Nearsightedness/farsightedness: Correctable in almost all diopter ranges.
  • Special toric lenses are suitable for astigmatism

Arrange a free, non-binding aptitude test now:

Are you over 18 years old, do you meet the general requirements and would you like your visual defect to disappear in the best case scenario? Anyone who would like to have their eyes lasered is cordially invited by us at EyeLaser Vienna to a free and non-binding aptitude test or a non-binding preliminary examination.

Together we will quickly find out whether the personal requirements for laser correction are met and then determine the most suitable treatment method!

Make an appointment now