Contact Lens & Anterior Eye
Volume 32, Issue 3 , Pages 129-132, June 2009

Comparison of corneal biomechanics in pre and post-refractive surgery and keratoconic eyes by Ocular Response Analyser

  • Sunil Shah

      Affiliations

    • Birmingham Heartlands and Solihull NHS Trust, Solihull, UK
    • Anterior Eye Group, Neurosciences Research Institute, Aston University, Birmingham, UK
    • Birmingham and Midland Eye Centre, Birmingham, UK
    • Each author states that he has no proprietary interest in the development or marketing of any instruments used.
    • Corresponding Author InformationCorresponding author at: Heart of England Foundation Trust, Lode Lane, Solihull, West Midlands, B91 2JL, UK. Tel.: +44 121 424 4456; fax: +44 121 424 5462.
    • ,
  • Mohammed Laiquzzaman

      Affiliations

    • Birmingham Heartlands and Solihull NHS Trust, Solihull, UK
    • Each author states that he has no proprietary interest in the development or marketing of any instruments used.

published online 24 February 2009.

Abstract 

Purpose

To compare biomechanical parameters measured by the Ocular Response Analyser (ORA) in the form of corneal hysteresis (CH), corneal resistance factor (CRF) and central corneal thickness (CCT) in eyes before and after excimer laser refractive surgery and keratoconic eyes.

Setting

Teaching Hospital and private eye clinic in Solihull, UK.

Methods

Prospective case comparison of 110 eyes selected for refractive surgery and 132 keratoconic eyes. The CH and CRF of each eye was measured by the ORA. The CCT was measured using ultrasonic pachymetry.

Results

The mean preoperative (pre-op) CH for the normal refractive surgery eyes was 11.4±1.9mmHg, CRF 10.0±1.6mmHg and CCT 546.5±33.0μm. Post-operatively CH was 9.2±2.1mmHg, CRF 7.6±1.8mmHg and CCT 483.1±40.8μm. The values for keratoconic eyes were 9.4±2.2mmHg, 7.7±2.6mmHg and 488.1±52.6μm, respectively. The CH, CRF and CCT decreased as the severity of keratoconic eyes increased. All these parameters showed statistically significant difference between normal eyes and keratoconic eyes. This was also the case between post-operative eyes.

Conclusion

The biomechanical parameters measured were very similar when comparing keratoconic and post-refractive surgery eyes.

Keywords: Hysteresis, Corneal resistance factor, Keratoconus, LASIK/LASEK

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PII: S1367-0484(08)00151-3

doi:10.1016/j.clae.2008.12.009

Contact Lens & Anterior Eye
Volume 32, Issue 3 , Pages 129-132, June 2009

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