Nearsightedness - Farsightedness - Astigmatism

The eye is shaped as a slightly irregular hollow sphere that takes in light and translates it into images.

Light first passes through the cornea, the clear front “window” of the eye. The cornea’s refractive power bends (refracts) the light rays that move freely through the pupil the opening in the center of the iris through which light enters the eye.

The iris (the colored part of the eye) works like a shutter in a camera, it opens and closes. It has the ability to control the diameter and size of the pupil and thus the amount of light entering the eye.

After passing through the iris, the light rays pass thru the eye’s natural crystalline lens. This clear, flexible structure works like the lens in a camera, shortening and lengthening its width in order to focus light rays properly.

Light rays pass through a dense, transparent gel-like substance, called the vitreous that fills the globe of the eyeball and helps the eye hold its spherical shape.

In a normal eye, the light rays come to a sharp focusing point on the retina. The retina functions much like the film in a camera. It is responsible for capturing all of the light rays, processing them into light impulses, then sending them to the optic nerve.

Emmetropia

The condition in which the refractive power of the cornea and the axial length of the eye balance out, causing the light rays to focus perfectly on the back of the retina is called emmetropia. An emmetropic eye requires no corrective lenses.

Ametropia

The condition in which the light rays do not focus properly on the retina is called ametropia. This state indicates that a refractive error is present (nearsightedness-farsightedness-astigmatism) and the individual cannot see clearly.

The shape of the eye is very important in keeping things we see in focus. Problems with the shape of the cornea can keep you from seeing clearly. During laser vision correction, special instruments reshape the cornea. This lets the cornea focus light better so the vision is closer to normal.

Myopia - Nearsightedness
With myopia, the curve of the cornea is too steep. This makes the distance between the cornea and the retina too long. Light rays from distant objects focus in front of the retina, making them look blurry.

Hyperopia - Farsightedness 
With hyperopia, the curve of the cornea is too flat. This makes the distance between the cornea and the retina too short. Light rays from the close objects focus behind the retina, making them look blurry.

Astigmatism 
With astigmatism, the cornea is oval-shaped instead of round, making both distant and near object look distorted.

These vision conditions affect people from all walks of life and of all ages. Family history increases a person’s likeliness of developing nearsightedness-farsightedness and/or astigmatism.

Common symptoms of refractive errors include:

  1. Blurry vision
  2. Double vision
  3. Distortion of images
  4. Frequent squinting
  5. Halos and glare when looking at bright lights
  6. Difficulty driving or navigating
  7. Headaches
  8. Eyestrain

Today’s technological advancements allow us to predict if a child will become nearsighted or farsighted, as well as to measure the amount and axis of astigmatism at an early age (first or second year of life).

Refractive errors can be detected during a comprehensive eye examination that includes the following tests:

  1. Patient history: past and present vision and medical issues, as well as a detailed family history.
  2. Visual acuity: reading charts are often used to measure visual acuity of each eye, individually and together, both with and without corrective lenses at distance and near.
  3. Preliminary tests: evaluations of depth perception, color vision, eye muscle movements, peripheral or side vision, and the way the pupils respond to light.
  4. Computerized corneal topography: imagery that provides a multitude of corneal refractive (keratometric), topometric, tomographic, and pachymetric data.
  5. Biometry: imagery that provides data regarding the power of the cornea and the axial length of the eye.
  6. Refraction: using a phoropter, a series of lenses are placed in front of the eye in order to determine the lens power that the patient needs to compensate for any refractive error (nearsightedness, farsightedness or astigmatism). This testing can also be done with mydriatic drops that paralyze the ciliary muscle of the eye and results in a loss of accommodation. Accommodation paralysis allows us to determine the true refractive error of the eye.
  7. Eye health evaluation: biomicroscopic examination of the anterior and posterior segment of the eye.

Nearsightedness-Farsightedness and/or Astigmatism are the most common eye conditions worldwide and the available treatment options are the following:

  1. Eyeglasses: the simplest and safest way to correct a refractive error, appropriate lenses provide optimal vision.
  2. Contact lenses: may provide clearer vision, a wider field of vision, and greater comfort than spectacles. Individuals who wear contact lenses though have a higher risk for developing an eye infection. More precisely, statistics show that 1 out of 1000 -over a decade- contact lens wearers will develop serious infectious keratitis (corneal infection), while some of these cases will undergo corneal transplant procedure to manage this complication.
  3. Refractive Surgery: provides the ability to work, drive, read the clock, play sports, ride horseback-do just about everything- without always having to reach for glasses or contacts. If an individual is a good candidate for laser vision correction, the eye doctor can reshape the surface of the cornea using a laser. This change in eye shape restores the focusing power of the eye by allowing the light rays to focus precisely on the retina and the result can be a dramatic improvement in someone’s vision-and lifestyle. There are many types of refractive surgeries.

The preoperative eye evaluation is an extremely important and structured examination to determine whether a patient is a good candidate for Laser Vision Correction and to decide which procedure is suitable for each individual. Our team performs one of the most comprehensive ocular exams done today. Our preoperative examination protocol is internationally recognized and taught in relevant courses worldwide.

Potential candidates must meet the following basic criteria:

  • Candidates should be at least 18 years old.
  • Vision and prescription should be stable for at least 1 year prior to any refractive procedure.
  • An individual should not have any other eye conditions/diseases that might affect the outcome of the procedure.
  • Candidates should not be nursing or pregnant when undergoing a refractive procedure.

 

Apart from a thorough manifest and cycloplegic refraction to determine the lens power that the patient needs to compensate for any refractive error (nearsightedness, farsightedness or astigmatism), certain aspects should be taken into consideration as well, including:

  • Corneal pachymetry

Accurate corneal thickness measurements are essential to evaluate the proper surgical technique for every candidate. We can measure corneal thickness using 3 specialized diagnostic devices (OCT pachymetry,

  • Corneal surface

Corneal topography allows us to map the anterior and posterior surface and curvature of the cornea. It is a critical diagnostic tool in detecting corneal abnormalities and provides a multitude of corneal refractive (keratometric), topometric, tomographic, and pachymetric data. This information is acquired by using the Pentacam and Wavelight Oculyzer II technology.

  • Corneal epithelium

OCT epithelial mapping across a 9-mm wide corneal area, is an essential measurement in refractive surgery candidates. Epithelial thickness mapping can help us identify early keratoconus, an eye disorder that results in progressive thinning of the cornea. It also contributes to dryness detection and contact lens-related warpage diagnosis.

  • Accuracy in the axis and amount of corneal astigmatism

Corneal astigmatism is measured with 4 different diagnostic devices (Pentacam, Wavelight Oculyzer II, Cassini, Wavelight Topolyzer Vario).

  • Pupil size

Procyon device provides scotopic-mesopic and photopic evaluation. This measurement determines the quality of vision under low light conditions.

Is the most common refractive procedure to treat myopia-hyperopia and astigmatism worldwide. The principle of LASIK is to change the corneal curvature, thus correct the refractive error and focus incident light on the retina. In this technique, a flap is created on the surface of the cornea with a femtosecond laser. Then the flap is lifted and an excimer laser reshapes the cornea by removing tissue from the exposed stromal bed. The last step of the procedure is the repositioning of the corneal flap, which heals within hours.

We have been performing LASIK procedures with Femtosecond Laser (bladeless flap creation) since 2006 and our institute was the first to apply this technique in Greece, while today in the US femtosecond laser is being used in 60% of the LASIK procedures.

This procedure combines LASIK and corneal cross-linking (riboflavin/ultraviolet A). We introduced this technique in 2008 and has received worldwide acceptance as a clinical tool to "stabilize" high myopic and astigmatic corrections especially in young patients and as a mandatory tool in hyperopic LASIK.

In PRK (photorefractive keratectomy) the corneal epithelium (outer layer of the cornea) is removed, then discarded and the excimer laser reshapes the underlying corneal tissue. By the end of the procedure a bandage contact lens is inserted to protect the cornea as the epithelium grows back over the next 3-4 days. Variations of PRK are known as LASEK & Epi LASIK.

Small incision lenticule extraction (SMILE) is a relatively new refractive procedure designed to treat refractive errors. In this technique a femtosecond laser creates a corneal lenticule which is extracted whole through a small incision without the use of an excimer laser.

In this procedure an implantable lens is inserted between the iris and the natural lens through a tiny incision. It corrects a multitude of refractive errors (myopia-hyperopia and/or astigmatism) and is an option for patients who cannot have LASIK, PRK or SMILE because of high prescription and/or thin corneas. The procedure takes approximately 15 minutes per eye and the patient receives topical anesthetic drops.

LASIK

  • Recovery of vision is rapid, patients have useful vision within a few hours of the procedure.
  • There is little or no discomfort, both during and after the operation.
  • LASIK procedure can correct up to -13/-14 diopters in myopic cases.
  • Typically, post-operative medication drops (antibiotic & steroid anti-inflammatory) are required for one week only.
  • It is the main technique performed in hyperopia and high astigmatism.
  • It improves post refractive stability and lowers enhancement rates.
  • The creation of the flap also cuts corneal nerves and can increase dry eye symptoms in patients who are predisposed to this problem.
  • It cannot be performed on patients with thin corneas or patients whose corneas have an unusual shape.

PRK

  • No corneal incision is required. This leaves a greater portion of the cornea untouched by the procedure, which is important in patients who have thin corneas.
  • It may provide an extra margin of safety in patients with corneal abnormalities, because it leaves a large amount of the cornea untouched.
  • Patients with hyperopia or high astigmatism cannot undergo PRK procedure.
  • It takes several days for visual recovery.
  • It is suitable for myopia lower than -5 diopters.
  • There can be mild to moderate eye discomfort for the first couple of days after the operation.
  • PRK patients are usually required to take cortisone drops for up to 2 months after the procedure, the purpose of these drops is to minimize the risk of the development of haze in the cornea. 

Through the use of cutting edge technology the Wavelight Refractive suite combines speed with customized capabilities to deliver accurate patient specific outcomes. It consists of 2 types of laser: Femtosecond laser FS200 and Excimer EX500.

The WaveLight® EX500 Excimer Laser is the only excimer laser to operate at 500 Hz, with an average treatment time of approximately 1.4 seconds per diopter.

The WaveLight® FS200 Femtosecond Laser is the fastest femtosecond laser available with a standard flap creation time of approximately 6 seconds.

The swivel bed is designed to optimize time between the flap creation and laser procedures.

Suits’ innovative engineering helps reduce the potential for:

  1. Stromal dehydration of the cornea.
  2. Flap shrinkage.
  3. Sensitivity to eye movements.
  4. Patient fixation fatigue.

The advantages of this technology include:

  • Customized treatments for each patient.
  • Eye movement tracking with just 2 milliseconds of latency.
  • Dynamic pupil tracking from 1.5 mm to 8.0 mm.
  • Both laser systems are linked with WaveLight®diagnostic products for seamless and efficient data transfer and treatment planning.
  • Faster treatment times.

Like any other surgical procedure, laser vision correction has potential risks that should be considered. Before electing to undergo the procedure, the medical personnel and the surgeon will outline the benefits and risks and make sure you are aware of all possible outcomes.

The risks of refractive surgery include:

  1. Infection, inflammation (approximately 1/5000)
  2. Loss of vision
  3. Progressive corneal thinning, ectasia (especially associated with eye – rubbing)
  4. Dry eyes or an increase in pre-existing dry eye problem, for the first months of the procedure, most common in women
  5. Possibility of retreatment
  6. Greater sensitivity to glare or seeing halos around lights (most often temporary)
  7. Tiny wrinkles in the corneal flap, requiring a repositioning of the flap

 

Our team is internationally renowned in the expert management of most of these rare compilations, and of course takes extra care in minimizing the potential risk.

Discomfort during the first few days following refractive procedures, such as foreign body sensation – blurred vision – itchiness – lacrimation – redness – eye lid swelling – light sensitivity and headache, is normal and to be expected. These symptoms are temporary and will disappear completely within a few days.

The use of corticosteroid eye drops, may temporarily increase the intraocular pressure. We will closely monitor the eye pressure and add medication eye drops if needed.

Our team has extensive clinical experience of over ten thousand successful refractive procedures. We have published techniques that provide better and safer outcomes and have taught them in courses worldwide.

As mentioned above, on your consultation day, you will be provided with all the necessary information regarding the risks, benefits and possible outcomes of a refractive procedure. You will have the opportunity to ask and clarify any questions during this process in order to make an informed decision. Before proceeding with any operation, you will be asked to sign the informed consent form.

Do's

  • Have someone drive you home after LASIK / PRK / SMILE. You won't see clearly enough to drive.
  • Use your eye drops exactly as directed and keep all follow-up visits with your eye doctor.
  • Wear sunglasses when you're outdoors-your eye may be sensitive to bright light until it heals.
  • Protect your eye from getting bumped as it heals.

 

Don'ts

  • Don't rub or bump your eye. Touching or rubbing your eye may prevent the healing layer of cornea from reattaching properly.
  • Don't plan to return to work until your doctor says it's OK, usually in a day or two.
  • Don't drive until your vision clears (usually the first day after LASIK or SMILE, one week after PRK). 
  • Don't go swimming, sit in a whirlpool or hot tub, play active sports, or wear eye makeup until advised your doctor. (Usually one week)
  • PRK requires sun protection for about two months (good sunglasses cap/hat).

 

Your Follow-up Visits

After the procedure, our team regularly checks that your cornea is healing properly. Depending on how your eye heals, a second LASIK treatment (called enhancement) may be needed to bring your vision even closer to normal. In some cases, glasses or contacts may still be needed, but with a much weaker prescription. The expert surgeon may wait to see the results of your first LASIK before treating your other eye.

Eye drops schedule

  • Vigamox: one drop in the operative eye, four times a day for a week.
  • Dispersadron  C: one drop in the operative eye, four times a day for a week.
  • Artificial tears (Preservative-free): one drop in the eyes, as often as needed, ten minutes after applying the medication drops. They contribute to eye moisturizing. 

 

Eye drops Use

  • Always wash your hands before putting in the drops.
  • Shake the bottles thoroughly prior to each drop .
  • There is no preference as to which medication drop is applied first, just remember to wait 2-3 minutes between each drop.
  • You may experience a medicinal taste in the back of your throat after putting in drops, this is normal.
  • Eye drops are not applied during night time.
  • Be careful not to touch the eye with the bottle.
  • Eye drops are applied over the bandage contact lenses that have been inserted after the operation. The eye surgeon will take the lenses off the next day. If they fall out, contact us immediately.
  • Keep eye drops in a cool place, away from heat, moisture and direct sunlight.

After the procedure, your vision will be relatively blurry, as if looking through a frosty of fogged up window. This is normal and will subside within the next six to twelve (6-12) hours. Keep your eyes closed as much as possible.

On the following day, you may return to your daily activities such as reading, TV, computer or even go back to your work, if you feel comfortable.

 

Precautions

  • It is very important to pay attention to your eyes hygiene for one week after the operation.
  • Avoid rubbing, bumping, or scratching your eyes.
  • A pair of eye shields is provided in your “post-operative care kit”. The shields are to be worn at night or during naps with the pointed part of the shield pointing towards the nose. A roll of tape is included in the kit to apply the shield for subsequent nights.
  • Do not swim/ work out for one week after the operation.
  • Do not rinse your eyes with water. Wash your hair leaning backwards keeping your eyes closed like being at hairdresser’s.
  • Avoid facial cosmetics, makeup, mascara and colored contact lenses for one week after the operation.
  • Do not drive until you are confident with your vision.

 

Possible symptoms

  • foreign body sensation
  •  pain
  •  blurred vision
  • itchiness
  • lacrimation
  • redness
  • eyelid swelling
  • light sensitivity
  • headache

 

These are normal symptoms to expect after the procedure. Your eye drops, artificial tears, a painkiller and a good rest will help you through your recovery.

Eye drops schedule

  1. Vigamox: One drop in the operative eye, four times a day for ten days.
  2. Dispersadron C: One drop in the operative eye, four times a day for the 1st month.
  3. Vexol: One drop in the operative eye, two times a day for the 2nd month.
  4. Vitamin C 1000mg: take one effervescent or regular tablet daily for two months.
  5. Artificial tears (Preservative-free): One drop in the eyes, as often as needed, ten minutes after applying the medication drops. They contribute to eye moisturizing. 

If you experience mild eye pain the first 1-3 days, take 1 Lonarid N tablet every 4-6 hours as needed.

 

Eye drops Use

  • Always wash your hands before putting in the drops.
  • Shake the bottles thoroughly prior to each drop .
  • There is no preference as to which medication drop is applied first, just remember to wait 2-3 minutes between each eye drop.
  • You may experience a medicinal taste in the back of your throat after putting in drops, this is normal.
  • Eye drops are not applied during night time.
  • Be careful not to touch the eye with the bottle.
  • Eye drops are applied over the bandage contact lenses that have been inserted after the operation. The eye surgeon will take the lenses off in 3-4 days. If they fall out, contact us immediately.
  • Keep eye drops in a cool place, away from heat, moisture and direct sunlight.

 

After the operation, please keep your eyes closed, as much as possible.

 

Precautions

  • It is very important to pay attention to your eyes hygiene for ten days after the operation.
  • Avoid rubbing, bumping, or scratching your eyes.
  • A pair of eye shields is provided in your “post-operative care kit”. The shields are to be worn at night or during naps with the pointed part of the shield pointing towards the nose. A roll of tape is included in the kit to apply the shield for subsequent nights.
  • Do not swim/ work out for ten days after the operation.
  • Do not rinse your eyes with water. Wash your hair leaning backwards keeping your eyes closed like being at hairdresser’s.
  • Avoid facial cosmetics, makeup, mascara and colored contact lenses for ten days after the operation.
  • Do not drive until you are confident with your vision.
  • UV blocking sunglasses required when outdoors after surgery for two months.

 

Possible symptoms

  • foreign body sensation
  •  pain
  •  blurred vision
  • itchiness
  • lacrimation
  • redness
  • eyelid swelling
  • light sensitivity
  • headache

 

These are normal symptoms to expect after the procedure. Your eye drops, artificial tears, a painkiller and a good rest will help with your recovery.