Myopia - Hypermetropia - Astigmatism

A healthy eye's cornea, (the anterior surface of the eye) receives incoming light and focuses it directly on the retina the inner eye).

A healthy eye's cornea, (the anterior surface of the eye) receives incoming light and focuses it directly on the retina the inner eye).

What are the refractive conditions of the eye?

What are the refractive conditions of the eye?

refractive conditionMyopia

Myopia is a refractive disorder in which people with this condition do not clearly see distant objects (short-sightedness). In myopia, the eye is larger than normal. Thus, the light rays from distant objects focus in front of the retina, rather than on it, making them look turbid.

Hypermetropia

People who have hypermetropia are more likely to see objects which are at a distance more clearly than objects which are closer to them. In hypermetropia, the cornea is usually flatter and the eye is smaller than that of a healthy eye. The cornea does not refract the light properly, so the focal point is behind the retina. As a result, nearby objects look blurry. (long-sightedness)

Astigmatism

In astigmatism, both nearby and distant objects appear distorted. The cornea instead of being a perfect spherical shape usually has the shape of an ellipsoid. This results in the eye not being able to concentrate on the incoming light rays since there are multiple focul points.

Ways to deal with refractive disorders

Someone with myopia, hyperopia and/or astigmatism has three options. They can either wear eyeglasses, contact lenses, or undergo laser treatment.

The procedure for correcting the refractive error (myopia, hyperopia, astigmatism) of an eye by laser is done via the cornea of ​​the eye, that is, at the surface of the eye, in front of the pupil and the iris.

The techniques used by laser can change the curvature and consequently the force of the cornea in a very precise and specialized manner, permanently and without affecting the health of the eye. This allows the person who has been treated to see well again, without the further needing either glasses or contact lenses.

Am I a suitable candidate for refractive surgery with LASER?

Detailed pre-operative tests are performed on all candidates who are considering refractive surgery. This is intended both to determine the suitability of the eye and to select the appropriate technique so that the result of the operation is the best for the specific patient concerned.

Essential requirements for the potential candidates are:

  • that each candidate has reached the age of 18
  • their vision has been stable for at least 1 year
  • no other ophthalmological problems coexist

Once these tests have taken place then Dr. Vayianos will propose the most appropriate technique for your case.

Latest equipment in eye care

At our clinic, we have a strict protocol for screening candidates for refractive surgery. We perform various measurements in each eye, both subjective tests where the candidate determines the outcome of the tests (ocular dominance), and objective tests, where the results are given to us via machines (Autorefraction, Pupilometer, Corneal Topography with two via both Topography and Wavefront analysis, Pentacam HR, and OCT).

In addition to measuring the refractive error, other important parameters that are taken into account are:

  • The thickness of the thinner point of the cornea. This is important for the determination of the technique and is controlled by 3 different methods (OCT Pachymetry, Pentacam HR, Pachymetry and Aberrometry using the latest  equipment).
  • The smoothness not only of the anterior but also of the posterior surface of the cornea. This requires special technology (Pentacam HR and OCT cornea) which we use in all cases.
  • In the case of astigmatism, we always determine its garde and the exact axis .
  • We do a strict study of the size of the pupil's eye in both light and dark conditions, thus determining the quality of vision that a person can have after the intervention in very dark conditions. This study is aided by Topcon's high-tech ALADDIN

Does refractive surgery have possible complications?

As with any kind of surgery, there may be some complications in refractive surgery, which of course are extremely rare and manageable.

Prior to surgery, Dr. Vayianos will explain in detail these possible complications. On the day of surgery, you will be asked to sign an informed consent, as is the case with all invasive procedures.

 

Laser Types

Refractive Surgery - Laser

Refractive surgery is the terminology that refers to surgical methods which repair refractive eye disorders (myopia, hyperopia, astigmatism), by influencing and remodeling the anterior surface of the eye so that clear vision is possible. This is to relieve patients from the use of glasses and/or contact lenses.

Laser has become the most widespread type of surgery in eye care

Radial keratotomy was the initial method for refractive surgery, and played an important role in the development of refractive surgery in general. The revolutionary laser-based process, thanks to the evolution of technology and the increasing experience of refractive surgeons, provides efficiency, precision and safety.

The purpose of these interventions is generally to relieve direct dependence on eyeglasses or contact lenses, which in itself leads to better visual quality and lifestyle.

There are various techniques for refractive surgery and each candidate takes pre-operative examinations as to select a technique that is specifically appropriate for each individual.

  • Photorefractive keratectomy PRK: this method is very effective in correcting small degrees of myopia, with or without astigmatism. It is also used in cases where the cornea is relatively thin or exhibits certain peculiarities, e.g. scars or keratoconus. A very fine laser beam is applied to the surface of the cornea for the removal of the corneal surface membrane (epithelium) and then treatment with Excimer Laser is followed. At the end of the procedure, a contact lens is placed to help the epithelium heal which takes three to four days.
  • LASIK with femtosecond laser: is painless, very fast, and effective in even the most difficult of cases. It is the most widespread method for correcting myopia, astigmatism and hyperopia. It is a combination of two different lasers. PRK is first preformed, except that here the laser is not applied to the surface of the cornea but under a thin superficial "flap". In this method, the flap is formed by means of a special laser system, Femtosecond Laser. Then Excimer Laser is used to treat the refractive error.
  • LASIK Xtra: is usually used in difficult cases such as high myopia and thin cornea. It is an additional procedure in which vitamin B2 (riboflavin) and ultraviolet light (one minute duration per eye) are used after LASIK's usual surgery. Also, an additional safety valve is provided to stabilize the result.
  • VISIAN ICL: Patients who for various reasons are unable to undergo Laser therapy may undergo the procedure to place a thin lens (such as a contact lens) in front of the lens of the eye.

Surgical refractories

  • Intraoculars (IOL): Intraoculars are almost always applied to cataract surgery but depending on their dioptic strength they can correct myopia, hyperopia, astigmatism and presbyopia that existed prior to cataract surgery.
  • Lentile endoscopes: is a new method for people seeking a permanent correction of refractive errors such as the correction of high myopia of up to 20 diopters. Relatively simple in its surgical application, it has an immediate and fast effect. It is reversible if needed and one doen not need to stay overnight at the clinic. The lenticular intraoculars are intraoculars which are placed surgically in the eye, either between the cornea and the iris, or just behind the iris, similar to that of a normal contact lens on the natural lens of the eye that is not removed. It is used to correct high myopia of up to 20 diopters.
  • Eye Corrections with intracellular rings: is usually used for diseases such as keratoconus and keratectasis and in cases where the patient has only little myopia or astigmatism. It is an insertion of plastic rings onto the corneal layer as to correct its curvature.