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Marcony R. Santhiago, Renato Ambrosio, Jr., William J. Dupps, Jr., David Smadja, Edgar M. Espana, Steven E. Wilson; Lack Of Influence Of Corneal Thickness On Biomechanical Waveforms And How That Impact In Distinguishing Candidates For Lasik Or Prk. Invest. Ophthalmol. Vis. Sci. 2012;53(14):6788.
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© ARVO (1962-2015); The Authors (2016-present)
To investigate the performance of thirty-seven Biomechanical Waveforms (WF), Corneal Hysteresis (CH), Corneal Resistance Factor (CRF) in distinguishing patients who are candidate for LASIK or PRK and their correlation with central corneal thickness (CCT).
In this retrospective randomized clinical study, four-hundred eyes of 400 refractive surgery patients who presented for a refractive surgery screening were enrolled. Eyes that had previous refractive or intraocular surgery, or any ocular diseases, such as corneal opacity or irregularity, dry eye, amblyopia, anisometropia, glaucoma, or retinal abnormalities, were excluded. The main outcomes monitored were age, pre-operative spherical equivalent on manifest refraction (MRSE), ultrasonic pachymetry (USP), topographic parameters (keratometry values) and biomechanical parameters (WFs, CH and CRF).
Among the Thirty-seven biomechanical waveforms, seven were statistically significant lower in the PRK-candidate group compared to LASIK group. There was a trend in CH to be lower in the PRK-candidate group. There was a weak correlation between CCT and all the seven waveform parameters (fig.1 and fig. 2) Aspect 1 (r = -0.064), Up Slope 1 (r = -0.027), Height 1 (r = -0.035), Dive 1 (r = -0.088), slew 1 (r = -0.043), and Aspect 1-50% (r = -0.063) and Height 1-50% (r = -0.035). CH and CRF showed decreasing trends as the CCT decreases with high-moderate correlation.
Parameters Aspect 1, Up Slope 1, Height 1, Dive 1, slew 1, and Aspect 1(50) and Height 1(50) showed ability to distinguish LASIK and PRK-candidate groups and no significant correlation with CCT. Supported by Research to Prevent Blindness, New York, NY
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