Refractive surgery (LASIK-PRK-FemtoLasik)

To be able to see objects clearly, the light waves and the image of the objects must be focused on the retina after passing through the cornea and lens. The images formed on the retina are transmitted to the brain by the optic nerve and so they can be seen. Refractive errors occur when the eye fails to focus the light waves properly and accurately, therefore, the image is not completely focused on the retina and thus the image will be blurred

Types of refractive errors

Nearsightedness or Myopia

In this abnormality due to the longer anterior-posterior diameter of the eyeball or increased corneal curvature, the image of objects is formed in front of the retina and you have trouble seeing distant objects. A significant risk in this disorder, especially in severe myopia, is retinal detachment

Farsightedness or Hyperopia

In this disorder which is caused by shortening of the anterior-posterior diameter of the eyeball or decreased corneal curvature, the visual image is focused behind the retina. One sees both near and distant objects blurry, but blurred vision at near objects is more intense than the blurred vision at far objects. This disorder is worsened by aging and decreasing the power of lens adaptation


At a young age, the lens of the eye is extremely flexible and its diameter changes easily to see far and near objects. After the age of 40, the lens becomes harder and loses its adaptability, As a result, one is no longer able to read and do things from near distance. This disorder is called Presbyopia


Astigmatism is a very common disorder and most people have it to some degree. The natural cornea is smooth and curved, and its curvature is the same in all meridians. Astigmatism usually occurs when the corneal surface has an asymmetric curvature (the cornea is irregularly shaped). In this case due to the inappropriate refraction of light in different parts of the cornea, the images are not focused precisely and regularly on the retina and objects appear to be more blurred than normal at all distances far or near


Corrective Techniques of Refractive Errors

Eyeglasses: using eyeglasses is the easiest method of correction. Replacing the number of glasses is easy; it also protects the eyes from sunlight

Contact Lenses: there are different types of contact lenses available currently. Choosing the right contact lenses depends on the type of refractive error, lifestyle, and routine activities of each person. Contact lenses and glasses can help correct vision by focusing light on the retina

Common Refractive Surgery Methods

LASIK: LASIK is a combination of microscopic and excimer refractive laser surgery used for the correction of myopia, hyperopia, and astigmatism. In LASIK, using a specialized device called a microkeratome, a very thin tissue of the cornea is cut. The excimer laser is irradiated to the underlying part of this tissue and then restored to its original location. After a few minutes, the layer adheres to its position and there is no need for stitches

Femto-LASIK: FemtoLasik is one of the newest corrective methods of myopia, hyperopia and astigmatism and it’s the latest innovation in refractive error correction in which a corneal flap is created using a femtosecond laser. In terms of the surgical procedure, it is very similar to LASIK. The only yet important difference between both methods is how the flap is created. In fact, FemtoLasik is an advanced method of LASIK in which, instead of the microkeratome, a laser is used to create the flap. In addition to providing all the features of LASIK surgery including quick visual recovery, pain relief and the possibility of a quick return to daily routine, considering the fact that all the procedure is done with a laser and there is no need for microkeratome, FemtoLasik brings unparalleled accuracy and health

PRK: In PRK, the corneal epithelium (the outermost layer of the cornea) is removed and the corneal surface is reshaped using an excimer laser to correct refractive errors

LAZEK:  LASEK method is a modified type of PRK. Ophthalmologist uses an alcoholic solution to remove the corneal epithelium layer. The excimer laser is then applied to the cornea and the epithelium layer is reattached to its original position. This method is not much popular and virtually is replaced by PRK