Diopter reduction with Excimer PRK Laser

Excimer Laser Diopter Reduction surgery is for those who want to get rid of glasses and have been diagnosed with myopia, astigmatism, myopia and myopic astigmatism, hypermetropia.

What disorders can be treated with the Excimer Laser?

Myopia is a refractive error where distance vision is blurred (light rays focus in front of the retina). It can be present from birth or can occur later. Most of the time, myopia progresses (increases) with time. It is differentiated into:

  • Low myopia (diopters up to -3)
  • Medium myopia (between -3 and -6 diopters)
  • High myopia (between -6 and -9 diopters)
  • Strong myopia (more than 10 diopters)

Patients with myopia have a higher risk of retinal detachment. It is advisable to avoid heavy, intense physical effort or blows to the head area. Patients with myopia may wear glasses or contact lenses for better vision and visual comfort. Those who no longer wish to wear glasses may opt for myopia surgery as an alternative.

Hypermetropia is a refractive error where near vision in particular is blurred (light rays focus behind the retina). From birth, there is a physiological hypermetropia that improves as the child grows, as it is part of the normal growth process of the eye. Hypermetropia is divided into:

  • Low hypermetropia (diopters up to +3)
  • Medium hypermetropia (between +3 and +6)
  • High hypermetropia (over 6 diopters)

The presence of hypermetropia is manifested by eye pain, visual fatigue, including headaches. One of the complications of hypermetropia is amblyopia (lazy eye).

Astigmatism is a refractive error where vision is blurred at both distance and near because the cornea is oval-shaped (like a rugby ball) and light rays entering the eye are not clearly focused on the retina.

The presence of astigmatism is manifested by blurred, distorted vision and the need to “squint” to focus the image. It can also be associated with other refractive errors such as “myopia” or “hypermetropia”.

All three refractive errors require glasses for clear vision to avoid eye strain or visual discomfort. They are not corrected by wearing glasses.

Laser surgery is used to correct diopters. The most commonly used laser techniques are:

  • PRK technique – is a technique for correcting diopters using the ZEISS Excimer laser. It consists of the partial removal of the corneal epithelium (the first layer of the cornea) and the application of the laser which shapes the cornea to achieve diopter correction.
  • Femtolasik technique – uses both Excimer and Femto lasers. This technique cuts out a “flap” or cap with great precision and the Excimer laser acts underneath that flap that will be put back in place.
  • Relex Smile technique – is the newest laser technique. This technique does not require epithelial removal (PRK technique) or flap removal (FemtoLasik technique). Femtosecond laser technology is used to correct diopters.

Our clinics use state-of-the-art technology, the ZEISS EXCIMER MEL 90 LASER, used in laser surgeries to correct refractive errors: myopia, hypermetropia and astigmatism.

How do you know you need Excimer Laser surgery?

There are many factors that can determine whether or not you can have Excimer Laser surgery. However, the first questions you will be asked will be these:

  • Are you over 18?
  • Are your eyes healthy?
  • Can you see well with glasses?
  • Do you have a diagnosis of myopia, astigmatism, hypermetropia or myopia and myopic astigmatism?

For many patients between the ages of 20 and 40, laser eye surgery is appropriate.

The following medical conditions may prevent you from undergoing surgery and can only be confirmed during an examination:

  • Eye infections
  • Increased internal eye pressure
  • Dry eyes, epilepsy
  • Diabetes
  • Very large pupils with high correction
  • Rheumatoid polyarthritis, SLE, lupus
  • Keratoconus
  • Macular degeneration
  • Crohn’s or collagen disease
  • Blindness in one eye or partial vision
  • Glaucoma
  • Ocular herpes
  • Corneal dystrophy
  • A strabismus or a prism that is not corrected by the contact lenses
  • If you are pregnant or breastfeeding, we recommend postponing the surgery for 6 months after birth.

What does Excimer Laser surgery involve?

The Excimer laser changes the refractive state of the eye by removing tissue from the cornea. This process uses ultraviolet energy from the Excimer laser to disrupt chemical bonds in the cornea without causing thermal damage to surrounding tissues. The modified anterior corneal surface allows light to be focused on the retina, reducing or eliminating dependence on glasses and contact lenses.

The Excimer laser generates ultraviolet light with a specific wavelength (193 nanometers). By controlling the pulses of the Excimer Laser with a computer, the instrument can create the desired corneal shape.

Excimer laser energy is absorbed by water-containing tissues such as the cornea. The laser energy itself decreases rapidly beyond its focal point. Therefore, the energy of the ultraviolet laser does not penetrate deeper into the eye tissue and therefore does not cause damage to other eye tissues.

In addition to the lack of scarring, another advantage of using the Excimer laser is the incredible accuracy with which tissue can be removed without thermally damaging the surrounding tissue.

What is recommended before Excimer Laser surgery?

  • contact lens wearers must discontinue wearing contact lenses
  • carrying out the necessary investigations for the surgery:
    • determination of visual acuity with best optical correction
    • kerato-refractometry
    • determination of pupil and corneal diameters
    • corneal pachymetry
    • corneal topography
    • corneal examination
    • ocular biometry
    • determination of intraocular pressure
    • cycloplegia with eye drops. Caution! it is recommended that patients do not drive their car under the influence of the eye drops!
    • examination of the fundus

When is Excimer Laser surgery not recommended?

  • Modification of diopters within 12 months
  • Any residual, recurrent or active eye disorder or abnormality of the eye
  • Symptom of Keratoconus
  • Administration of general medication that affects wound closure, such as corticosteroids or anti-metabolic agents
  • Autoimmune diseases (e.g. AIDS)
  • Previous eyeball or corneal surgery of any kind performed on the eye to be treated
  • Diagnosis of autoimmune disease, connective tissue disease or unbalanced diabetes
  • Irregular astigmatism
  • Suspected glaucoma or intraocular pressure > 21 mm Hg
  • History of keratitis with herpes simplex or herpes zoster in the eyes
  • Pregnant or breastfeeding women
  • Patients under 18 years of age

What to expect after Excimer Laser surgery?

The first day after surgery, vision will be blurry for 4-5 hours after surgery and the eyes may feel irritated. Please do not rub your eyes, and follow all instructions and treatments exactly. The day after the surgery, you will have your first check-up with your doctor. During the first few weeks, your vision may fluctuate, and as a side effect you may experience dry eyes. This is very common and can be treated with artificial tears. During the first month it is recommended that you avoid any activity that might involve chemicals, dirt or dust in your eyes. It is also recommended to avoid swimming and contact sports for one month.

If your working environment is dusty, such as on a construction site, you will need to wear a pair of protective glasses at all times. Limitations on practical activities begin to lessen as the cornea continues to heal and dryness improves.

Healing of the corneal epithelium occurs in 3-4 days, during which time the symptoms can be unpleasant, characterized by mild eye pain, burning and foreign object sensations, excessive tearing, photophobia. Post-operative treatment will be received and must be followed at home. Post-operative check-ups are mandatory every 7 days, then depending on the case and the need at 1 month or 3 months, 6 or 12 months.

A therapeutic contact lens is used as a dressing after surgery, so patients will be able to see immediately after the surgery. During the first week the vision is unstable and blurred, with variations in vision between the two eyes. One week after surgery, if the corneal epithelium has healed, the contact lenses are removed.

After lenses removal, treatment with anti-inflammatory eye drops is started as prescribed by the doctor and vision will improve considerably during recovery. Healing to a high extent is within a month, and stabilization of vision takes about several months. Dry eye sensation may occur for several months. The healing process differs from patient to patient. In the long term, the postoperative course is favorable in most cases.

What are the specialist's recommendations after Excimer Laser surgery?

Mandatory to observe

  • The eyes are cleaned with IRIDIUM sterile wet wipes for two weeks.
  • Wash hair as you would at the hairdresser’s, making sure to keep shampoo out of your eyes, for at least two weeks.
  • Before administering the eye drops, wash and disinfect hands.
  • Sunglasses with UV protection are recommended.

Strictly forbidden

  • Sports activities, physical effort (two weeks)
  • Eye contact with water or other not prescribed substances.
  • Areas with heavy dust (one month)
  • Eye rubbing (one month)
  • Make-up or other cosmetics around the eyes (one month)
  • Swimming pool, sauna, jacuzzi, thermal baths (one month)

It is normal

  • Having a stinging sensation, discomfort, swollen eyelids and eye pain (first week)
  • Tearing excessively (first week)
  • Can’t stand natural, artificial light

What are the benefits of Excimer Laser surgery?

  • increased predictability of post-operative outcomes
  • reduced surgery time
  • faster post-operative recovery
  • aspheric profile and ablation quality increase visual comfort at night

The surgery is painless and the anesthesia is local, with eye drops. It does not require hospitalization.

What are the benefits of the Excimer Zeiss MEL 90 laser?

  • The FLEXIQUENCE function gives us the choice between 250 and 500 Hz, which means a reduced surgery time. The 500 Hz frequency can produce an ablation speed of 1.3 seconds for 1 diopter. Shorter treatments are more comfortable for the patient and create less anxiety
  • fast eye tracker with short response time
  • Triple-A profile, the MEL 90 laser’s advanced ablation algorithm combines the available profiles found in previous lasers, and this means fast visual recovery, stable results and low regression rates. LASER retraction surgery is a treatment method that was developed with diopter correction in mind. The surgery is performed on both eyes in the same session. All laser diopter reduction techniques result in corneal reshaping with the aim of changing the refractive power of the cornea, achieving diopter correction.

PRK was the first laser technique to appear, it does not require corneal cutting. The technique is based on the property of the corneal epithelium (the first layer of the cornea) to regenerate naturally and consists of partially removing this layer using an alcohol solution. After removing this layer, the cornea is reshaped using the Excimer laser. Finally, a therapeutic contact lens is applied as a dressing. Reepithelization occurs in 3-4 days, during which time symptoms may be unpleasant, depending on individual tolerance, ranging from blurred vision, tearing, photophobia to stinging, pain. The advantage of this technique is that it does not require cutting the cornea, the disadvantages are the slow recovery, the marked discomfort in the first 24 and 72 hours post-operatively and the higher degree of regression compared to other laser techniques.

The LASEK technique is very similar to the PRK technique. Both involve corneal de-epithelization instead of creating a flap including the stromal layer. The difference between the 2 techniques is the preservation of the epithelium in the case of the LASEK technique. It was originally thought that preserving the epithelium would speed up the healing process. However, practice has proven the opposite, recovery is even slower. With the PRK technique, the eyes are calmer immediately post-operatively and the recovery period is shorter.

Text medically reviewed by Dr. Teodor Holhoș, Ophthalmic Surgeon
Written by Dr. Holhos Team
Surgeries

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Excimer Laser Diopter Reduction surgery is for those who want to get rid of glasses and have been diagnosed with myopia, astigmatism, myopia and myopic astigmatism, hypermetropia.

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