Refractive Laser Surgery

  • Melanie Corbett
  • Nicholas Maycock
  • Emanuel Rosen
  • David O’Brart


All corneal refractive procedures correct myopia by flattening the central cornea and correct hyperopia by steepening it. In procedures removing tissue from the superficial or anterior cornea (e.g. keratectomy and excimer or femtosecond laser procedures), topography can underestimate the change in corneal power because the algorithms assume a normal corneal thickness when calculating the total corneal power.

Preoperative topography is valuable in screening for corneal disease, planning treatments and guiding tailored laser techniques. The difference between the immediate postoperative map and the preoperative map shows the treatment that has been achieved and any problems with it, such as decentration of the treatment zone.

The difference between a later postoperative map and the immediate map shows changes that have resulted from the healing response (e.g. aggressive healing post-PRK causing regression), epithelial ingrowth beneath a LASIK flap or progressive ectasia if too little tissue has been left in the corneal bed.

Laser thermokeratoplasty corrects low degrees of hyperopia by inducing thermal contraction of collagen fibres in a ring of spots around the midperiphery of the cornea, causing central corneal steepening.


Corneal topography Refractive surgery Myopia Hyperopia Astigmatism Screening Corneal stability Corneal ectasia Keratectomy Excimer laser Femtosecond laser Topography-guided laser Decentred treatment zone Regression Epithelial ingrowth Ectasia Laser thermokeratoplasty 


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Copyright information

© Springer Nature Switzerland AG 2019

Authors and Affiliations

  • Melanie Corbett
    • 1
  • Nicholas Maycock
    • 2
  • Emanuel Rosen
    • 3
  • David O’Brart
    • 4
  1. 1.Imperial College Healthcare NHS TrustLondonUK
  2. 2.University Hospital Coventry and WarwickshireCoventryUK
  3. 3.ManchesterUK
  4. 4.Department of OphthalmologySt. Thomas HospitalLondonUK

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