Posterior Corneal Changes after Photorefractive Keratectomy (PRK) in Pa-tient with Myopia Greater than 6 Diopters

Document Type : Original Article(s)

Authors

1 Professor, Department of Ophthalmology, School of Medicine, Isfahan University of Medical Sciences, Isfahan, Iran.

2 Assistant Professor, Department of Ophthalmology, School of Medicine, Isfahan University of Medical Sciences, Isfahan, Iran.

3 Resident, Department of Ophthalmology, School of Medicine, Lorestan University of Medical Sciences, Lorestan, Iran.

4 Ophthalmologist, Department of Ophthalmology, School of Medicine, Shahrekord University of Medical Sciences, Shahrekord, Iran.

Abstract

Background: This study aimed to evaluate the changes of posterior corneal curvature after photorefractive keratectomy (PRK) in patient with myopia greater than 6 diopters.Methods: The study was conducted on 107 eyes of 57 patients with the preoperative spherical equivalent refractive error of at least minus six diopters. Subjects underwent PRK for treatment of myopia or myopic astigmatism and were followed 4 months later to evaluate their refractive error. The posterior corneal curvature was evaluated by orbscan II topography preoperatively and 4 months after PRK.Finding: The diameter of posterior corneal best-fitted sphere (BFS) in 3, 5, 7 and 10 millimeter zones before surgery was 6.089 ± 0.2666, 6.137± 0.253, 6.299 ± 0.268, and 6.506± 0.312 millimeters respectively and after surgery these values had changed to 5.673± 0.362, 5.809± 0.341, 6.056± 0.309, and 6.347± 0.334 millimeters respectively.Conclusion: PRK for treatment of high myopia makes significant changes in the diameter of all measured zones of posterior cornea. The amount of alteration changed with regard to the selected zone, with the maximum effect in 3 and minimum effect in 10 millimeter zones.  

Keywords

References

  1. Thomas J, Gregory L, Louis B. 2007-2008 Basic and Clinical Science Course Section 13: Refrac-tive Surgery. San Francisco, California: Ameri-can Academy of Ophthalmology; 2007.
  2. Cairns G, McGhee CN. Orbscan computerized topography: attributes, applications, and limita-tions. J Cataract Refract Surg 2005; 31(1): 205-20.
  3. Stulting RD, Balch K, Carr JD, Walter K, Thomp-son KP. Complications of LASIK. Invest Oph-thalmol Vis Sci 1997; 38: S231.
  4. Hashemi H, Mehravaran S. Corneal changes after laser refractive surgery for myopia: com-parison of Orbscan II and Pentacam findings. J Cataract Refract Surg 2007; 33(5): 841-7.
  5. Seitz B, Torres F, Langenbucher A, Behrens A, Suarez E. Posterior corneal curvature changes after myopic laser in situ keratomileusis. Oph-thalmology 2001; 108(4): 666-72.
  6. Twa MD, Roberts C, Mahmoud AM, Chang JS, Jr. Response of the posterior corneal surface to laser in situ keratomileusis for myopia. J Cata-ract Refract Surg 2005; 31(1): 61-71.
  7. Kamiya K, Oshika T, Amano S, Takahashi T, Tokunaga T, Miyata K. Influence of excimer la-ser photorefractive keratectomy on the posterior corneal surface. J Cataract Refract Surg 2000; 26(6): 867-71.
  8. Pallikaris IG, Kymionis GD, Astyrakakis NI. Corneal ectasia induced by laser in situ kera-tomileusis. J Cataract Refract Surg 2001; 27(11): 1796-802.
  9. Randleman JB, Russell B, Ward MA, Thompson KP, Stulting RD. Risk factors and prognosis for corneal ectasia after LASIK. Ophthalmology 2003; 110(2): 267-75.
  10. Sharma N, Rani A, Balasubramanya R, Vajpayee RB, Pandey RM. Posterior corneal topographic changes after partial flap during la-ser in situ keratomileusis. Br J Ophthalmol 2003; 87(2): 160-2.
  11. Miyata K, Kamiya K, Takahashi T, Tanabe T, Tokunaga T, Amano S, et al. Time course of changes in corneal forward shift after excimer laser photorefractive keratectomy. Arch Oph-thalmol 2002; 120(7): 896-900.
  12. Stakheev AA, Balashevich LJ. Corneal power determination after previous corneal refractive surgery for intraocular lens calculation. Cornea 2003; 22(3): 214-20.
  13. Wang Z, Chen J, Yang B. Posterior corneal sur-face topographic changes after laser in situ kera-tomileusis are related to residual corneal bed thickness. Ophthalmology 1999; 106(2): 406-9.
  14. Prisant O, Calderon N, Chastang P, Gatinel D, Hoang-Xuan T. Reliability of pachymetric measurements using orbscan after excimer re-fractive surgery. Ophthalmology 2003; 110(3): 511-5.
  15. Chakrabarti HS, Craig JP, Brahma A, Malik TY, McGhee CN. Comparison of corneal thickness measurements using ultrasound and Orbscan slit-scanning topography in normal and post-LASIK eyes. J Cataract Refract Surg 2001; 27(11): 1823-8.
Journal of Isfahan Medical School
Volume 29, Issue 126 - Serial Number 126
January and February 2011
Pages 49-55

Files

History

  • Receive Date: 21 November 2010
  • Revise Date: 23 May 2024
  • Accept Date: 06 April 2022

Share

How to cite

Statistics