Skip to main content

Advertisement

Log in

Corneal biomechanical properties after LASIK, ReLEx flex, and ReLEx smile by Scheimpflug-based dynamic tonometry

  • Refractive Surgery
  • Published:
Graefe's Archive for Clinical and Experimental Ophthalmology Aims and scope Submit manuscript

Abstract

Purpose

To evaluate corneal biomechanical properties after LASIK, ReLEx flex, and the flap-free procedure ReLEx smile by Scheimpflug-based dynamic tonometry (Corvis ST) and non-contact differential tonometry (Ocular Response Analyzer, ORA).

Methods

Patients treated for high myopia (−10.5 to −5.5 diopters, spherical equivalent refraction) more than one year previously at Aarhus University Hospital were included. Treatments comprised LASIK (35 eyes), ReLEx flex (31 eyes), and ReLEx smile (29 eyes). A control group included 31 healthy eyes. Cornea-compensated IOP (IOPcc), corneal hysteresis (CH), and corneal resistance factor (CRF) were measured with ORA. Corneal applanation and deformation were registered with Corvis ST during an air-pulse.

Results

Multiple linear regression analysis showed that CH and CRF were significantly lower after all keratorefractive procedures compared to healthy controls (p < 0.05). No significant differences were observed in CH or CRF between the keratorefractive groups. Corvis ST showed no differences in radius at highest concavity (HC radius), time until first applanation (A1 Time), time until second applanation (A2 Time), and deflection length at highest concavity (HC deflection length) between groups. LASIK treated eyes had significantly shorter time until highest concavity than eyes treated with ReLEx smile (HC Time, p = 0.01). The A1 deflection length was significantly shorter in the keratorefractive groups compared to the healthy controls (p < 0.05).

Conclusions

Keratorefrative procedures alter the corneal biomechanical properties with regard to corneal hysteresis and corneal resistant factor. The flap-based LASIK and ReLEx flex and the flap-free ReLEx smile result in similar reduction in corneal biomechanics when evaluated by Corvis ST and ORA.

This is a preview of subscription content, log in via an institution to check access.

Access this article

Price excludes VAT (USA)
Tax calculation will be finalised during checkout.

Instant access to the full article PDF.

Institutional subscriptions

Fig. 1
Fig. 2
Fig. 3

Similar content being viewed by others

References

  1. Gazieva L, Beer MH, Nielsen K, Hjortdal J (2011) A retrospective comparison of efficacy and safety of 680 consecutive lasik treatments for high myopia performed with two generations of flying-spot excimer lasers. Acta Ophthalmol 89:729–733

    Article  PubMed  Google Scholar 

  2. Wang JC, Hufnagel TJ, Buxton DF (2003) Bilateral keratectasia after unilateral laser in situ keratomileusis: a retrospective diagnosis of ectatic corneal disorder. J Cataract Refract Surg 29:2015–2018

    Article  PubMed  Google Scholar 

  3. Geggel HS, Talley AR (1999) Delayed onset keratectasia following laser in situ keratomileusis. J Cataract Refract Surg 25:582–586

    Article  CAS  PubMed  Google Scholar 

  4. Joo CK, Kim TG (2000) Corneal ectasia detected after laser in situ keratomileusis for correction of less than −12 diopters of myopia. J Cataract Refract Surg 26:292–295

    Article  CAS  PubMed  Google Scholar 

  5. Ou RJ, Shaw EL, Glasgow BJ (2002) Keratectasia after laser in situ keratomileusis (LASIK): evaluation of the calculated residual stromal bed thickness. Am J Ophthalmol 134:771–773

    Article  PubMed  Google Scholar 

  6. Parmar D, Claoue C (2004) Keratectasia following excimer laser photorefractive keratectomy. Acta Ophthalmol Scand 82:102–105

    Article  PubMed  Google Scholar 

  7. Teichmann KD (2004) Bilateral keratectasia after laser in situ keratomileusis. J Cataract Refract Surg 30:2257–2258

    Article  PubMed  Google Scholar 

  8. Tervo TM (2001) Iatrogenic keratectasia after laser in situ keratomileusis. J Cataract Refract Surg 27:490–491

    Article  CAS  PubMed  Google Scholar 

  9. Amoils SP, Deist MB, Gous P, Amoils PM (2000) Iatrogenic keratectasia after laser in situ keratomileusis for less than −4.0 to −7.0 diopters of myopia. J Cataract Refract Surg 26:967–977

    Article  CAS  PubMed  Google Scholar 

  10. Fogla R, Padmanabhan P (2004) Bilateral keratectasia after unilateral laser in situ keratomileusis. J Cataract Refract Surg 30:2033–2034

    Article  PubMed  Google Scholar 

  11. Ambrosio R Jr, Dawson DG, Salomao M, Guerra FP, Caiado AL, Belin MW (2010) Corneal ectasia after LASIK despite low preoperative risk: tomographic and biomechanical findings in the unoperated, stable, fellow eye. J Refract Surg 26:906–911

    Article  PubMed  Google Scholar 

  12. Hjortdal JO, Vestergaard AH, Ivarsen A, Ragunathan S, Asp S (2012) Predictors for the outcome of small-incision lenticule extraction for myopia. J Refract Surg 28:865–871

    Article  PubMed  Google Scholar 

  13. Abahussin M, Hayes S, Knox Cartwright NE et al (2009) 3D collagen orientation study of the human cornea using X-ray diffraction and femtosecond laser technology. Invest Ophthalmol Vis Sci 50:5159–5164

    Article  PubMed  Google Scholar 

  14. Luce DA (2005) Determining in vivo biomechanical properties of the cornea with an ocular response analyzer. J Cataract Refract Surg 31:156–162

    Article  PubMed  Google Scholar 

  15. Ambrosio R Jr, Nogueira LP, Caldas DL et al (2011) Evaluation of corneal shape and biomechanics before LASIK. Int Ophthalmol Clin 51:11–38

    Article  PubMed  Google Scholar 

  16. Glass DH, Roberts CJ, Litsky AS, Weber PA (2008) A viscoelastic biomechanical model of the cornea describing the effect of viscosity and elasticity on hysteresis. Invest Ophthalmol Vis Sci 49:3919–3926

    Article  PubMed  Google Scholar 

  17. Vestergaard A, Ivarsen A, Asp S, Hjortdal JO (2012) Femtosecond (FS) laser vision correction procedure for moderate to high myopia: a prospective study of ReLEx(®) flex and comparison with a retrospective study of FS-laser in situ keratomileusis. Acta Ophthalmol 91:355–362

    Article  PubMed  Google Scholar 

  18. Lam AK, Chen D, Tse J (2010) The usefulness of waveform score from the ocular response analyzer. Optom Vis Sci 87:195–199

    Article  PubMed  Google Scholar 

  19. Reinstein DZ, Srivannaboon S, Archer TJ, Silverman RH, Sutton H, Coleman DJ (2006) Probability model of the inaccuracy of residual stromal thickness prediction to reduce the risk of ectasia after LASIK part II: quantifying population risk. J Refract Surg 22:861–870

    Article  PubMed  Google Scholar 

  20. Leccisotti A (2007) Corneal ectasia after photorefractive keratectomy. Graefes Arch Clin Exp Ophthalmol 245:869–875

    Article  PubMed  Google Scholar 

  21. Reinstein DZ, Archer TJ, Randleman JB (2013) Mathematical model to compare the relative tensile strength of the cornea after PRK, LASIK, and small incision lenticule extraction. J Refract Surg 29:454–460

    Article  PubMed  Google Scholar 

  22. Kirwan C, O'Keefe M (2008) Corneal hysteresis using the reichert ocular response analyser: findings pre- and post-LASIK and LASEK. Acta Ophthalmol 86:215–218

    Article  PubMed  Google Scholar 

  23. Hamilton DR, Johnson RD, Lee N, Bourla N (2008) Differences in the corneal biomechanical effects of surface ablation compared with laser in situ keratomileusis using a microkeratome or femtosecond laser. J Cataract Refract Surg 34:2049–2056

    Article  PubMed  Google Scholar 

  24. Uzbek AK, Kamburoglu G, Mahmoud AM, Roberts CJ (2011) Change in biomechanical parameters after flap creation using the intralase femtosecond laser and subsequent excimer laser ablation. Curr Eye Res 36:614–619

    Article  PubMed  Google Scholar 

  25. Agca A, Ozgurhan EB, Demirok A, et al. Comparison of corneal hysteresis and corneal resistance factor after small incision lenticule extraction and femtosecond laser-assisted LASIK: a prospective fellow eye study. Cont Lens Anterior Eye. 2013.

  26. Huseynova T, Waring GO, Roberts C, Krueger RR, Tomita M. Corneal biomechanics as a function of intraocular pressure and pachymetry by dynamic infrared signal and scheimpflug imaging analysis in normal eyes. Am J Ophthalmol. 2014.

  27. Pepose JS, Feigenbaum SK, Qazi MA, Sanderson JP, Roberts CJ (2007) Changes in corneal biomechanics and intraocular pressure following LASIK using static, dynamic, and noncontact tonometry. Am J Ophthalmol 143:39–47

    Article  PubMed  Google Scholar 

  28. Nemeth G, Hassan Z, Csutak A, Szalai E, Berta A, Modis L (2013) Repeatability of ocular biomechanical data measurements with a scheimpflug-based noncontact device on normal corneas. J Refract Surg 29(8):558–563

    PubMed  Google Scholar 

  29. Daxer A, Misof K, Grabner B, Ettl A, Fratzl P (1998) Collagen fibrils in the human corneal stroma: structure and aging. Invest Ophthalmol Vis Sci 39:644–648

    CAS  PubMed  Google Scholar 

  30. Ang M, Chaurasia SS, Angunawela RI et al (2012) Femtosecond lenticule extraction (FLEx): clinical results, interface evaluation, and intraocular pressure variation. Invest Ophthalmol Vis Sci 53:1414–1421

    Article  PubMed  Google Scholar 

  31. Landoulsi H, Saad A, Haddad NN, Guilbert E, Gatinel D (2013) Repeatability of ocular response analyzer waveform parameters in normal eyes and eyes after refractive surgery. J Refract Surg 29(10):709–714

    PubMed  Google Scholar 

  32. Vestergaard A, Grauslund J, Ivarsen A, Hjortdal J (2013) Central corneal sublayer pachymetry and biomechanical properties after refrative femtosecond laser lenicule extraction. J Refract Surg 30(2):102–108

    Article  Google Scholar 

Download references

Financial support

The study was supported by Fight for Sight, Denmark. The Pentacam HR and the Ocular Response Analyzer were kindly donated by Bagenkop-Nielsens Myopia Foundation.

Disclosure

No author has a financial or proprietary interest in any material or method mentioned. Jesper Hjortdal, MD PhD, has received travel reimbursements from Carl Zeiss Meditec.

Author information

Authors and Affiliations

Authors

Corresponding author

Correspondence to Iben Bach Pedersen.

Rights and permissions

Reprints and permissions

About this article

Check for updates. Verify currency and authenticity via CrossMark

Cite this article

Pedersen, I.B., Bak-Nielsen, S., Vestergaard, A.H. et al. Corneal biomechanical properties after LASIK, ReLEx flex, and ReLEx smile by Scheimpflug-based dynamic tonometry. Graefes Arch Clin Exp Ophthalmol 252, 1329–1335 (2014). https://doi.org/10.1007/s00417-014-2667-6

Download citation

  • Received:

  • Revised:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI: https://doi.org/10.1007/s00417-014-2667-6

Keywords

Navigation