Laser eye surgery is considered to be one of the safest procedures to permanently see clearly without glasses or contact lenses. However, as with any medical procedure, many people ask themselves: “What are the risks and side effects, and how common are they?” The good news is that thanks to modern technologies and experienced surgeons, serious complications are rare. Nevertheless, before making the decision, you should inform yourself comprehensively about what could occur during and after the treatment – and how you can actively minimize these risks. Stay tuned and read on to find out more about the risks and side effects of laser eye surgery – so that you can start your journey to clearer vision with a good feeling!

Is laser eye surgery dangerous?

Today, laser eye surgery is considered one of the safest methods for permanently correcting vision defects such as short-sightedness, long-sightedness or astigmatism. Thanks to state-of-the-art technologies and precise procedures such as LASIK, Trans-PRK or Femto-LASIK, the complication rate is less than 1% (excluding “normal” side effects). Nevertheless, laser eye surgery, like any operation, is not completely risk-free.

Safe, but with risks

During laser eye treatment, the corneal surface is precisely sculpted to improve visual acuity. As a rule, the procedure is free of complications and most patients are completely symptom-free again after just a few days to weeks. However, there are rare cases in which complications and side effectscan occur, such as infections, dry eyes or slight fluctuations in visual acuity. Serious complications that permanently impair vision are extremely rare and only occur in 0.1% of cases.

Why is education important?

Before you decide to have laser eye surgery, an experienced eye surgeon will provide you with comprehensive information about possible risks and side effects. The purpose of the preliminary examination is to ensure that your eyes are suitable for the procedure. Factors such as the thickness of the cornea, the eye structure and your general state of health are carefully examined to further minimize the risk.

Relatively common side effects of laser eye surgery

Dry eye after the procedure

Dry eyes are one of the most common side effects after laser eye surgery and affect many patients in the first days to weeks after the procedure. This temporary phenomenon is part of the natural healing process, as the corneal nerves are slightly affected during treatment and tear production may be temporarily reduced.

Why does dry eye occur?

During laser treatment, particularly LASIK, a flap is created in the cornea. This procedure disrupts the fine nerves in the corneal surface that are responsible for regulating the tear film. As a result, less tear fluid is produced, which leads to a feeling of dryness.

Symptoms

• Burning and itching in the eye
• Foreign body sensation, as if a grain of sand were in the eye
• Redness and slight irritation
• Reduced visual acuity, especially in the evening or in dry air

Treatment and relief

• Regular use of artificial tears: Your ophthalmologist will prescribe moisturizing eye drops to soothe the eye and stabilize the tear film.
• Avoidance of irritants: Air conditioning, smoke or screen work can exacerbate symptoms and should be reduced.
• Strict aftercare: Touching the eyes with unwashed hands or rubbing the eyes should be avoided at all costs so as not to impair healing.

When does the tear film normalize?

In most cases, the symptoms of dry eyes disappear within a few weeks. For some patients, however, it can take several months for the moisture in the eyes to fully regulate.

Postoperative halos and light sensitivity

After laser eye surgery, some patients report temporary halos and increased sensitivity to light. These symptoms are a common side effect in the first days to weeks after the procedure and are part of the normal healing process.

Why do halos and light sensitivity occur?

During the laser treatment, the cornea is precisely sculpted to correct the visual defect. This procedure changes the way in which light hits the corneal surface and is scattered into the eye.

• Halos are caused by slight irregularities on the cornea, which refract the light and create ring-shaped effects around light sources.
• Light sensitivity can be increased by the healing of the cornea and temporary changes in the tear film.

Symptoms

• Halos: Circles of light around headlights, streetlights or other light sources, especially in the dark.
• Glare: Bright light is perceived as unpleasant or disturbing.
• Increased sensitivity to light: Daylight or screen work can be temporarily exhausting.

How long do the symptoms last?

• Halos and sensitivity to glare are usually most pronounced in the first days to weeks after the operation.
• In most cases, they disappear by themselves as soon as the cornea has fully regenerated and the tear film has stabilized.

Treatment and relief

• Artificial tears: Help to improve eye moisture and relieve symptoms.
• Sunglasses: High-quality sunglasses with UV protection reduce exposure to bright light.
• Avoid sources of glare: Driving at night or prolonged screen time should be reduced until symptoms improve.

When to consult a doctor?

If halos or light sensitivity persist for more than a few months or worsen, you should consult an ophthalmologist. In rare cases, a follow-up correction may be necessary to correct any remaining irregularities on the cornea.

Infections after laser eye surgery

Why can infections occur?

During the procedure, the corneal surface is treated, making the eye temporarily more susceptible to the penetration of bacteria or other germs. Especially with improper aftercare, such as touching the eyes with unwashed hands, germs can enter the treated cornea and triggeran inflammation.

Symptoms of a postoperative infection

• Redness of the eye that lasts longer or gets worse
• Pain in the treated eye
• Reduced visual acuity or suddenly blurred vision
• Strong foreign body sensation or increased lacrimation
• In severe cases: Pus formation or swelling

Treatment of an infection

• Antibiotic eye drops: are prescribed by the ophthalmologist to effectively combat the germs.
• Anti-inflammatory medication: Supplemental as needed to relieve symptoms and support healing.
• Strict monitoring: Regular check-ups ensure that the infection is detected and treated at an early stage.

How you can prevent infections

• Adhere to strict aftercare: Avoid touching the eyes with unwashed hands.
• Use eye drops correctly: Eye drops prescribed by a doctor must be used regularly and as recommended.
• No irritants: Avoid contact with dust, smoke or water from swimming pools for the first few weeks after the operation.
• Wear protective goggles: Particularly important in dusty environments or during outdoor activities.

Over- or undercorrection of visual acuity

Overcorrection or undercorrection is a possible side effect after laser eye surgery that can occur if the desired visual acuity adjustment is not fully achieved. This usually only affects a small percentage of patients, as modern technologies such as Femto-LASIK or Trans-PRK enable a high degree of precision.

Why do over- or undercorrections occur?

• Individual healing processes: Every cornea reacts differently to laser treatment, which can lead to slight deviations.
• Extreme visual defects: With very high diopter values, there is an increased risk of incomplete correction.
• Changes in the corneal structure: If the shape of the cornea does not remain stable as expected, the desired visual acuity may not be fully achieved temporarily or permanently.

Symptoms

• Overcorrection:
  • Slight overcorrection can impair near vision, which is particularly noticeable with short-sightedness.
  • Symptoms include glare, halos or difficulty focusing.
• Undercorrection:
  • Residual errors in the defective vision lead to blurred vision, similar to before the operation.
  • Those affected may still need glasses or contact lenses, albeit with lower diopter values.

Treatment

• Post-correction:
  • In most cases, laser treatment can be repeated (so-called re-laser treatment) to optimize visual acuity. However, this is only possible once the cornea has healed completely and is stable, usually after several months.
• Visual aids:
  • In the case of mild residual defects, glasses or contact lenses can be worn temporarily until a correction is made.

Inflammation of the cornea (keratitis)

Why does keratitis occur?

• Irritation of the cornea: During the procedure, the corneal surface is treated, making it temporarily more sensitive.
• Infection caused by germs: The entry of bacteria or other microorganisms, often due to improper aftercare, can inflame the cornea.
• Delayed healing: In rare cases, the healing process may be impaired, e.g. due to pre-existing conditions such as dry eyes or a weakened corneal structure.

Symptoms of keratitis

• Redness of the eye
• Pain or a strong foreign body sensation
• Reduced visual acuity, partially blurred vision
• Increased lacrimation or sensitivity to light
• In severe cases: Pus formation or swelling

Treatment of keratitis

• Antibiotic eye drops: The doctor prescribes appropriate medication to combat bacterial infections.
• Anti-inflammatory agents: Cortisone drops can reduce inflammation, but should only be used under medical supervision.
• Regular check-ups: Close monitoring by the ophthalmologist is necessary to ensure the healing process and to detect complications at an early stage.

Rare complications with lasering

Corneal decompensation

Corneal decompensation is a rare but serious complication that can occur after laser eye surgery. It describes the condition in which the cornea loses its ability to drain fluid from its tissue and remain clear. This leads to clouding and can significantly impair visual acuity.

Why does corneal decompensation occur?

The cornea has an inner cell layer, the so-called endothelium, which is responsiblefor the drainage of the cornea. Decompensation can occur if this cell layer is damaged by:

• excessive tissue ablation during laser treatment, for example in the case of a very thin cornea.
• Pre-existing diseases of the cornea, such as an already weakened or diseased endothelial layer, cannot be detected.
• Increased intraocular pressure: This can put additional strain on the endothelial cells and lead to decompensation.

Symptoms of corneal decompensation

• Clouding of the cornea: The cornea appears dull or milky, which impairs vision.
• Reduced visual acuity: Patients often experience a permanently blurred image.
• Eye pain or pressure: In some cases, increased intraocular pressure may occur.

Treatment of corneal decompensation

• Eye drops or medication: Anti-inflammatory or pressure-reducing preparations can alleviate the symptoms, but cannot reverse the damage to the endothelial layer.
• Corneal transplantation: In severe cases, only a transplant can restore the function of the cornea. Here, the damaged tissue is replaced with healthy donor tissue.

Ectasia (bulging of the cornea)

Ectasia is a rare but serious complication after laser eye surgery in which the cornea bulges outwards and loses its stability. This bulging leads to a progressive deterioration in visual acuity and can permanently damage the corneal structure if left untreated.

Why does ectasia occur?

Corneal ectasia occurs when the cornea is weakened by the removal of tissue during laser treatment. Patients with are particularly at risk:

• Thin cornea: When the remaining cornea after surgery is not thick enough to support the eye pressure.
• Pre-existing conditions such as keratoconus: This condition, in which the cornea is naturally unstable, can be aggravated by lasering.
• Incorrect planning or execution: Inadequate preliminary examination or treatment outside the safe diopter limits increases the risk.

Symptoms of ectasia

• Increasing visual deterioration: Often accompanied by irregular astigmatism (curvature of the cornea).
• Light sensitivity and halos: Patients notice increased circles of light or glare.
• Double vision or blurred vision: Visual acuity can no longer be fully corrected, even with glasses or contact lenses.

Treatment of corneal ectasia

• Crosslinking: A therapy in which the cornea is treated with UV light and riboflavin (vitamin B2) to stabilize it.
• Special contact lenses: Hard or scleral contact lenses can improve visual acuity by compensating for the irregular corneal surface.
• Corneal transplantation: In severe cases, it may be necessary to replace the damaged cornea with donor tissue.

Permanent visual impairment

Types of permanent visual impairment

• Halos and glare: Light sources appear permanently with circles of light, which can be particularly annoying when driving at night.
• Double vision or ghosting: A shadow or doubling of objects can make vision unclear.
• Reduced visual acuity: The eye does not achieve the desired correction despite the procedure, and even with glasses or contact lenses, visual acuity remains limited.
• Loss of contrast: Colors and details appear less clear, especially in low light conditions.

Causes of permanent visual impairment

• Corneal damage: Irregularities in the corneal surface, e.g. due to uneven healing or ectasia, can cause light to refract incorrectly and impair visual quality.
• Incorrect correction: Too much or too little change in the corneal structure can cause residual visual defects.
• Nerve injuries: Rarely, small nerves can be permanently damaged during laser surgery, affecting tear production or visual adaptation.
• Individual healing: The healing process can vary from person to person and lead to unexpected results.

Treatment options

• Follow-up correction: In many cases, a second laser treatment can correct any remaining visual defects, provided the corneal thickness is sufficient.
• Special contact lenses: Hard or scleral contact lenses help to even out irregular corneal surfaces.
• Long-term therapy: In severe cases, alternative procedures such as corneal transplants or ICL lenses can help.

How you can minimize risk and side effects:

Even though laser eye surgery is considered extremely safe, you can actively contribute to minimizing risks and side effects. Thorough preparation, the choice of an experienced surgeon and conscientious aftercare are crucial. Here is a practical checklist to help you prepare for the procedure and support the healing process:

Checklist: How to minimize risks and side effects

1. Before the operation
   • Seek advice from an experienced ophthalmologist and carry out all the necessary preliminary examinations.
   • Inform your doctor about existing eye diseasesallergies or medication you are taking.
   • Avoid wearing contact lenses for at least one week before the laser treatment, as they can affect the corneal structure.
   • Follow all the doctor’s instructions, e.g. the use of preparatory eye drops.
2. On the day of the operation
   • Avoid make-up, perfume or creams, as residues could impair sterility.
   • Make sure that you are picked up after the operation, as you will not be able to drive yourself.
3. After the operation
   • Use the eye drops prescribed by your doctor, especially antibiotic and moisturizing preparations, as prescribed.
   • Do not touch the eyes with unwashed hands to prevent bacteria from entering.
   • Avoid eye surgery in the first few weeks after the procedure:
     • Rubbing the eyes
     • Swimming pools, saunas and dusty environments
     • Intense physical activities or sports with a risk of injury
   • Wear protective goggles during outdoor activities or if you spend a lot of time in front of screens.
4. Long-term provision
   • Attend all recommended follow-up examinations to monitor healing.
   • Keep your eyes moist by regularly applying artificial tears, especially if you have dry eyes.
   • Inform your doctor if you experience symptoms such as redness, pain or a sudden deterioration in visual acuity.