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 S2 INTERNAL WITH CL INTERNAL WITHOUT CL TEAR LENS Fig. 9.7. Tear lens wave aberration map for S2 (right panel), estimated as the difference of internal aberrations with CL (left panel) and without CL (central panel). A potential compensation by the tear lens of other aberrations, such as astigmatism, has been suggested before (Phillips and Speedwell, 1997). As an example, Fig. 9.7 shows the tear lens wave aberration map for S2 (right panel), estimated as the difference of internal aberrations with CL (left panels) and without CL (central panels). Negative spherical aberration dominates the wave aberration tear lens aberration pattern. We performed a computer simulation to assess potential sources for this additional negative spherical aberration. Using ray tracing, we computed the spherical aberration due only to the tear lens (Ho et al., 2002). We assumed different asphericities for the posterior CL surface (which acted as the anterior surface of the tear lens). We used the actual subjects’ anterior corneal surfaces as the posterior surface of the tear lens. We calculated that for spherical posterior lens surfaces, the tear lens spherical aberration was negative in all cases, following the trend found experimentally. However, the estimated amount (-0.016±0.002 on average) was much lower. The spherical aberration of the tear lens depends on the asphericity of the posterior lens surface. We found that an increase in the asphericity, shifted the spherical aberration of the tear lens toward more negative values (for example the mean spherical aberration for asphericity 0.6 was –0.063±0.004). Nominal asphericities of the posterior surface of the lens are zero (spherical surfaces) for all subjects except for subject S3 (see Table 9.1). However, it is well known that nominal specifications of RGP lenses can vary from actual values, particularly for the posterior surface (Defazio and Lowther, 1979). Deviations from ideal spheres may not be unlikely and a potential cause for the increased (in this case beneficial) negative spherical aberration. 9.6. CONCLUSIONS In this study we have shown the application in real eyes, of combined measurements of aberrometry and corneal topography in RPG CL fitting. By using this methodology, we have been able to evaluate the contribution of the anterior surface of the RGP CL, the internal ocular optics, the flexure and the tear lens aberrations on the optical performance of eyes wearing RGP CL. This information provides an accurate analysis of CL fitting in individual eyes, and allows, for example, to track individual aberration terms through the different optical elements involved (contact lens, tear lens, cornea, internal optics). We have shown that RGP CLs can improve significantly the natural optics of the subject, provided that corneal aberrations are predominant, and the lens flexure is well 221
CHAPTER 9 controlled. Our study concludes that the lens flexure (or conformity) has a great impact on the degree of corneal aberration compensation. As there is previous evidence that internal aberrations usually compensate to some extent the aberrations of the cornea (Artal and Guirao, 1998), we conclude that a custom control on lens flexure can improve the cornea/internal optics aberration ratio and result in an improvement of the subject's visual performance. Finally, we have shown that spherical RGP CLs do not induce higher final spherical aberration on the measured eyes. While the anterior lens surface shows higher spherical aberration than the natural cornea, we found negligible values of total spherical aberration in all our four subjects wearing their RGP CLs. Our results suggest that this compensation is produced by the tear lens, but this could be confirmed on measurements over a larger population, and a strict verification of the parameters of the lens used. 9.7. OUTLOOK We used in real eyes the methodology developed in Chapter 9 for model eyes, and we have confirmed the importance of combined total and corneal measurements to understand contact lens fitting, and to assess critical factors such as the flexure on-eye. We have learned that the internal optics are important when evaluating the fitting of contact lenses on real eyes, and that the tear lens (in between the contact lens and the cornea) affects the optical outcomes in semirigid lenses. With the procedures developed, we can now accomplish the study of more sophisticated contact lens designs on individual eyes. In next Chapter we will use the methodology on real eyes fitted with soft lenses (monofocal and multifocal, as in Chapter 8). In addition, we will conduct measurements of visual outcomes thru-focus, to get an insight of the impact of the optical factors (beyond the contact lens design) on visual performance. 222
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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
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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
Page 258 and 259: 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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