Low_resolution_Thesis_CDD_221009_public - Visual Optics and ...

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$XXX Congress of the European Society of Cataract and Refractive ...$

CHAPTER 3 Ablation efficiency factor 1.1 1 0.9 0.8 Experimental (PMMA) Experimental (Cornea) Theoretical (PMMA) Theoretical (Cornea) 0.7 -3 -2 -1 0 1 2 3 Radial coordinate (mm) Fig. 3.6. Ablation efficiency factors obtained experimentally (black) for PMMA and cornea, compared with theoretical predictions using Jiménez et al’s equations (Jimenez et al., 2002) for PMMA and cornea respectively. Data for PMMA are represented in thick lines and for the cornea in thin lines. 3.4.4. Post - operative asphericities on PMMA Figure 3.7 shows postoperative asphericities estimated directly from the elevation maps of PMMA spherical surfaces (red circles), for different spherical corrections (the values indicate nominal corrections on the cornea, see Fig. 3.1 (b) for the equivalent corrections on PMMA). We found a systematic increase of asphericity in all the surfaces tested, the larger the correction the larger the increase. The graph also plots the predicted asphericities using the experimental ablation efficiency factor found in this study (orange diamonds) and the theoretical efficiency factor (blue triangles) proposed by Jimenez et al. (Jimenez et al., 2002), calculated with the values corresponding to PMMA material. The predicted ablation pattern is the result of direct subtraction of the experimental ablation pattern measured on flat surfaces multiplied by the efficiency factor considered from a spherical surface of 8 mm-radius. The asphericities without considering efficiency effects (ablations on flat surfaces computationally applied to the spherical surfaces) are also shown (green diamonds). Without efficiency effects, the measured ablations have asphericities close to zero (- 0.03±0.1, mean and standard deviation), and no change with correction. We found experimentally a significant increase of asphericity that can be entirely attributed to reflection losses and non-normal incidence. The mean asphericity of ablated PMMA spheres was 0.89 ±0.76. The asphericity predictions using the ablation profile from flat surfaces and the experimental efficiency factor agree well (0.93±0.37) with those obtained directly from experimental elevation maps on ablated PMMA spheres. For the 12-D sphere used in the calculation of the experimental efficiency factor, the coincidence is perfect, as expected. The theoretical efficiency factor predicts a mean increase in asphericity of 0.33±0.18, that is, 37% of the increase found experimentally. 110
REFRACTIVE SURGERY PMMA MODEL 3 2 Measured spheres With experimental efficency factor With theoretical efficency factor No efficiency effects (fat surfaces) Asphericity 1 0 -1 0 3 6 9 12 15 Correction (D) Fig. 3.7. Postoperative corneal asphericities of ablated PMMA surfaces as a function of nominal (on cornea) refractive correction, as measured directly on ablated spherical surfaces -red circles-. The figure also shows the predicted asphericity after direct subtraction of the experimental pattern measured on flat surfaces (non affected by efficiency factor) -green diamonds- as well as subtraction of this pattern multiplied by the experimental -orange diamonds- and theoretical -blue triangles- efficiency factors for PMMA. Pre-operative spherical surfaces had radii of curvature of 8-mm. 3.4.5. Post - operative asphericities on cornea Our predictions of corneal asphericity using the experimental ablation pattern (actual profile programmed in the laser system) and our experimental estimates of K cornea can be compared directly to data on real patients. Figure 3.8 shows postoperative clinical asphericities compared with predicted corneal asphericities as a function of spherical correction. Clinical asphericities (open triangles) were measured in patients treated with standard refractive surgery from a previous study in our laboratory (Marcos et al., 2001a), with an identical laser operated by the same surgeon. Predicted asphericities were calculated from experimental data, for a typical preoperative cornea of radius 7.8 and asphericity -0.2. To simulate the postoperative cornea, the ablation measured in flat surfaces is multiplied by the PMMA-cornea correction factor and by the ablation efficiency factor K cornea , and then directly subtracted from the preoperative cornea. Predictions without considering efficiency effects (green diamonds) show practically no change of corneal asphericity with ablation (-0.43±0.40). Predictions using Jimenez’s theoretical K cornea – thick gray line in Fig. 3.6– (blue triangles) show a slight increase of asphericity with attempted correction (0.03±0.49). Predictions using the experimental K cornea from the current study –thick black line in Fig. 3– (not shown) estimate significantly higher corneal asphericities (0.78±0.70). It should be noted that throughout the study we have used a rather conservative value for corneal ablation threshold (Fth=40 mJ/cm 2 ). Figure 8 shows predictions with K cornea estimated with a recently reported (Pettit et al., 2005) higher value –Fth=60 mJ/cm 2 – (orange diamonds) which approaches even more (1.39±0.92) the asphericity values found clinically (red diamonds) (1.97±2.00 111
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Doctoral thesis Corneal Ablation an
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Contents Corneal Ablation and Conta
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2.2.1. Fitting surfaces............
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5.3.3. Ablation efficiency factors
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10.5. DISCUSSION...................
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We thank José Antonio Sánchez-Gil
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BOZR Back Optic Zone Radius BCVA Be
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INTRODUCTION 1.1. MOTIVATION The fr
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INTRODUCTION 1.2. THE OPTICAL SYSTE
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INTRODUCTION Myopia is a very commo
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INTRODUCTION a point focus: the dif
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INTRODUCTION system, and tilt repre
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INTRODUCTION term Z 0 2 stands for
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INTRODUCTION which image was shadow
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INTRODUCTION The defocus Zernike te
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INTRODUCTION 1.4.6.3. Internal Aber
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INTRODUCTION 1.5.2.3. Alternating v
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INTRODUCTION and further-more, at l
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INTRODUCTION alcohol is used to loo
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INTRODUCTION changes in reflectivit
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INTRODUCTION Marcos et al. (Marcos
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INTRODUCTION 1.7.3. Ablation effici
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INTRODUCTION corneal surface may be
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INTRODUCTION Algorithm design: The
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INTRODUCTION contact lenses the fie
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INTRODUCTION 1.10.1. Tear studies A
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INTRODUCTION there are still many u
Page 59 and 60: INTRODUCTION 6. Evaluation and unde
Page 61 and 62: METHODS 2Chapter Chapter 2 - Method
Page 63 and 64: METHODS 2.1. MEASUREMENT OF OPTICAL
Page 65 and 66: METHODS In both profilometers, cust
Page 67 and 68: METHODS The measurement method that
Page 69 and 70: METHODS Fig. 2. 9. Set of points in
Page 71 and 72: METHODS Slit lamp Scheimpflug Camer
Page 73 and 74: METHODS representing the deviation
Page 75 and 76: METHODS 2.2.2.2. Ablation pattern f
Page 77 and 78: METHODS direction. These calculatio
Page 79 and 80: METHODS eye through the whole pupil
Page 81 and 82: METHODS (1993) power thresholds for
Page 83 and 84: METHODS alignment (frontal-illumina
Page 85 and 86: METHODS Fig. 2. 24. Example frame f
Page 87 and 88: METHODS 4) New image processing too
Page 89 and 90: METHODS Fig. 2. 28. Corrected entra
Page 91 and 92: METHODS Badal lens, corresponds to
Page 93: METHODS Each VA measurement consist
Page 99: REFRACTIVE SURGERY PMMA MODEL 3.1.
Page 102 and 103: CHAPTER 3 optimization of refractiv
Page 104 and 105: CHAPTER 3 These data demonstrate th
Page 106 and 107: CHAPTER 3 regression line, since it
Page 108 and 109: CHAPTER 3 Figure 3.3 shows one of t
Page 112 and 113: CHAPTER 3 considering the same set
Page 114 and 115: CHAPTER 3 3.5.3 Impact of correctio
Page 117: ABLATION PROPERTIES OF FILOFOCON A
Page 121 and 122: ABLATION PROPERTIES OF FILOFOCON A
Page 133: ABLATION PROPERTIES OF FILOFOCON A
Page 137: OPTIMIZED LASER PLATFORMS 5.1 ABSTR
Page 140 and 141: CHAPTER 5 pulses. Fluence, repetiti
Page 142 and 143: CHAPTER 5 ablations. The slit-confo
Page 144 and 145: CHAPTER 5 (Anera et al., 2003): d S
Page 146 and 147: CHAPTER 5 asymmetries also appeared
Page 148 and 149: CHAPTER 5 5.3.4. Ablation patterns
Page 150 and 151: CHAPTER 5 a) b) : 6.5 mm c) Fig. 5.
Page 152 and 153: CHAPTER 5 achieve proper reflection
Page 154 and 155: CHAPTER 5 Both the ablation algorit
Page 157: HYBRID PORCINE/PLASTIC MODEL 6.1. A
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CHAPTER 6 6.3.1. Hybrid porcine-pla
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CHAPTER 6 is detected. Therefore, i
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CHAPTER 6 no preferential orientati
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ANTERIOR AND POSTERIOR CORNEAL ELEV
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SOFT CONTACT LENS FITTING USING MOD
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SOFT CONTACT LENS FITTING USING MOD
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ON-EYE OPTICAL PERFORMANCE OF RIGID
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SOFT MONOFOCAL AND MULTIFOCAL CONTA
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SOFT MONOFOCAL AND MULTIFOCAL CONTA
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CORRELATION BETWEEN RADIUS AND ASPH
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CONCLUSIONS Conclusions This thesis
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CONCLUSIONS 5We have developed a pr
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CONCLUSIONS LIST OF METHODOLOGICAL
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CONCLUSIONS FUTURE RESEARCH LINES T
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CONCLUSIONS LIST OF PUBLICATIONS AN
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REFERENCES References AIZAWA, D., S
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REFERENCES PHOTODECOMPOSITION (APD)
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REFERENCES DORRONSORO, C., CANO, D.
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REFERENCES GISPETS, J., ARJONA, M.
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REFERENCES KOPF, M., YI, F., ISKAND
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REFERENCES MARCOS, S., DORRONSORO,
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REFERENCES NOVO, A., PAVLOPOULOS, G
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REFERENCES SAKIMOTO, T., ROSENBLATT
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REFERENCES WANG, L., DAI, E., KOCH,
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RESÚMENES pacientes reales fue com
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RESÚMENES experimentales de cirug
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RESÚMENES cada punto de las cornea
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RESÚMENES plástico medidas anteri
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RESÚMENES 8 Evaluación óptica de
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RESÚMENES 9 Prestaciones ópticas
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RESÚMENES 10 Calidad óptica y cal
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RESÚMENES A Correlación entre rad
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CONCLUSIONES clínicos. La descripc
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CONCLUSIONES 12 Las superficies ocu
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CONCLUSIONES IMPLICACIONES DE ESTA
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CONCLUSIONES contribuyen a la compr
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(y muchísimo más difícil). Me da
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