Low_resolution_Thesis_CDD_221009_public - Visual Optics and ...

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CHAPTER 2 +2.50 D, placed right after the collimation lens of the scanner, with its axis perpendicular to the line joining the mirrors of the scanner (axis at 0º), minimized the astigmatism. We then estimated the residual astigmatism by measuring the aberrations of an unaberrated artificial eye. We computed the value of the astigmatism from the 2 2 coefficients Z and 2 Z (oblique and perpendicular astigmatism, respectively) using 2 the equation: 4 Astigmatism( D) 2 2 2 Z 6 Z 2 2 2 6 R pupil (2.3) where R pupil is the radius of the measured pupil. We obtained a value of 0.18±0.03 D (mean and std across 5 measurements). This value (through the corresponding Zernike coefficients) was subtracted from the astigmatism obtained in the measurements. We verified that the sampling pattern selected using the control software was precisely delivered, by projecting the beams on a screen at the pupilary plane and analyzing the images captured by the pupul camera. The mean deviation from the expected position (±standard deviation) across all 37 spot positions was 0.05 (±0.04) mm; 0.08 (±0.05) mm and 0.03 (±0.02) mm for X and Y coordinates, respectively. These differences are smaller than those typically resulting in real eye measurements due to eye movements, and below the variability of the measurement. We checked that these differences do not affect significantly the estimation of aberrations in real eyes (Llorente et al., 2007). Measured defocus Trial lens power Fig. 2. 29. Validation of the defocus compensation. The correct delivery of the samples on the pupil plane is crucial to obtain a reliable measurement. For this reason, a routine to perform quick real time verification of the pattern sampling the pupil plane (“test LRT”) was included in the control software (see Section 2.3.2.4). This routine involves a real-time test of the position of the actual laser spot locations, which must fall within the red circles plotted in the pupillary images (see Fig 2.23), corresponding to the exact sampling locations. Finally, to make sure that the processing program was correct, we confirmed that when computing transverse ray aberrations from the wave aberration (obtained after processing the experimental data), the corresponding spot diagram positions computed matched the spot diagram obtained experimentally. The Badal system included in the set up to compensate for the subject’s ametropic error was also calibrated. Moving the translational stage with two mirrors (Focusing Block) introduces a change in vergence that, for a focal length of 100 mm for each 90
METHODS Badal lens, corresponds to 0.2 D/mm (one dioptre each 5 millimeters). The 0 D position in the focusing block scale was determined using a non aberrated emetropic artificial eye. Trial lenses in front of the artificial eye were used to check the compensation of defocus by the focusing block (Fig. 2. 29). First, we checked by direct observation the change in the spot diagram dispersion when the focusing block was displaced. The final check was performed with the defocus term of the aberration pattern measured. 2.3.2.8. Optical aberrations introduced by the system In order to discard that geometrical aberrations were being introduced by the system, we measured the aberrations of the nominally aberration-free artificial eye. For 3 rd and higher order aberrations we obtained that the RMS departure of the wavefront from the reference sphere was much less than /14 (Marèchal’s criterion (Born and Wolf, 1993)). For 2 nd order aberrations (defocus and astigmatism), the residual values will be subtracted to the measured values. Therefore, we can consider the system is sufficiently corrected for the purposes of measuring human eyes. Absence of chromatic aberration in LRT1 had been verified by measuring the aberrations of a phase plate (Navarro et al., 2000) in front of an artificial eye, using 543 nm and 783 nm as test wavelengths. The difference in defocus obtained with both wavelengths was 0.04D. Similarly, for LRT2 optical aberrations of an artificial eye were measured using infrared wavelength (785nm), under the same conditions (defocus correction, artificial eye position) we used for a wavelength of 532 nm. The difference between the values of defocus for both wavelengths was 0.12 D. 2.3.2.9. Validation of the aberration measurements Measurements of wave aberrations from the systems LRT2 were validated by: 1) measuring cylindrical lenses of known power; 2) measuring phase plates of known aberrations; 3) measurements in plastic artificial eyes of known aberrations (Campbell, 2005), 4) comparing measurements on real eyes also measured with Hartmann-Shack aberrometers. More information can be found in Lourdes Llorente’s (Llorente, 2009) and Elena G. de la Cera’s Thesis (García de la Cera, 2008). 2.3.3. Simulations of retinal images Retinal images were simulated from the results of optical quality (objective) measurements. Simulated retinal visual acuity charts were normally compared to the (subjective) measurements of visual perfomance, described in Section 2.4. Point Spread Functions (PSFs) were obtained from the Zernike polinomial expansions. We performed the 2-dimensional Fourier Transform of the circular pupil function containing the wave aberration function (Atchison and Smith, 2000). In through focus simulations the Zernike defocus coefficient was changed accordingly. The Stiles Crawford function was not considered. From the PSFs we also calculated the Strehl ratio. The retinal images of visual acuity charts were simulated by twodimensional image convolution. 2.4. MEASUREMENT OF VISUAL PERFORMANCE The optical bench described in (Rosales and Marcos, 2006) was used and adapted to perform psychophysical measurements of visual acuity (Fig. 2. 30). The stimuli were presented on high resolution and high brightness minidisplay (LiteEye) through a 91
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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
Page 39 and 40: INTRODUCTION and further-more, at l
Page 41 and 42: INTRODUCTION alcohol is used to loo
Page 43 and 44: INTRODUCTION changes in reflectivit
Page 45 and 46: INTRODUCTION Marcos et al. (Marcos
Page 47 and 48: INTRODUCTION 1.7.3. Ablation effici
Page 49 and 50: INTRODUCTION corneal surface may be
Page 51 and 52: INTRODUCTION Algorithm design: The
Page 53 and 54: INTRODUCTION contact lenses the fie
Page 55 and 56: INTRODUCTION 1.10.1. Tear studies A
Page 57 and 58: 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: METHODS Fig. 2. 28. Corrected entra
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 110 and 111: CHAPTER 3 Ablation efficiency facto
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
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CHAPTER 5 pulses. Fluence, repetiti
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CHAPTER 5 ablations. The slit-confo
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CHAPTER 5 (Anera et al., 2003): d S
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CHAPTER 5 asymmetries also appeared
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CHAPTER 5 5.3.4. Ablation patterns
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CHAPTER 5 a) b) : 6.5 mm c) Fig. 5.
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CHAPTER 5 achieve proper reflection
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CHAPTER 5 Both the ablation algorit
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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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183
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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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