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ORA Waveform Analysis of Corneal Biomechanical Changes after Clear Cornea Phacoemulsification

ORA Waveform Analysis of Corneal Biomechanical Changes after Clear Cornea Phacoemulsification. Bruno Valbon , Ana Caiado, Ricardo Louzada, Renato Ambrosio Jr *.

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ORA Waveform Analysis of Corneal Biomechanical Changes after Clear Cornea Phacoemulsification

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  1. ORA Waveform Analysis of Corneal Biomechanical Changes after Clear Cornea Phacoemulsification Bruno Valbon, Ana Caiado, Ricardo Louzada, Renato Ambrosio Jr *. Purpose : To study corneal biomechanical changes after clear cornea cataract surgery and to correlate with corneal thickness andcorneal tomographic parameters. Rio de Janeiro – Brasil 2010 * Dr. Ambrosio is a consultant to Oculus and in the speaker bureau for Reichert, Alcon and Allergan

  2. ORA Waveform Analysis of Corneal Biomechanical Changes after Clear Cornea Phacoemulsification • Methods: • 12 eyes from 11 patients who had uneventful clear cornea phacoemulsification and foldable IOL implantation were included. • Corneal tomography based on a rotating Scheimpflug camera (Oculus Pentacam) and corneal biomechanical properties measurements by the ORA (Ocular Response Analyzer – Reichert) were performed preoperatively and in the first day (D1). • Central corneal thickness (CCT) and Ambrósio’s pachimetric progression indices from the Pentacam were correlated with ORA waveform-derived parameters. • The Wilcoxon signed-rank test was used to evaluate if each variable for the comparisons of differences between measurements. • Pachimetric Parameters (TP,RPI Min, RPI Mid, RPI Max, ART- Min, ART-Mid and ART-Max) were correlated with ORA waveform-derived parameters (IOPg, IOPcc, CRF, CH, aindex, p1area, uslope2, dive1, path2, mslew1, mslew2, p1area1, uslope11, h21, path11 and path21) • The correlations were evaluated with Spearman rank correlation. A P value lower than 0,05 was considered statistically significant. Valbon B., Caiado A., Louzada R., Ambrosio Jr., R

  3. ORA Waveform Analysis of Corneal Biomechanical Changes after Clear Cornea Phacoemulsification Pré-op D1 D7 • Pentacam Ambrósio’spachimetric progression indices ( automatically obtained from index LOAD) : • TP (Thinnest Point) • RPI Min, RPI Mid, RPI Max • 3) ART- Min, ART-Mid and ART-Max * ART (Ambrósio’s Relational Thinnest ): ART Min=TP/RPI Min; ART Mid=TP/RPI Mid; ART Max=TP/RPI Max D0 Valbon B., Caiado A., Louzada R., Ambrosio Jr., R

  4. ORA Waveform Analysis of Corneal Biomechanical Changes after Clear Cornea Phacoemulsification DESCRIPTION OF ORA WAVEFORM PARAMETERS Original ORA Waveform Parameters • Original parameters all Pressure and CDS associated • (CDW - corneal deformation waveform) • IOPg - Goldmann correlated IOP (P1+P2)/2 • IOPcc - corneal compensated IOP (P2 - 0.43*P1) • CH - corneal hysteresis (P1 - P2) • CRF - corneal rsistance factor (P1 - 0.7*P2) Categories of ORA Waveform Parameters • Pressure associated - 4: IOPg, IOPcc, CH, CR • Areas - 4: area1, area2, area11, area21 • Heights - 4: h1, h2, h11, h21 • Widths - 4: w1, w2, w11, w21 • Aspect ratios -4: aspect1, aspect2, aspect11, aspect21 • Slopes - 8; uslope1, dslope1, uslope2, dslope2, etc • Slew rates - 4: slew1, slew2, mslew1, mslew2, etc • Paths - 4, path1, path2, path11, path21 • Irregularity - 2: aindex, bindex • Dive - 2: dive 1, dive2 • High Frequency 1: aplhf • Waveform Score 1: WS Valbon B., Caiado A., Louzada R., Ambrosio Jr., R

  5. ORA Waveform Analysis of Corneal Biomechanical Changes after Clear Cornea Phacoemulsification h1, h2, w1, w2, height - from lowest to highest point in peak width - at the “base” of peak region p1area, p2area area of peak 1, peak 1 uslope1, uslope2 rate of increase from BASE to PEAK PEAK PEAK h1 uslope 1 Uslope 2 w1 25% point BASE 25% point BASE mslew 1,mslew 2 maximum single increase in the rise of peak 1,2 longest continuous line w/o a break dive1, dive2 backside of “downslope” of peak1, peak2 absolute value of peak from peak 1, peak 2 until the first break aindex, bindex “smoothness” of peak 1, peak 2 number of breaks in the peak or how many times the peak changes direction PEAK aindex mslew 1 Dive 1 mslew 2 FIRST BREAK 25% point 25% point BASE Valbon B., Caiado A., Louzada R., Ambrosio Jr., R

  6. ORA Waveform Analysis of Corneal Biomechanical Changes after Clear Cornea Phacoemulsification Results: • 12 eyes of 11 patients were studied. • Table 1 show statistically significant differences in the variables from Pre-op and D1. • Tables 2 and 3 provide the data on the statistically significant correlations between pachymetric and biomechanical parameters for the Pre-op and D1. • An increase in corneal thickness was observed in all cases in the first day. • Edema was associate with a lower pachymetric progression. • An opposite phenomenon was observed for biomechanical parameters. There was a significant decrease of biomechanical parameters in the first day. Valbon B., Caiado A., Louzada R., Ambrosio Jr., R

  7. Table 1: Comparisons of differences between measurements Pre-op and D1

  8. ORA Waveform Analysis of Corneal Biomechanical Changes after Clear Cornea Phacoemulsification Correlations with statistically significant differences Tables 2 and 3 Valbon B., Caiado A., Louzada R., Ambrosio Jr., R

  9. ORA Waveform Analysis of Corneal Biomechanical Changes after Clear Cornea Phacoemulsification Graphics - Correlations with statistically significant differences Valbon B., Caiado A., Louzada R., Ambrosio Jr., R

  10. ORA Waveform Analysis of Corneal Biomechanical Changes after Clear Cornea Phacoemulsification Graphics - Correlations with statistically significant differences Valbon B., Caiado A., Louzada R., Ambrosio Jr., R

  11. ORA Waveform Analysis of Corneal Biomechanical Changes after Clear Cornea Phacoemulsification Conclusions: Corneal edema after cataract surgery is related to a significant attenuation in the thickness profile (lowering of RPI Mid and RPI Max) and with a significant decrease in corneal biomechanical parameters measured by the ORA (including CH and CRF). Aindex was the best waveform-derived parameter and CCT, TP of the most significant pachimetric parameters (Wilcoxon). There was a trend for inverting the direction of the correlations between pachymetric and biomechanical parameters from Pre-op and D1. The most important ones were: ART Min x dive1: 0.69 in Pre-op and -0.24 in D1; TP x p1area1 : -0,2671 in Pre-op and 0,1086 in D1; RPI Min x CRF : 0,1130 in Pre-op and -0,1634 in D1. This study demonstrates there is an inverted correlation between thickness parameters and corneal biomechanical properties in the presence of corneal edema. There is a trend to return to the normal pre-operative values and similar correlations as the Pre-op up to 1 month post-operatively Valbon B., Caiado A., Louzada R., Ambrosio Jr., R

  12. ORA Waveform Analysis of Corneal Biomechanical Changes after Clear Cornea Phacoemulsification ORA Waveform Analysis of Corneal Biomechanical Changes after Clear Cornea Phacoemulsification Bruno Valbon, MD Ana Laura C. Canedo, MD Ricardo Louzada, MD Renato Ambrósio Jr., MD, PhD valbonbruno@ig.com.br

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