Tunable refractive power by mutual rotation of helical lens parts

2017 ◽  
Author(s):  
Ingo Sieber ◽  
Thomas Martin ◽  
Peter Stiller
Keyword(s):  
Refractive Power ◽  
Mutual Rotation

Corneal refractive power after myopic LASIK

Ophthalmology ◽  
2003 ◽  
Vol 110 (9) ◽  
pp. 1857 ◽  
Author(s):  
Louis E Probst ◽  
Jack T Holladay
Keyword(s):  
Refractive Power ◽  
Corneal Refractive Power

scholarly journals Refractive Power and Biometric Properties of the Nonhuman Primate Isolated Crystalline Lens

2010 ◽  
Vol 51 (4) ◽  
pp. 2118 ◽  
Author(s):  
David Borja ◽  
Fabrice Manns ◽  
Arthur Ho ◽  
Noel M. Ziebarth ◽  
Ana Carolina Acosta ◽  
...  
Keyword(s):  
Nonhuman Primate ◽  
Crystalline Lens ◽  
Refractive Power

scholarly journals Corneal Placido Topography And Its Correlation With The Best Fitting Curve For Non-Astigmatic Eyes

2020 ◽  
Vol 2 (1) ◽  
Author(s):  
Evangelos S. Pateras ◽  
Karaabatsas Konstantinos
Keyword(s):  
Refractive Power ◽  
Best Fitting ◽  
Temporal Side

Placido topographer CSO Phoenix had been used to measure 30 peoples corneas with astigmatism < 0.50 Dc (University of West Attica) and their refractive maps were taken. The refractive power map was used with measurements taken at the horizontal (180°), vertical (90°), and oblique axes (45° and 135°) for each of these 30 people. The keratometric measurements for > 5mm were recorded. The investigation took place at University of West Attica. The results showed that the shape of the cornea varies in the various meridians (e.g. 180° or 90°) and even with oblique meridians (e.g. in the nasal relative to the temporal side) and its curvature correlates with a different equation for each meridian.

scholarly journals Intraocular Lens Power Calculation According to the Difference between Anterior and Total Keratometry Using Scheimpflug Imaging

2021 ◽  
Vol 62 (9) ◽  
pp. 1181-1188
Author(s):  
Joong Hee Kim ◽  
Kyong Jin Cho ◽  
Ho Seok Chung
Keyword(s):  
Regression Analysis ◽  
Absolute Error ◽  
Power Calculation ◽  
Intraocular Lens Power Calculation ◽  
Refractive Power ◽  
Simple Regression Analysis ◽  
The Absolute ◽  
The Difference ◽  
Lens Power ◽  
Simple Regression

Purpose: We investigated the change in the absolute error according to the difference between anterior and total keratometry, to determine the criterion for the difference in keratometry, and to determine the indication for using total keratometry. Methods: Sagittal and total refractive power were measured with 2-, 3-, and 4-mm Pentacam® rings, and the absolute error of each was calculated in patients who underwent cataract surgery in our hospital. The correlation between the difference value the sagittal minus the total refractive power and each absolute error was analyzed by simple regression analysis. The analysis was performed by dividing the patients into two groups based on 0.6, which is the average of the difference between the sagittal and total refractive power for the 3-mm ring. Results: Sagittal power was larger than total refractive power for all rings and the absolute error obtained by applying the total refractive power was larger than the sagittal power for the 2- and 4-mm rings (p < 0.001). The simple regression analysis revealed that the absolute error using sagittal power was positively correlated with the difference between sagittal power and total refractive power. In the group with less than 0.6, the absolute error using the total refractive power of all rings was larger than the sagittal power (p < 0.001). In the group exceeding 0.6, the absolute error using the total refractive power was less than using the sagittal power for the 3 mm ring (p = 0.028). Conclusions: The greater the difference between sagittal and total refractive power, the greater the absolute error using sagittal power. Accuracy was higher in the group exceeding 0.6 after applying total refractive power measured at the 3 mm ring compared to sagittal power.

Hierarchical Features Integration and Attention Iteration Network for Juvenile Refractive Power Prediction

2021 ◽  
pp. 479-490
Author(s):  
Yang Zhang ◽  
Risa Higashita ◽  
Guodong Long ◽  
Rong Li ◽  
Daisuke Santo ◽  
...  
Keyword(s):  
Power Prediction ◽  
Refractive Power ◽  
Hierarchical Features

scholarly journals Simulation of an Adaptive Fluid-Membrane Piezoelectric Lens

Micromachines ◽  
2019 ◽  
Vol 10 (12) ◽  
pp. 797
Author(s):  
Hitesh Gowda Bettaswamy Bettaswamy Gowda ◽  
Ulrike Wallrabe
Keyword(s):  
Thermal Expansion ◽  
Simulation Model ◽  
Fluid Pressure ◽  
Flexible Membrane ◽  
Membrane Deformation ◽  
Fluid Forces ◽  
Refractive Power ◽  
Element Simulation ◽  
Fluid Membrane ◽  
Internal Fluid

In this paper, we present a finite-element simulation of an adaptive piezoelectric fluid-membrane lens for which we modelled the fluid-structure interaction and resulting membrane deformation in COMSOL Multiphysics®. Our model shows the explicit coupling of the piezoelectric physics with the fluid dynamics physics to simulate the interaction between the piezoelectric and the fluid forces that contribute to the deformation of a flexible membrane in the adaptive lens. Furthermore, the simulation model is extended to describe the membrane deformation by additional fluid forces from the fluid thermal expansion. Subsequently, the simulation model is used to study the refractive power of the adaptive lens as a function of internal fluid pressure and analyze the effect of the fluid thermal expansion on the refractive power. Finally, the simulation results of the refractive power are compared to the experimental results at different actuation levels and temperatures validating the coupled COMSOL model very well. This is explicitly proven by explaining an observed positive drift of the refractive power at higher temperatures.

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