Laser assisted in situ keratomileusis (LASIK)

  • LASIK is a surgery to correct refractive error or operation to remove spectacle.
  • special type of cutting laser is used to precisely change the shape of the dome-shaped clear tissue at the front of your eye (cornea) to improve vision.
  • In the eye with normal vision the cornea bends the light rays to focus the image of objects on the retina (most backward part of eye that sense the light of image and give that sensation to brain to identify object) to see the things.
  • But in eye with minus(myopic), plus(hypermetropic) or astigmatic (cross) power this focusing mechanism is incorrect.
  • so that in LASIK operation, with the specific laser eye surgeon can reshape the cornea to get the correct focusing system to see the things clearly without use of spectacle or contact lens.

Investigation procedure

  • Routine OPD examination.
  • Corneal scans: pentacam reports to check patients corneal thickness and anterior (outer) and posterior(inner most) surface shape.
  • Dryness tests.
  • Eye pressure (IOP).
  • Full (till borders) retina examine.

Patient criteria

  • Patients age is above 18 years.
  • Same spectacle power since last 12 months.
  • Patient is self motivated because it is fairly cosmetic surgery,the patient’s like.
  • In routine check up no eye’s pathology or corneal pathology detected.
  • In pentacam reports any corneal surface irregularities or thinning detect and/or the corneal thickness is less that 450 micron than LASIK is fairly contraindication.


  • A mechanical surgical tool called a microkeratome or a femtosecond laser is used to create a thin, circular flap in the cornea. The surgeon then folds back this hinged flap to access the underlying cornea (called the stroma).
  • An excimer laser is used to reshape the corneal stroma. This highly specialized laser uses a cool ultraviolet light beam to remove microscopic amounts of tissue from the cornea, ultimately flattening the cornea.
  • The corneal flap is laid back in place, where it sticks to the corneal stroma without stitches.

Advances in LASIK

  1. Customized (C) LASIK Or custom wavefront LASIK
    • C LASIK adds precision and personalisation by using advance wavefront technology to evaluate uniqueness of your eye.
    • Conventional LASIK surgery attempts to recreate the vision correction that your eyeglass power provides.
    • Custom LASIK uses much more detailed information than a conventional eyeglasses prescription to program the excimer laser that reshapes your eye during the vision correction procedure.
    • For example, If your eyeglass proscription is -2.25 D detected in OPD examination. the conventional LASIK excimer laser programmed with 2.25 D and that reshape your cornea with the 2.25D laser treatment.
    • But, in the C LASER your eye power is rechecked with wavefront laser which have 0.01D power accuracy instead of 0.25 D power and the wavefront laser get 2.08D power than the excimer laser is programmed with this accurate power and according to that patient’s cornea is reshaped.
  2. Femto-LASIK
    • Also known as ‘all laser LASIK’ or ‘No blade LASIK’
    • Femto laser destruct the corneal tissue, The higher frequency of laser allows reduced flap creation time and lower energy per pulse leading to a smoother corneal stromal bed.
    • It is the technique in which the corneal flap is made with femtosecond laser and excimer laser applies to reshape the cornea.
    • Custom femto-LASIK (C F LASIK) is the laser technique in which customise LASIK with use of femtosecond laser for corneal flap.
Procedure of flap creation with femto laser
  • The suction ring is centered over the pupil ( or center part of cornea)and suction is applied once proper centration of the ring has been ensured and verified.
  • Multiple laser pulses are applied next to each other to create a cleavage plane and ultimately the LASIK flap.
  • Suction is then released. A spatula is carefully passed across the flap starting at the hinge and sweeping inferiorly to lift the flap for excimer laser application.
Advantage of femto-laser
  • Reduce some irregularities to creat flap with microkeratoms.
  • Decrease the flap thickness so that remaining corneal thickness after LASIK is higher.
  • Because of the thin flap applicable in thin corneas and high refractive errors.