Low_resolution_Thesis_CDD_221009_public - Visual Optics and ...

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

CHAPTER 6 6.3.1. Hybrid porcine-plastic eye model The hybrid porcine/plastic eye models consisted on excised porcine corneas mounted on a 12-mm diameter plastic piston finished on a spherical surface. Figure 6.1 shows a schematic diagram of the model and mount. A strip of sclera was left around the cornea. The corneal samples were fixed on a custom-designed support, using an annular metalic ring that pressed the scleral strip. The piston (hydrated with hyaluronic acid) was slid inside the supporting piece until the corneal button was fit on the spherical surface. Special care was taken to preserve the endothelium integrity. Due to its scattering properties, Pentacam detects the back surface of the cornea and not the underlying plastic support. This mount was designed to avoid bubbles, folds and creases of the corneal tissue, by achieving a smooth corneal back surface conformed to the plastic surface. The amount of stress produced by the piston affected the anterior corneal surface geometry. The enucleated eyes were obtained in a local slaughterhouse, and the procedures were performed within 4 hours post-mortem. Fig. 6.1. Drawing of the Hybrid Porcine/Plastic model. Several plastic surfaces (acrylic material) of known radii of curvature (7.47, 7.93 and 8.75 mm) were used as support for the posterior corneas in this validation study. The plastic surfaces were polished in a precision optics lathe. The radii of curvature of the sphere were measured using a microscope non-contact profilometer (Artigas et al., 2004) (Plμ - Sensofar, Barcelona, Spain) that also reported negligible deviations from the spherical shape. As accurate reconstruction of the posterior corneal surface relies on accurate measurements of the anterior corneal surface and optical and geometrical distortion reconstruction method, a validation of the anterior corneal surface was also performed using high quality optical glass surfaces (optical calipers with nominal radii of 9.65, 8 and 6.15 mm). 6.3.2. Measurements: validation on model eyes The glass spherical surfaces were measured on the Pentacam system (described on section 2.1.3), acting as anterior corneas. Ten measurements were conducted on each surface. One of the plastic spherical surfaces used in the hybrid porcine/plastic eye model (7.93 mm) was also measured directly (acting as anterior surface). Unlike other methods previously tested in our laboratory (as artificial corneas of different RGP materials), the posterior surface of the hybrid porcine/plastic cornea provides images very similar to those obtaines in real eyes (Fig. 6.2). The back surface 160
HYBRID PORCINE/PLASTIC MODEL of the cornea is regular and clearly visible. Therefore, the Pentacam edge detection algorithms work correctly in these images. Besides similar scattering properties, the refraction index in our model cornea is similar to that in the corneas of real eyes, so the geometrical and optical correction algorithms of the Pentacam can be applied. a) b) Patient’s eye Hybrid Porcine/Plastic Fig. 6.2. Scheimpflug images of a human eye and a hybrid porcine/plastic model eye. A total of 12 porcine corneas were used in the validation study (5 porcine corneas were mounted on 7.47-mm and 8.75-mm spherical corneas; and 2 on the 7.93 mm). Each hybrid eye was measured up to 5 times on the Pentacam (with a total of 36 measurements), using identical procedures as in the glass/plastic eyes and patients. The piston pressure was slightly incremented between each two measurements. All the Scheimpflug images (25 per measurement) were carefully supervised to check that the software detected edges of the cornea. Ten measurements (including the whole set of measurements from one porcine cornea) that showed evidences of corneal opacification, edema or bubble formation, either from visual inspection or on the Pentacam, were discarded. Figure 6.3 shows a photograph of the hybrid Porcine/Plastic Model, with an edematized cornea, that produced increased scattering, and prevents Pentacam measurements. Data of anterior and posterior radius of curvature (from the Best Fitting Sphere or Mean horizontal and vertical radii of curvature), asphericity Q (defined as p-1), and astigmatism were obtained from the Pentacam software. Fig. 6.3. Photograph of the hybrid Porcine/Plastic Model. Custom fitting routines in Matlab (Chapter 2 - Methods) could not be used in all the hybrid eyes, as the exporting procedure is interrupted by the software when no iris 161
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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
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
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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
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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
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
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Page 187: 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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