Resumen de Corneal biomechanics after refractive surgery: A comparison between surgical techniques

Carlos Palomino Bautista, Alfredo Castillo, José Angel Cristóbal Bescós, María Ángeles del Buey Sayas, David Carmona González

• PURPOSE: To compare the effect of PRK, Lasik and femtosecond Lasik (fLasik) on the biomechanical properties of the cornea.

  METHODS: 120 eyes from subjects candidates for refractive surgery (75 men, 45 women, mean age 30±7 years of age) divided into three groups (PRK, Lasik and fLasik) were examined using the Ocular Response Analyzer (ORA). Corneal hysteresis (CH) and Corneal Resistance Factor (CRF) values were obtained before and after surgery.

  RESULTS: Average preop CH values were 10.45±1.09, 10.39±1.50 and 11.03±1.20 mmHg changing to 7.63±1.85, 7.37±1.71 and 8.83±1.44 mmHg after the surgery for the PRK, Lasik and fLasik groups respectively. A greater variability was found for both CH and CRF parameters in the PRK group, although not significantly (p>0.1). Variation was significantly greater after Lasik than fLasik (p<0.05).

  CONCLUSION: The least residual stromal bed the greater variation in both CH and CRF occurs, hence the greater risk of secondary keratectasia. The fLasik group maintains corneal biomechanics after the surgery better that the other groups studied, which probably accounts for the better predictability of the clinical outcomes.