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The Procedure





Laser Assisted In Situ Keratomileusis (LASIK  "flap & zap" ALK-E)

There has been a dramatic move towards LASIK, which offers fresh hope to the millions of people with poor eye sight who need to wear glasses or contact lenses.  Successful LASIK provides rapid improvement in unaided vision with little pain or discomfort and minimal use of drops following surgery.

The advantages of LASIK in providing a rapid recovery of vision allows many professional people to undertake laser refractive surgery with little break from their lifestyle. After LASIK if the refractive target has not been achieved further laser pulses can be applied after 12 weeks from the original treatment.

If there is a significant residual refractive error after the first treatment, then a flap-lift procedure can be performed to correct the remainder.

LASIK is now often performed for all myopic and hyperopic treatment but some still prefer PRK for the lower refractive changes as it has a low complication rate.  However LASIK is now the procedure of choice for much refractive surgery.


Benefits of LASIK over PRK

  • Usually minimal discomfort with LASIK. The corneal epithelium is removed with PRK but is left almost intact with LASIK

  • Post surgery vision returns within hours with LASIK, rather than weeks or months with PRK

  • Reduced incidence of corneal haze (scarring) in the long term for LASIK than PRK for high myopia

  • Less change due to healing (regression) and thus greater predictability of the correction with LASIK for high myopia or astigmatism

  • Treatment to the second eye is normally performed   simultaneously with LASIK

  • Often fewer follow-up visits required

Disadvantages of LASIK

  • Failure of the microkeratome leading to problems with the corneal flap

  • Loss or damage to the corneal flap during or after the treatment or slipping of the flap and healing off centre causing distortion and wrinkling of the cornea

  • Invasion of the surface tissue under the flap, known as "epithelial in-growth”

  • Infection of the cornea “corneal abscess” which may extend inside the eye

  • Loss of visual acuity - from scarring, wrinkling or from decentration of the LASIK flap

  • The excimer laser application is deep within the cornea and shock waves may potentially damage the cells on the inner surface of the cornea

  • Failure of the suction device to maintain suction with consequent damage to the cornea and possible aborting of the procedure mid way across the cornea

  • Retinal haemorrhage (bleeding), macular oedema, retinal tear, central retinal artery occlusion from the pressure change


    The overall significant complication rate for LASIK is of the order of 1% to 2%. 


    The frequency of re-treatment is 1% to 2% for lower myopic treatments and 6- 20 % for high myopia. Re-treatment after LASIK is generally successful but has a small risk of flap dislocation or wrinkling.

There may be contraindications for corneal refractive surgery if certain conditions are present, since there may be additional risk or a poor outcome may be involved:

  • Non-Corneal Refractive Surgery

    Extreme degrees of myopia and hyperopia cannot be successfully treated by corneal surgery and treatment requires other techniques.  

    These include implantation of an intra-ocular "phakic" lens implant. Such lenses may have a long-term risk to the cornea or lens of the eye and there may be problems with night glare and glaucoma in some cases.

    Alternatives to the use of the excimer laser have been investigated for many years including the use of infrared laser systems and implantation of rigid rings into the clear cornea of the eye. There will be a continuing debate in refractive surgery regarding the place of this technology against modern laser refractive surgery.

    The LASIK procedure explained

    The excimer laser is used to reshape the surface of the cornea

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Page last updated on Saturday, 25 June 2005 12:36:28


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