Abstract
We present a fiber-optic dual-confocal laser caliper method for noncontact high-precision sensing and measuring thickness and refractive index of intraocular lens (IOL) implants. The principle of the method is based on sensing and measuring the confocal intensity response of the laser beam reflection from the opposite object surfaces, which provides the advanced feature of having no limitations on the object shape, thickness, and transparency. Using single-mode optical fibers and a 658-nm laser source, the thickness measurement accuracy was assessed to be as high as 5 μm. In addition, refractive index of a transparent object with thickness smaller than the working distance of the focusing lenses can be measured. The thickness and refractive index of a planoconvex IOL were measured with a high accuracy.
Highlights
The development and use of intraocular lens (IOL) implants for refractive cataract surgery have changed the life of cataract patients and have become the most commonly performed surgical procedure since the first IOL implantation demonstrated by Ridley Harold in 1949,1 with an estimated 3 million surgeries per year in the United States[2] and 20 million worldwide.[3]
There have been a number of published reports on the application of optical tools for measurement of thickness,[9,10] refractive index,[11,12] or both[13,14,15,16] of transparent media or biological samples. These tools, impose some specific limitations for testing thickness and refractive index of IOL in terms of spatial sample alignment, testing accuracy, variations of IOL designs, and calibration requirements. Some of these approaches are based on optical interferometry[9,10,12] that will have a limited applicability for testing of both IOL thickness and refractive index due to the complex measurements, the critical spatial alignment requirement of the IOL center to the beam axis, and the availability of IOL designs with different shapes
We present a noncontact method for precise IOL thickness and refractive-index measurement employing an advanced fiber-optic self-calibrating dual-confocal laser caliper approach
Summary
The development and use of intraocular lens (IOL) implants for refractive cataract surgery have changed the life of cataract patients and have become the most commonly performed surgical procedure since the first IOL implantation demonstrated by Ridley Harold in 1949,1 with an estimated 3 million surgeries per year in the United States[2] and 20 million worldwide.[3]. There have been a number of published reports on the application of optical tools for measurement of thickness,[9,10] refractive index,[11,12] or both[13,14,15,16] of transparent media or biological samples These tools, impose some specific limitations for testing thickness and refractive index of IOL in terms of spatial sample alignment, testing accuracy, variations of IOL designs, and calibration requirements. Some of these approaches are based on optical interferometry[9,10,12] that will have a limited applicability for testing of both IOL thickness and refractive index due to the complex measurements, the critical spatial alignment requirement of the IOL center to the beam axis, and the availability of IOL designs with different shapes (convex, concave, etc.). Kim et al.: Noncontact method for sensing thickness and refractive index of intraocular
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