Have you had enough of glasses or contact lenses that restrict your everyday life? The possibility of finally having free and unrestricted vision with laser eye surgery sounds tempting – but are you suitable for it? The path to a life without visual aids begins with the question of whether your eyes meet the requirements for laser eye surgery. In this article, you will find out who is eligible for the various laser procedures, how the minimum age or visual stability play a role and why a healthy cornea is so important. We also highlight specific requirements for Femto-LASIK, PRK and Trans-PRK, look at alternatives such as implantable lensesand explain when laser eye surgery is unfortunately not an option. Read on to find out if you’re ready to take the step towards a clearer life!

Why more and more people are having their eyes lasered

For many people, laser eye treatment is a real turning point: finally a life without glasses or contact lenses. No fogging up of glasses in the rain, no fiddling with contact lenses in the early morning – and all with the freedom of being able to see clearly and sharply at all times. But what makes laser eye surgery so attractive?

Advantages of laser eye surgery:

• See clearly whenever you want: After a successful laser treatment, many people see better than ever before – without aids. A clear view at any distance, whether driving, playing sport or in everyday life.
• Improve quality of life: no glasses that pinch or scratch, no contact lenses that interfere with dry eyes– freedom and comfort instead.
• Save costs: In the long run, you save the constant costs of new glasses, contact lenses, care products or repairs.
• Safety during sport: you no longer have to worry about your glasses or contact lenses, especially during activities such as swimming, running or skiing.
• Modern technology, precise results: Procedures such as Femto-LASIK, ReLEx SMILE or Trans-PRK work precisely and are gentle on the cornea. The treatments are often painless and only take a few minutes.
• Permanent solution: Laser eye surgery can permanently correct many visual defects such as short-sightedness, long-sightedness and astigmatism.

General suitability criteria for laser eye surgery

Minimum age 18 years old – Why age is important

A minimum age of 18 years applies for laser eye surgery, as the development of the eyes is usually not yet complete by then. The visual acuity and refractive power of the eye can change into young adulthood, which plays a decisive role in stable and successful treatment.

Stable visual acuity as a prerequisite for the procedure

Stable visual acuity is one of the most important prerequisites for successful laser eye treatment. This means that the number of dioptres must not have changed significantly in at least one year. This is the only way to ensure that the result of the laser treatment remains permanently stable and that the defective vision does not return.

Why is stable visual acuity crucial?

Laser eye surgery corrects your existing visual impairment – be it short-sightedness, long-sightedness or astigmatism – by precisely shaping the cornea. However, if the visual acuity is not stable, the visual defect may worsen again after the operation as the refractive power of the eye continues to change. In such cases, further treatment may be necessary at a later date.

Who should pay particular attention?

• Young adults: Diopter values can change more frequently in people under the age of 25.
• Hormonal fluctuations: Pregnancy, breastfeeding or hormonal changes can temporarily affect visual acuity.
• Eye diseases: Some diseases such as keratoconus or progressive corneal damagepreclude laser treatment.

How is stability tested?

Before laser eye treatment, ophthalmologists carry out comprehensive preliminary examinations to ensure that your visual acuity is constant. They compare current and previous diopter values and check the thickness and health of the cornea.

Eye health for laser surgery

Good eye health is a basic prerequisite for laser eye surgery. Certain eye diseases canaffect suitability for laser surgery, as they could jeopardize the outcome of the treatment or cause complications. Before the procedure, your eye health will be carefully checked by means of a comprehensive examination.

Glaucoma

Glaucoma is a disease in which the intraocular pressure is increased and the optic nerve is damaged. Laser eye surgery itself does not directly affect eye pressure, but can cause additional stress in already damaged eye sockets. People with controlled glaucoma may be able to undergo laser surgery, but this depends on the individual diagnosis.

Cataracts

In cataracts, the natural lens becomes cloudy, which increasingly impairs vision. As laser eye surgery shapes the cornea and does not affect the lens, this treatment is not suitable for cataracts. In this case, lens surgery, such as replacement with a multifocal lens, is the better choice.

Keratoconus

Keratoconus is a disease in which the cornea becomes irregularly deformed and thinner. As the stability of the cornea is essential for laser eye surgery, keratoconus precludes treatment. In such cases, other procedures, such as crosslinking, can be used to stabilize the cornea.

Inflammation of the eye

Chronic or acute inflammation of the eyessuch as conjunctivitis, corneal infections or inflammation of the eyelid margins must be completely healed before laser treatment can be considered. Inflammation impairs healing and increases the risk of complications.

Other diseases or factors

• Dry eyes: People with severely dry eyes may develop more intense symptoms after laser surgery, which is why tear production is tested in advance.
• Diabetes: Well-controlled diabetes is often not a criterion for exclusion, but diabetic retinal damage can prevent treatment.
• Autoimmune diseases: Diseases such as lupus or rheumatism can impair wound healing and should be clarified in advance.

General physical health

In addition to eye health, general health also plays a decisive role in suitability for laser eye treatment. Certain diseases or physical limitations can impair the healing process after the procedure or increase the risk of complications.

Requirements not met: For whom is laser eye surgery not suitable?

Laser eye surgery offers many people the opportunity to permanently see clearly without glasses or contact lenses. However, not everyone is suitable for laser eye treatment. There are clear contraindications where the procedure is eithernot possible or associated with increased risks. These include certain diseases, physical conditions or individual factors.

Contraindications for laser eye surgery:

1. Insufficient corneal thickness: If the cornea is too thin, the laser cannot work safely without jeopardizing the stability of the cornea.
2. Keratoconus: A condition in which the cornea has a cone-shaped curvature, making laser treatment unsuitable.
3. Pregnancy and breastfeeding: Hormonal fluctuations can affect visual acuity, which is why the procedure should be postponed.
4. Age under 18 years: Visual acuity must be stable, which is often not the case with younger patients.
5. Active eye diseases: Inflammation, infections or diseases such as glaucoma or diabetic retinopathy can be an exclusion criterion.
6. Severe general illnesses: Diseases such as uncontrolled diabetes, lupus or rheumatism impair healing and increase the risk of complications.
7. Severe visual defects outside the laser limits: In the case of extreme diopter values (e.g. over -10 diopters) or severe presbyopia, lasering often cannot achieve the desired correction.
8. Dry eyes: Severely dry eyes can be exacerbated by the procedure and should be clarified before treatment.
9. Mental or neurological illnesses: Conditions such as epilepsy or anxiety disorders can affect performance or recovery after surgery.

Alternatives to laser eye surgery: Implantable lenses or multifocal lenses

If laser eye surgery is not possible due to certain contraindications such as a cornea that is too thin or very high dioptre values, modern lens implants can be an excellent alternative. Two of the most common methods are implantable lenses (ICL) and multifocal lenses.

Implantable lenses (ICL)

With this method, an additional artificial lens is inserted into the eye without removing the natural lens. These implantable contact lenses correct short-sightedness, long-sightedness and astigmatism and provide clear vision at any distance. The advantage:

• No ablation of the cornea, which is why the ICL is also suitable for thin corneas or other laser contraindications.
• Reversibility: The lens can be removed or replaced if necessary.

Multifocal lenses

The multifocal lens replaces the natural lens and is often used for presbyopia or cataracts. These lenses enable sharp vision at several distances (e.g. near and far) and relieve many people of the visual impairment that occurs with increasing age. They are particularly suitable for patients whose refractive errors cannot be corrected with a laser.

Why are these methods often a solution?

• They are independent of corneal thickness and are also suitable for high diopters or presbyopia.
• The procedure is precise and customizable so that individual visual defects can be corrected in a targeted manner.
• They offer long-term results and can be replaced later with more modern lenses if necessary.

Special requirements for laser eye surgery for various procedures

Femto-LASIK

The Femto-LASIK is one of the most modern and most frequently used laser eye surgery procedures. It offers precise and gentle results, especially for patients with stable visual defects such as short-sightedness, long-sightedness or astigmatism. However, the level of diopters and the thickness of the cornea are decisive for suitability, as a safe and permanently stable result can only be achieved within certain limits.

Diopter limits for Femto-LASIK

1. Short-sightedness (myopia)
   • Correction possible up to about -10 diopters, depending on the thickness of the cornea.
   • In the case of extremely high values or a very thin cornea, an alternative method such as the ICLis often preferred.
2. Farsightedness (hyperopia)
   • The limit here is around +4 diopters. As the treatment of long-sightedness removes more tissue, the thickness of the cornea is particularly critical.
3. Astigmatism (curvature of the cornea)
   • Up to 5 diopters can be corrected. Values above this could jeopardize the stability of the cornea.

What influences the limit values?

• Corneal thickness: A minimum thickness of about 500 micrometers is required to ensure that enough cornea remains for stability after laser treatment.
• Corneal health: Diseases such as keratoconus rule out Femto-LASIK.
• Stability of defective vision: The diopter values should not have changed for at least one year.

Trans-PRK

The Trans-PRK (trans-epithelial photorefractive keratectomy) is a variant of laser eye treatment that is particularly suitable for patients with thin corneas or specific requirements. It is a superficial procedure in which no corneal flap is created, making it a safe alternative to Femto-LASIK in certain cases.

Diopter limits for trans-PRK

1. Short-sightedness (myopia)
   • Correction up to about -8 diopters, depending on the thickness and stability of the cornea.
   • For extremely high values, another method such as ICL lenses may be more suitable.
2. Farsightedness (hyperopia)
   • The limit values are around +3 diopters. As more corneal tissue is removed with long-sightedness, the thickness of the cornea is particularly important here.
3. Astigmatism (curvature of the cornea)
   • Up to 4 diopters can be corrected. Higher values require careful individual consideration.

Why is Trans-PRK suitable for thin corneas?

In contrast to Femto-LASIK, Trans-PRK removes the uppermost layer of the cornea (the epithelium) without creating a flap. This makes the method particularly gentle and safe for thin corneas or if the requirements for LASIK are not met. However, healing takes a little longer as the epithelium has to grow back after the procedure.

PRK

The PRK (photorefractive keratectomy) is one of the oldest and most proven laser eye surgery procedures. It is often used for patients with thin corneas or specific limitations when other methods such as Femto-LASIK are not possible. As no corneal flap is created during PRK, more of the cornea is preserved, making it safe for certain patient groups.

Diopter limits for PRK

1. Short-sightedness (myopia)
   • Correction of up to -6 diopters, depending on the thickness and stability of the cornea.
   • Higher values are usually not suitable, as the tissue removal would be too great.
2. Farsightedness (hyperopia)
   • Corrections of up to +3 diopters are possible. Particular care must be taken here to ensure that sufficient corneal tissue is retained.
3. Astigmatism (curvature of the cornea)
   • Up to 4 diopters can be corrected for astigmatism, provided the corneal structure is stable.

Why is PRK a safe alternative?

PRK removes the uppermost layer of the cornea (epithelium) before the laser sculpts the underlying cornea. In contrast to Femto-LASIK or ReLEx SMILE, no flap is created, making it particularly suitable for:

• Patient:inside with a thin cornea.
• People with an increased risk of corneal injuries (e.g. contact sports or high-risk sports).