Low_resolution_Thesis_CDD_221009_public - Visual Optics and ...

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

ON-EYE OPTICAL PERFORMANCE OF RIGID GAS PERMEABLE CONTACT LENSES was found. This issue will be discussed in detail in the next subsection. We have checked that the inclusion of the spherical term did not change substantially the correlation values. Subject S1 shows the highest correction (Slope=0.37) and high conformity (R=0.94). Subject S2 shows moderate correction and conformity (Slope=0.92, R=0.76). Subject S3 shows no correction and very high conformity (Slope=1.02, R=0.97) indicating that the lens flexure prevents correction. Subject S4 has good corneal correction and low conformity (Slope=0.53, R=0.65). Fig. 9.6. Correlation between anterior surface Zernike coefficients with and without CL on. Only coefficients up to the 4 th order are included. Spherical aberration was not included. Slopes for each subject’s best linear fit and regression coefficients (R) are also shown. This analysis agrees well with results shown in Fig. 9.4 (a), except for subject S4, for whom there is good corneal correction, but an increase in total RMS. This can be explained by the contribution of internal aberrations. Flexure analysis relates solely to anterior surface aberrations, and for this subject internal aberrations did partially compensate for corneal aberrations. While Fig. 9.6 analyses all Zernike coefficients together, the effect of lens flexure can be studied in each term individually. Optimization of aberration compensation may be achieved by using individual total and corneal aberration data and a careful custom control of lens flexure. Astigmatism is mostly of corneal origin in all subjects but S4. For S1 there is an important decrease in astigmatism (-1.39 D) by RGP CL wear. For S2 and S3 there is only a slight decrease in total astigmatism, as the lens follows the corneal astigmatism almost completely. It is interesting to describe the effects of lens flexure and the different ocular components contribution to astigmatism for subject S4. For S4, internal and corneal astigmatism have values of -0.71 D and -0.47 D but at angles of 142º and 29º. This indicates that corneal and crystalline lens astigmatism have nearly opposite directions (deviation from complete opposition is 23º), so that they are 219
CHAPTER 9 partially compensating each other to produce a final astigmatism of -0.54 at 162º as measured by LRT (or –0.50 at 159º as measured with the autorefractometer). The RGP lens corrects part of the corneal astigmatism, but introduces a slight rotation of 19º (see Fig. 9.2). The deviation from opposition is now 42º, making the compensation less effective. The final astigmatism slightly increases up to -0.61 D. This detailed study can be performed on other higher order aberration terms other than astigmatism. This individual analysis of the effects of lens flexure and the contribution of corneal and internal aberrations in each particular eye suggests that a control of the lens flexure can optimize aberration compensation, depending on the particularities of each eye. In eyes dominated by corneal aberrations (such as S1), high rigidity is advisable. However, for eyes where corneal and internal aberrations are well balanced (among our subjects, S4 is the closest case) a high conformity to the corneal shape would produce best results. All previous analysis has been done for aberrations other than spherical aberration. We did not find that spherical aberration was affected by flexure (Fig. 9.5). Several studies report (Corzine and Klein, 1997) that lens flexure affects the amount of measured regular and irregular astigmatism in astigmatic corneas wearing RGP lens, and this effect depends mostly on lens thickness and to a lesser extent lens material. However, no evidence of flexure has ever been found on spherical corneas suggesting that RGP lenses do not conform to symmetric corneal shapes (Corzine and Klein, 1997). 9.5.3. Tear lens aberrations The spherical aberration of the natural cornea is positive in all eyes with values varying across subjects (Fig. 9.5). The spherical aberration of the anterior surface of the CL shows larger amounts of positive spherical aberration, consistent with spherical lenses, and very similar across subjects. The total spherical aberration is higher than the corneal aberration in one subject (S1), indicating that the crystalline lens adds up to the spherical aberration of the cornea. In the rest of the subjects, we found the previously reported trend that internal negative spherical aberration partially balances the positive corneal spherical aberration, resulting in a low total spherical aberration (Artal and Guirao, 1998). Despite the positive spherical aberration contribution of the RGP CL, as estimated from videokeratographic measurements, we found very low values of total spherical aberration with the RGP CL. Our results suggest that there is a compensation of the positive spherical aberration induced by the CL by the tear lens (i.e. the tear film meniscus between the back surface of the CL and the anterior corneal surface). In the natural eye, the internal aberrations (total minus corneal aberrations) account for the internal ocular optics. In the eye wearing the CL, internal aberrations include the mentioned internal optics and the tear lens. The difference of the internal aberrations from measurements with the CL and the internal aberrations in natural conditions represents the tear lens aberrations. Although this is an indirect and somewhat noisy estimate (0.13 m standard deviation on average, for the spherical aberration coefficient), since it is computed after a double subtraction, we found a common trend in all the tear lens aberration maps from our four subjects. The spherical aberration is typically the largest high order coefficient, and it is always negative (S1:-0.39 m; S2:-0.21 m; S3:-0.14 m; S4:-0.09 m), which explains the described compensation of the lens positive anterior spherical aberrations. 220
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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
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INTRODUCTION 6. Evaluation and unde
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METHODS 2Chapter Chapter 2 - Method
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METHODS 2.1. MEASUREMENT OF OPTICAL
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METHODS In both profilometers, cust
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METHODS The measurement method that
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METHODS Fig. 2. 9. Set of points in
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METHODS Slit lamp Scheimpflug Camer
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METHODS representing the deviation
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METHODS 2.2.2.2. Ablation pattern f
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METHODS direction. These calculatio
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METHODS eye through the whole pupil
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METHODS (1993) power thresholds for
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METHODS alignment (frontal-illumina
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METHODS Fig. 2. 24. Example frame f
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METHODS 4) New image processing too
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METHODS Fig. 2. 28. Corrected entra
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METHODS Badal lens, corresponds to
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METHODS Each VA measurement consist
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REFRACTIVE SURGERY PMMA MODEL 3.1.
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CHAPTER 3 optimization of refractiv
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CHAPTER 3 These data demonstrate th
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CHAPTER 3 regression line, since it
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CHAPTER 3 Figure 3.3 shows one of t
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CHAPTER 3 Ablation efficiency facto
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CHAPTER 3 considering the same set
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CHAPTER 3 3.5.3 Impact of correctio
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ABLATION PROPERTIES OF FILOFOCON A
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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
Page 157: HYBRID PORCINE/PLASTIC MODEL 6.1. A
Page 160 and 161: CHAPTER 6 6.3.1. Hybrid porcine-pla
Page 162 and 163: CHAPTER 6 is detected. Therefore, i
Page 164 and 165: CHAPTER 6 no preferential orientati
Page 167: ANTERIOR AND POSTERIOR CORNEAL ELEV
Page 171 and 172: ANTERIOR AND POSTERIOR CORNEAL ELEV
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Page 187: SOFT CONTACT LENS FITTING USING MOD
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Page 194: ON-EYE OPTICAL PERFORMANCE OF RIGID
Page 198 and 199: ON-EYE OPTICAL PERFORMANCE OF RIGID
Page 212: SOFT MONOFOCAL AND MULTIFOCAL CONTA
Page 216: SOFT MONOFOCAL AND MULTIFOCAL CONTA
Page 220 and 221: CORRELATION BETWEEN RADIUS AND ASPH
Page 230: CONCLUSIONS Conclusions This thesis
Page 233 and 234: CONCLUSIONS 5We have developed a pr
Page 236: CONCLUSIONS LIST OF METHODOLOGICAL
Page 240 and 241: CONCLUSIONS FUTURE RESEARCH LINES T
Page 242 and 243: CONCLUSIONS LIST OF PUBLICATIONS AN
Page 244 and 245: REFERENCES References AIZAWA, D., S
Page 246 and 247: REFERENCES PHOTODECOMPOSITION (APD)
Page 248 and 249: REFERENCES DORRONSORO, C., CANO, D.
Page 250 and 251: REFERENCES GISPETS, J., ARJONA, M.
Page 252 and 253: REFERENCES KOPF, M., YI, F., ISKAND
Page 254 and 255: REFERENCES MARCOS, S., DORRONSORO,
Page 256 and 257: 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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