Correcting refractive error with laser 

Not long ago, the only way to correct refractive errors was wearing prescription glasses and contact lenses. Today, however, different surgical techniques have been invented which change the shape of the cornea to correct refractive errors. A common technique is treatment by laser in which the patient's quality of vision is enhanced. These techniques include LASIK, FemtoLASIK, Photorefractive keratectomy, Epi-LASIK, and LASEK.

Note that the success rate of refractive error correction surgery largely depends on your understanding of the surgical method and expectation of your postoperative vision. Since its inception, Iran Noor Eye Hospital has performed refractive error correction with LASIK surgery with the help of experienced Iranian ophthalmologists and the most advanced LASIK surgery devices in the operating rooms of Noor Eye Hospital.

LASIK is an outpatient surgical technique used to correct hyperopia, myopia, and astigmatism. It is one of the most appropriate and quickest refractive error correction techniques. In this method, a thin cut is made on the cornea and then, at surgeon’s order, the patient looks at a flashing light above their head. At this stage, laser is aimed at the corneal surface.

FemtoLASIK is one of the most recent correction techniques for myopia, hyperopia, and astigmatism, performed by a femtosecond laser. Currently, it is mostly used in cutting the cornea during LASIK and is considered as a superior form of LASIK. The femtosecond laser has hugely evolved refractive error correction. Interestingly, every infrared femtosecond laser pulse lasts only 10 to 15 seconds, and thus adjacent areas of the cornea are not damaged.

Rapid recovery: Most of the patients can return to normal activities within one or two days. There is often no pain, and appropriate vision is obtained after 24 hours. There is greater discomfort in RK (corneal cut) and PRK (laser).

Correction of an extensive range of myopia: Myopia of about 12 diopters can be well corrected by LASIK, while using PRK (laser) for high diopters (more than 7) can lead to corneal opacity, reduced vision, and partial return of myopia. Moreover, RK surgery (corneal cut) is unable to correct more than 5 to 6 diopters.

Repeatability: This surgery can be repeated in cases of lower correction level by LASIK, by lifting the thin layer created in the first surgery and using laser again. Like the first surgery, recovery is rapid.

Long-lasting effect of the surgery: Most of the studies show that the visual acuity score stabilizes within 3 to 6 months since corneal structure is slightly changed and repaired subsequently.

Preserving the normal corneal structure: The thin layer removed is completely fixed after a few days, so that it will not be displaced by blinking or rubbing the eye. Unlike RK (corneal cut), corneal rigidity and resistance against impact are not reduced in LASIK surgery.

No opacity: Unlike PRK (laser) that is likely to cause corneal opacity in high scores, no corneal opacity is created by LASIK surgery.

No long-term need for eye drops: Unlike PRK, there is no need to control wound repair by steroid eye drops following LASIK surgery. Moreover, LASIK patients do not usually need medication for more than a week.

This surgical technique uses an excimer Laser to treat mild to severe myopia, mild to moderate hyperopia, and astigmatism. Unlike LASIK, no flap is removed in this method, and it is used for people with thin cornea or for people that because of their jobs, it is better that a flap is not created in their eyes.

It is another refractive error correction technique which is very similar to PRK. In fact, it is an alternative technique for people with thin cornea. A particular type of microkeratome, called epikeratome, is used in this method. It has the advantage of creating very thin corneal cuts compared to microkeratome. Other stages are similar to LASIK.

This method is similar to LASIK and is used to treat myopia, hyperopia, and astigmatism. This technique is used for people with a thin cornea. In this method, the corneal surface layer or corneal epithelium is softened by an alcoholic solution and then removed to expose the cornea to laser radiation. Afterward, the epithelial layer is returned to its original place.

  1. Minimum age of 18 years
  2. No change in the visual score for at least one year
  3. No unrealistic expectations of the surgery
  4. No uncontrolled diabetes
  5. No connective tissue disorders
  6. No history of corneal herpes simplex
  7. No intraocular inflammation
  8. No glaucoma or cataract
  9. Not using certain medications such as Roaccutane.
  10. No pregnancy or breastfeeding

  1. Washing eyelids and eyelashes the night before surgery
  2. No makeup 48 hours prior to surgery
  3. Wearing light and comfortable clothing on the day of surgery
  4. Not wearing perfumes on the day of surgery
  5. Not using contact lenses 48 hours before surgery
  6. Taking tranquilizers in case of anxiety


- Dry eye

-Glaring lights


-Reduced night vision

-Reduced clear vision

-Sensitivity to light

Probable (uncommon)


-Corneal infection

-Irregular astigmatism

-Loss of vision

-Regression of the initial effects of surgery

Laser refractive surgery is quick and painless due to the measures taken by the medical team of Tehran-Iran Noor Eye Hospital. Your cooperation has a vital role in achieving a satisfactory outcome. Therefore, be calm and follow the ophthalmologist's instructions and the following points during surgery:

• Watch the blinking red or green light during surgery and do not move your eyes or head

• Depending on the type of laser used, laser surgery usually takes 10 seconds or less than a minute. Therefore, do not move your eyes while you still hear the sound of the laser

• Do not worry about blinking because your eyelids are kept open by a device. To prevent an unpleasant feeling during surgery, do not frown nor press your eyelids

• Keep your hands away from the surgery site because they cause contamination

• The first postoperative appointment is 24 hours after surgery.

• Visit your ophthalmologist at regular intervals in the first six months.

• The ophthalmologist examines the vision and condition of the eyes in the first visit.

• Avoid wearing contact and cosmetic lenses for at least three months after surgery.

• Do not use lotions, creams, or make-up around the eye for at least three days or until your physician allows you.

• Refrain from aggressive sports such as boxing, football, and karate for at least 10 weeks.

• Do not rub or scratch the eyes in the first few weeks after surgery.

• Fluctuation in vision is likely in the first few months after surgery. Vision stabilization may take 3-6 months, and you may experience impaired driving at night, glaring lights in the visual field, and aura in this period.

• To determine the need for re-surgical procedure, it should be waited until the vision is fixed, during two consecutive visits and at least 3 months.

In case of severe pain on the first night, follow these points for treatment:

• Do not worry.

• Take more analgesic.

• Rest in a semi-dark room.

• Use ice compress with a towel or a dry refrigerated cloth.

• Put in eye drops only by pulling down the lower eyelid.

• Take a shower on the second day after LASIK, and after epithelial repair and removal of the bandages, which takes 3-5 days, in PRK, LASEK, and Epi-LASIK surgeries.

• Prevent water from entering the eye in the first few days.

• Use baby shampoo for washing the eyes.

• Use dry ablution (tayammum) instead of wet ablution in the first few days.

• Do not watch TV, read, work with computers, or do other activities that make your eyes tired. However, these activities do not damage your eyes or weaken them again.

• Do not worry about vision fluctuation, slight burning, and headache in the first few weeks.

• Use eye drops and other prescribed medications.

Is preoperative condition of the patient's vision likely to return after surgery?

What causes itching of the eye after surgery?

Does climate affect the quality of LASIK surgery?

What is the best age and visual acuity score for the right candidate for LASIK surgery?

What is the right visual acuity score for LASIK surgery?

Does "dry eye" affect the outcome of LASIK surgery?

I have Keratoconous. Can I undergo LASIK surgery?

Is Lasik dangerous for lactating mothers?

What are the advantages of FEMTO-LASIK surgery?




Is preoperative condition of the patient's vision likely to return after surgery ?

This happens very rarely. Today, with the advances in ophthalmology and increased precision of devices, LASIK success rate is very high, and there is no need for concern.

What causes itching of the eye after surgery?

There is only one reason for the eyes to itch after LASIK surgery, and that is foreign body sensation. Your ophthalmologist administers artificial tear drops for this complication. This is more frequently seen in LASIK than in LASEK and PRK.

Does climate affect the quality of LASIK surgery?

Weather condition has no effect on but it may cause corneal opacity in LASEK and PRK in people exposed to intense sunlight. It is better to prevent this problem. People living in hot climates must wear prescription sunglasses during hot periods of the year so that UV rays cannot affect their eyes.

What is the best age and visual acuity score for the right candidate for LASIK surgery?

The minimum age for LASIK surgery is 18 years. The patient should have a constant visual acuity score over the last year. It should be noted that for patients with visual acuity scores from 1 to 9, LASIK can be performed for refractive correction.

What is the right visual acuity score for LASIK surgery?

Myopia, up to 10

Hyperopia, up to 6

Astigmatism, up to 4

Please note that these scores are different for different people, according to the cornea thickness.

Does "dry eye" affect the outcome of LASIK surgery?

Severe dry eye can cause some problems during and after surgery. Therefore, if you have symptoms of dry eye and are going to undergo LASIK surgery, please consult an ophthalmologist. Note that this is highly important to your health and vision.

I have keratoconus. Can I undergo LASIK surgery?

No. LASIK, LASEK, or PRK surgery cannot be performed on people with keratoconus because these surgeries make the cornea thinner, which exacerbates keratoconus.

Is LASIK dangerous for lactating mothers?

No, this surgery does not cause any problems for mothers during lactation and does not cause any complication for infants. However, sleep disturbance and tiredness may occur in the first few days after surgery, but these are temporary and will be resolved in a short period afterward.

What are the advantages of FEMTO-LASIK surgery?

In addition to all features of LASIK surgery such as quick visual recovery, quick pain relief, and quick return to daily life, FEMTO-LASIK is more precise and has fewer complications than LASIK. Lasik and FEMTO-LASIK are currently used in the most advanced ophthalmic centers in the world, and also in Tehran-Iran Noor Eye Hospital. Please note that an ophthalmologist can recommend the best technique.

If you have any further question, please contact our colleagues at Tehran-Iran Noor Eye Hospital, and receive your answers on our website: