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Hong Y, Liu D, Zou H, Jia Q, Tang S, Lin Q. Refractive index adjustable intraocular lens design to achieve diopter control for improving the treatment of ametropia after cataract surgery. Acta Biomater 2024; 178:124-136. [PMID: 38423352 DOI: 10.1016/j.actbio.2024.02.033] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2024] [Revised: 02/17/2024] [Accepted: 02/20/2024] [Indexed: 03/02/2024]
Abstract
Intraocular lens (IOL) implantation is currently the most effective clinical treatment for cataracts. Nevertheless, due to the growth of the eye axis in patients with congenital cataracts during the process of growth and development, the progressive incapacity of an IOL with a fixed focus does not meet the demands of practical usage, leading to the occurrence of ametropia. This work describes an innovative class of an IOL bulk material that offers good biosafety and light-controlled refractive index adjustment. Acrylate materials were synthesized for the preparation of IOLs by free radical polymerization of ethylene glycol phenyl ether methacrylate (EGPEMA), hydrophilic monomer 2-(2-ethoxyethoxy) ethyl acrylate (EA), and functional monomer hydroxymethyl coumarin methacrylate (CMA). Under 365/254 nm ultraviolet (UV) irradiation, the coumarin group could adjust the polymer material's refractive index through reversible photoinduced dimerization/depolymerization. Meanwhile, the potential for the IOL use is enabled by its satisfactory biosafety. Such a light-induced diopter adjustable IOL will be more appropriate for implantation during cataract surgery since it will not require the correction needed for ametropia and will offer more accurate and humane treatment. STATEMENT OF SIGNIFICANCE.
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Affiliation(s)
- Yueze Hong
- National Engineering Research Center of Ophthalmology and Optometry, School of Biomedical Engineering, School of Ophthalmology and Optometry, Eye Hospital, Wenzhou Medical University, Wenzhou 325027, China
| | - Dong Liu
- National Engineering Research Center of Ophthalmology and Optometry, School of Biomedical Engineering, School of Ophthalmology and Optometry, Eye Hospital, Wenzhou Medical University, Wenzhou 325027, China
| | - Haoyu Zou
- National Engineering Research Center of Ophthalmology and Optometry, School of Biomedical Engineering, School of Ophthalmology and Optometry, Eye Hospital, Wenzhou Medical University, Wenzhou 325027, China
| | - Qingqing Jia
- National Engineering Research Center of Ophthalmology and Optometry, School of Biomedical Engineering, School of Ophthalmology and Optometry, Eye Hospital, Wenzhou Medical University, Wenzhou 325027, China
| | - Sihan Tang
- National Engineering Research Center of Ophthalmology and Optometry, School of Biomedical Engineering, School of Ophthalmology and Optometry, Eye Hospital, Wenzhou Medical University, Wenzhou 325027, China
| | - Quankui Lin
- National Engineering Research Center of Ophthalmology and Optometry, School of Biomedical Engineering, School of Ophthalmology and Optometry, Eye Hospital, Wenzhou Medical University, Wenzhou 325027, China.
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Huang R, Yu D, Savage D, Wozniak K, Zheleznyak L, Knox WH, Huxlin KR. Blue-LIRIC in the rabbit cornea: efficacy, tissue effects, and repetition rate scaling. BIOMEDICAL OPTICS EXPRESS 2022; 13:2346-2363. [PMID: 35519279 PMCID: PMC9045900 DOI: 10.1364/boe.448286] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/10/2021] [Revised: 01/20/2022] [Accepted: 03/10/2022] [Indexed: 06/14/2023]
Abstract
Laser-induced refractive index change (LIRIC) is being developed as a non-invasive way to alter optical properties of transparent, ophthalmic materials including corneas ex vivo and in vivo. This study examined the optical and biological effects of blue-LIRIC (wavelengths 400-405 nm) of ex-vivo rabbit corneas. Following LIRIC treatment at low and high repetition rates (8.3 MHz and 80 MHz, respectively), we interferometrically measured optical phase change, obtained transmission electron microscopy (TEM) micrographs, and stained histological sections with collagen hybridizing peptides (CHP) to assess the structural and organizational changes caused by LIRIC at different repetition rates. Finally, we performed power and scan speed scaling experiments at three different repetition rates (1 MHz, 8.3 MHz, and 80 MHz) to study their impact on LIRIC efficacy. Histologic co-localization of CHP and LIRIC-generated green autofluorescence signals suggested that collagen denaturation had occurred in the laser-irradiated region. TEM imaging showed different ultrastructural modifications for low and high repetition rate writing, with discrete homogenization of collagen fibrils at 80 MHz, as opposed to contiguous homogenization at 8.3 MHz. Overall, this study confirmed that LIRIC efficacy can be dramatically increased, while still avoiding tissue ablation, by lowering the repetition rate from 80 MHz to 8.3 MHz. Modeling suggests that this is due to a higher, single-pulse, energy density deposition at given laser powers during 8.3 MHz LIRIC.
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Affiliation(s)
- Ruiting Huang
- The Institute of Optics, University of Rochester, Rochester, NY 14627, USA
| | - Dan Yu
- Materials Science Program, University of Rochester, Rochester, NY 14627, USA
| | - Daniel Savage
- The Institute of Optics, University of Rochester, Rochester, NY 14627, USA
- Flaum Eye Institute, University of Rochester, Rochester, NY 14627, USA
| | - Kaitlin Wozniak
- The Institute of Optics, University of Rochester, Rochester, NY 14627, USA
- Flaum Eye Institute, University of Rochester, Rochester, NY 14627, USA
| | | | - Wayne H. Knox
- The Institute of Optics, University of Rochester, Rochester, NY 14627, USA
- Materials Science Program, University of Rochester, Rochester, NY 14627, USA
- Center for Visual Science, University of Rochester, Rochester, NY 14627, USA
| | - Krystel R. Huxlin
- The Institute of Optics, University of Rochester, Rochester, NY 14627, USA
- Flaum Eye Institute, University of Rochester, Rochester, NY 14627, USA
- Center for Visual Science, University of Rochester, Rochester, NY 14627, USA
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Wu Y, Xu J, Ding P, Knox WH. Modification of surface morphology of hydrogels due to subsurface femtosecond laser micromachining. APPLIED OPTICS 2021; 60:9799-9808. [PMID: 34807167 DOI: 10.1364/ao.438297] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/22/2021] [Accepted: 10/04/2021] [Indexed: 06/13/2023]
Abstract
In this paper, we studied the effects of subsurface femtosecond laser micromachining on surface morphology in hydrogels. Depending on material properties and writing conditions, we found surface bumps when materials were hydrated, and trenches when they were dehydrated, which can be attributed to the localized change in water concentration. Such wavy surfaces by laser-induced refractive index change are not desirable in clinical contact lenses. Therefore, the minimization of surface bumps is necessary to ensure the user eye wearing comfort. In addition, we examined the optical effects of the surface features using interferometry and the surface morphology using profilometry. Finally, we proposed a simplified mechanical model based on localized swelling.
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Chang DH, Waring GO, Hom M, Barnett M. Presbyopia Treatments by Mechanism of Action: A New Classification System Based on a Review of the Literature. Clin Ophthalmol 2021; 15:3733-3745. [PMID: 34522079 PMCID: PMC8432361 DOI: 10.2147/opth.s318065] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2021] [Accepted: 07/08/2021] [Indexed: 01/07/2023] Open
Abstract
Presbyopia, a loss of accommodative ability associated with aging, is a significant cause of vision impairment globally. At the clinical level, it is a frustrating and difficult issue that negatively impacts patients’ quality of life. Less appreciated is the fact that loss of accommodative ability and its current treatments methods may present safety concerns, for example, increasing the risk of falls. Therefore, a more complete understanding of treatment options with respect to how they relate to the natural ability of the eye is needed to improve decision making and to aid clinicians in individualizing treatment options. This article reviews the options for expanding functional through focus—a term coined to describe the ability of the eye to see at all distances with minimal latency—by how they vary the refractive power over time, across the visual field, between eyes, or across a range of distances. ![]()
Point your SmartPhone at the code above. If you have a QR code reader the video abstract will appear. Or use: https://youtu.be/HZw7qvIu6pw
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Affiliation(s)
| | | | | | - Melissa Barnett
- University of California, Davis Eye Center, Sacramento, CA, USA
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5
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Wu Y, Knox W. Directional phase-unwrapping algorithm and phase shift technique on hydrogel. APPLIED OPTICS 2021; 60:3901-3908. [PMID: 33983328 DOI: 10.1364/ao.420397] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/22/2021] [Accepted: 04/01/2021] [Indexed: 06/12/2023]
Abstract
Refractive index microstructures, which can be written by multiphoton absorption with femtosecond lasers, have many applications. Here we present a directional phase-unwrapping algorithm with phase-shifting technique and apply it to the metrology of hydrogel microstructures. A staircase phase-unwrapping algorithm is demonstrated. This fast quality-guided path phase-unwrapping applies well to situations that are geometrically well defined and is quite tolerant of phase noise. To achieve precise very small phase shifts, we also present a slant angle technique on a DC servo stage along with phase shift measurement, allowing us to achieve 6.5 nm step sizes.
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Ang M, Gatinel D, Reinstein DZ, Mertens E, Alió Del Barrio JL, Alió JL. Refractive surgery beyond 2020. Eye (Lond) 2020; 35:362-382. [PMID: 32709958 DOI: 10.1038/s41433-020-1096-5] [Citation(s) in RCA: 64] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2020] [Revised: 05/19/2020] [Accepted: 07/08/2020] [Indexed: 02/07/2023] Open
Abstract
Refractive surgery refers to any procedure that corrects or minimizes refractive errors. Today, refractive surgery has evolved beyond the traditional laser refractive surgery, embodied by the popular laser in situ keratomileusis or 'LASIK'. New keratorefractive techniques such as small incision lenticule extraction (SMILE) avoids corneal flap creation and uses a single laser device, while advances in surface ablation techniques have seen a resurgence in its popularity. Presbyopic treatment options have also expanded to include new ablation profiles, intracorneal implants, and phakic intraocular implants. With the improved safety and efficacy of refractive lens exchange, a wider variety of intraocular lens implants with advanced optics provide more options for refractive correction in carefully selected patients. In this review, we also discuss possible developments in refractive surgery beyond 2020, such as preoperative evaluation of refractive patients using machine learning and artificial intelligence, potential use of stromal lenticules harvested from SMILE for presbyopic treatments, and various advances in intraocular lens implants that may provide a closer to 'physiological correction' of refractive errors.
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Affiliation(s)
- Marcus Ang
- Singapore Eye Research Institute, Singapore National Eye Centre, Singapore, Singapore. .,Department of Ophthalmology and Visual Science, Duke-NUS Graduate Medical School, Singapore, Singapore.
| | | | - Dan Z Reinstein
- London Vision Clinic, London, UK.,Department of Ophthalmology, Columbia University Medical Center, New York, NY, USA.,Sorbonne Université, Paris, France.,Biomedical Science Research Institute, Ulster University, Belfast, UK
| | - Erik Mertens
- Medipolis-Antwerp Private Clinic, Antwerp, Belgium
| | - Jorge L Alió Del Barrio
- Division of Ophthalmology, School of Medicine, Universidad Miguel Hernández, Alicante, Spain.,Cornea, Cataract and Refractive Surgery Unit, Vissum (Miranza Group), Alicante, Spain
| | - Jorge L Alió
- Division of Ophthalmology, School of Medicine, Universidad Miguel Hernández, Alicante, Spain.,Cornea, Cataract and Refractive Surgery Unit, Vissum (Miranza Group), Alicante, Spain
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Campaign SMG, Knox WH. Increase in efficacy of near-infrared femtosecond micromachining in ophthalmic hydrogels with the addition of sodium fluorescein, rose bengal, and riboflavin. APPLIED OPTICS 2019; 58:8959-8970. [PMID: 31873678 DOI: 10.1364/ao.58.008959] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/16/2019] [Accepted: 10/14/2019] [Indexed: 06/10/2023]
Abstract
We report on the effect of exogenous doping agents with large two-photon absorption cross sections on the efficacy of near-infrared femtosecond micromachining in ophthalmic hydrogels. Contaflex GM Advance 58 hydrogels were solution doped in low concentrations of sodium fluorescein, rose bengal, and riboflavin dissolved in balanced salt solution prior to femtosecond micromachining with three near-infrared wavelengths: 720, 800, and 1035 nm. Using any of the three doping agents in the concentrations studied produced an increase in the amount of optical phase change induced in the material at all writing wavelengths and reduced the amount of power needed to induce a desired amount of phase change.
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Patel S, Tutchenko L. The refractive index of the human cornea: A review. Cont Lens Anterior Eye 2019; 42:575-580. [PMID: 31064697 DOI: 10.1016/j.clae.2019.04.018] [Citation(s) in RCA: 42] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2018] [Revised: 04/14/2019] [Accepted: 04/30/2019] [Indexed: 10/26/2022]
Abstract
The refractive index of the cornea and overlying tear film are key factors affecting refraction and overall optical properties of the eye. A figure of 1.376 is often quoted for the refractive index of the human cornea over the visible spectrum. In the 19th century estimates for the average refractive index of the human cornea ranged from 1.335 to 1.4391. Over the last two decades data obtained from either ex or in vivo corneas (under local anaesthesia with or without stromal resection) by contact Abbé refractometry show the refractive index of the cornea changes along its' depth undulating from around 1.400 at the epithelium to 1.380 at Bowman's layer, a low of 1.369 in the mid stroma and 1.373 at the endothelium. The mean refractive index of harvested tear samples is 1.337 rising to 1.482 for the overlying lipid layer. Contemporary measurements obtained in vivo by non-invasive methods reveal the average, or equivalent, refractive index of the tear film-cornea complex along the antero-posterior direction ranges from 1.423 to 1.436. Over the last 200 years calculations, with respect to the optics of the human eye, were based on values for the refractive index of the cornea obtained from invasive techniques. The refractive index of the cornea and overlying tear film appears to be higher than previously accepted and varies from case to case.
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Affiliation(s)
- Sudi Patel
- NHS National Services Scotland, Edinburgh, United Kingdom.
| | - Larysa Tutchenko
- Department of Ophthalmology, Shupyk National Medical Academy of Postgraduate Education, Kyiv, Ukraine; Kyiv City Clinical Ophthalmological Hospital "Eye Microsurgical Center", Kyiv, Ukraine
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Lam B, Guo C. Complete characterization of ultrashort optical pulses with a phase-shifting wedged reversal shearing interferometer. LIGHT, SCIENCE & APPLICATIONS 2018; 7:30. [PMID: 30839594 PMCID: PMC6106999 DOI: 10.1038/s41377-018-0022-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/14/2017] [Revised: 04/17/2018] [Accepted: 04/22/2018] [Indexed: 06/09/2023]
Abstract
The ability of an interferometer to characterize the spatial information of a light beam is often limited by the temporal profile of the beam, with femtosecond pulse characterization being particularly challenging. In this study, we developed a simple, stable, controllable shearing and vectorial phase-shifting wedged reversal shearing interferometer that is able to characterize all types of coherent and partially coherent light beams. The proposed interferometer consists of only a single beam splitter cube with one wedged entrance face and is insensitive to environmental vibration due to its common path configuration. A near zero-path length difference of the proposed interferometer ensures its operation for ultrashort pulses, providing, for the first time, a simple and stable interferometric tool to fully characterize sub-100 fs laser pulses. All common beam characterization can be carried out with the interferometer, such as the amplitude, phase, polarization, wavelength, and pulse duration. Furthermore, this technique is sensitive to the wavefront tilt and can be used for precise beam alignment. Therefore, this interferometer can be an essential tool for beam characterization, optical imaging, and the testing required for a wide range of applications, including astronomy, biomedicine, ophthalmology, optical testing and imaging systems, and adaptive optics.
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Affiliation(s)
- Billy Lam
- The Institute of Optics, University of Rochester, Rochester, NY 14627 USA
- Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, 130033 Changchun, China
| | - Chunlei Guo
- The Institute of Optics, University of Rochester, Rochester, NY 14627 USA
- Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, 130033 Changchun, China
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Abstract
Ophthalmology was the first medical specialty to adopt lasers right after their invention more than 50 years ago, and they gradually revolutionized ocular imaging, diagnostics, therapy, and surgery. Challenging precision, safety, and selectivity requirements for ocular therapeutic and surgical procedures keep advancing the laser technologies, which in turn continue enabling novel applications for the preservation and restoration of sight. Modern lasers can provide single-cell-layer selectivity in therapy, submicrometer precision in three-dimensional image-guided surgery, and nondamaging retinal therapy under optoacoustic temperature control. This article reviews the evolution of laser technologies; progress in understanding of the laser-tissue interactions; and concepts, misconceptions, and accidental discoveries that led to modern therapeutic and surgical applications of lasers in ophthalmology. It begins with a brief historical overview, followed by a description of the laser-tissue interactions and corresponding ophthalmic applications.
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Affiliation(s)
- Daniel Palanker
- Department of Ophthalmology and Hansen Experimental Physics Laboratory, Stanford University, Stanford, California 94305;
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Wozniak KT, Elkins N, Brooks DR, Savage DE, MacRae S, Ellis JD, Knox WH, Huxlin KR. Contrasting cellular damage after Blue-IRIS and Femto-LASIK in cat cornea. Exp Eye Res 2017; 165:20-28. [PMID: 28866013 DOI: 10.1016/j.exer.2017.08.018] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2017] [Revised: 08/17/2017] [Accepted: 08/28/2017] [Indexed: 11/25/2022]
Abstract
Blue-intra-tissue refractive index shaping (Blue-IRIS) is a new approach to laser refractive correction of optical aberrations in the eye, which alters the refractive index of the cornea rather than changing its shape. Before it can be implemented in humans, it is critical to establish whether and to what extent, Blue-IRIS damages the cornea. Here, we contrasted the impact of -1.5 D cylinder refractive corrections inscribed using either Blue-IRIS or femtosecond laser in-situ keratomileusis (femto-LASIK) on corneal cell viability. Blue-IRIS was used to write a -1.5 D cylinder gradient index (GRIN) lens over a 2.5 mm by 2.5 mm area into the mid-stromal region of the cornea in six freshly-enucleated feline eyes. The same correction (-1.5 D cylinder) was inscribed into another four cat eyes using femto-LASIK. Six hours later, all corneas were processed for histology and stained for terminal deoxynucleotidyl transferase-mediated dUTP-digoxigenin nick end labeling (TUNEL) and p-γ-H2AX to label damaged cells. In Blue-IRIS-treated corneas, no tissue was removed and TUNEL-stained cells were confined to the laser focal zone in the stroma. In femto-LASIK, photoablation removed 14 μm of anterior stroma, but in addition, TUNEL-positive cells clustered across the femto-flap, the epithelium at the flap edges and the stroma below the ablation zone. Keratocytes positive for p-γ-H2AX were seen adjacent to all Blue-IRIS focal zones, but were completely absent from femto-LASIK-treated corneas. Unlike femto-LASIK, Blue-IRIS attains refractive correction in the cornea without tissue removal and only causes minimal, localized keratocyte death within the laser focal zones. In addition, Blue-IRIS induced DNA modifications associated with phosphorylation of γ-H2AX in keratocytes adjacent to the laser focal zones. We posit that this p-γ-H2AX response is related to alterations in chromatin structure caused by localized changes in osmolarity, a possible mechanism for the induced refractive index changes.
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Affiliation(s)
- Kaitlin T Wozniak
- The Institute of Optics, University of Rochester, Rochester, NY 14627, USA
| | - Noah Elkins
- Department of Biomedical Engineering, University of Rochester, Rochester, NY 14627, USA
| | - Daniel R Brooks
- The Institute of Optics, University of Rochester, Rochester, NY 14627, USA
| | - Daniel E Savage
- The Institute of Optics, University of Rochester, Rochester, NY 14627, USA; Center for Visual Science, University of Rochester, Rochester, NY 14627, USA; Flaum Eye Institute, University of Rochester, Rochester, NY 14627, USA
| | - Scott MacRae
- Center for Visual Science, University of Rochester, Rochester, NY 14627, USA; Flaum Eye Institute, University of Rochester, Rochester, NY 14627, USA
| | - Jonathan D Ellis
- The Institute of Optics, University of Rochester, Rochester, NY 14627, USA; Department of Mechanical Engineering, University of Rochester, Rochester, NY 14627, USA
| | - Wayne H Knox
- The Institute of Optics, University of Rochester, Rochester, NY 14627, USA; Center for Visual Science, University of Rochester, Rochester, NY 14627, USA
| | - Krystel R Huxlin
- Center for Visual Science, University of Rochester, Rochester, NY 14627, USA; Flaum Eye Institute, University of Rochester, Rochester, NY 14627, USA.
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Wozniak KT, Gearhart SM, Savage DE, Ellis JD, Knox WH, Huxlin KR. Comparable change in stromal refractive index of cat and human corneas following blue-IRIS. JOURNAL OF BIOMEDICAL OPTICS 2017; 22:55007. [PMID: 28538957 PMCID: PMC5443415 DOI: 10.1117/1.jbo.22.5.055007] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/13/2016] [Accepted: 05/08/2017] [Indexed: 06/07/2023]
Abstract
Blue intratissue refractive index shaping (blue-IRIS) is a method with potential to correct ocular refraction noninvasively in humans. To date, blue-IRIS has only ever been applied to cat corneas and hydrogels. To test the comparability of refractive index change achievable in cat and human tissues, we used blue-IRIS to write identical phase gratings in ex vivo feline and human corneas. Femtosecond pulses (400 nm) were focused ? 300 ?? ? m below the epithelial surface of excised cat and human corneas and scanned to write phase gratings with lines ? 1 ?? ? m wide, spaced 5 ?? ? m apart, using a scan speed of 5 ?? mm / s . Additional cat corneas were used to test writing at 3 and 7 ?? mm / s in order to document speed dependence of the refractive index change magnitude. The first-order diffraction efficiency was immediately measured and used to calculate the refractive index change attained. Our data show that blue-IRIS induces comparable refractive index changes in feline and human corneas, an essential requirement for further developing its use as a clinical vision correction technique.
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Affiliation(s)
- Kaitlin T. Wozniak
- University of Rochester, Institute of Optics, Rochester, New York, United States
| | - Sara M. Gearhart
- University of Rochester, Institute of Optics, Rochester, New York, United States
| | - Daniel E. Savage
- University of Rochester, Institute of Optics, Rochester, New York, United States
- University of Rochester, Center for Visual Science, Rochester, New York, United States
- University of Rochester, Flaum Eye Institute, Rochester, New York, United States
| | - Jonathan D. Ellis
- University of Rochester, Institute of Optics, Rochester, New York, United States
- University of Rochester, Department of Mechanical Engineering, Rochester, New York, United States
| | - Wayne H. Knox
- University of Rochester, Institute of Optics, Rochester, New York, United States
- University of Rochester, Center for Visual Science, Rochester, New York, United States
- University of Rochester, Flaum Eye Institute, Rochester, New York, United States
| | - Krystel R. Huxlin
- University of Rochester, Center for Visual Science, Rochester, New York, United States
- University of Rochester, Flaum Eye Institute, Rochester, New York, United States
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Jin L, Jiang F, Dai N, Peng J, Hu M, He S, Fang K, Yang X. Sclerectomy with nanojoule energy level per pulse by femtosecond fiber laser in vitro. OPTICS EXPRESS 2015; 23:22012-22023. [PMID: 26368176 DOI: 10.1364/oe.23.022012] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
The use of nanojoule femtosecond pulses (NFP) for highly precise proceeding in anti-glaucoma surgery was evaluated. According to the observation of scanning electron microscopy (SEM), four types of incision patterns, including subsurface, slit-like, spot and cuboid ablations, were accomplished on in vitro sclera by NFP with little collateral damage. In comparison to microjoule femtosecond pulses (MFP), NFP can make extremely precise incisions with smoother inner surface with less peak power density. The present study first illustrates the potential use of NFP in minimally invasive laser sclerectomy for glaucoma therapy.
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Wang J, Schuele G, Palanker D. Finesse of transparent tissue cutting by ultrafast lasers at various wavelengths. JOURNAL OF BIOMEDICAL OPTICS 2015; 20:125004. [PMID: 26720869 DOI: 10.1117/1.jbo.20.12.125004] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/09/2015] [Accepted: 11/19/2015] [Indexed: 05/05/2023]
Abstract
Transparent ocular tissues, such as the cornea and crystalline lens, can be ablated or dissected using short-pulse lasers. In refractive and cataract surgeries, the cornea, lens, and lens capsule can be cut by producing dielectric breakdown in the focus of a near-infrared (IR) femtosecond laser, which results in explosive vaporization of the interstitial water, causing mechanical rupture of the surrounding tissue. Here, we compare the texture of edges of lens capsule cut by femtosecond lasers with IR and ultraviolet (UV) wavelengths and explore differences in interactions of these lasers with biological molecules. Scanning electron microscopy indicates that a 400-nm laser is capable of producing very smooth cut edges compared to 800 or 1030 nm at a similar focusing angle. Using gel electrophoresis and liquid chromatography/mass spectrometry, we observe laser-induced nonlinear breakdown of proteins and polypeptides by 400-nm femtosecond pulses above and below the dielectric breakdown threshold. On the other hand, 800-nm femtosecond lasers do not produce significant dissociation even above the threshold of dielectric breakdown. However, despite this additional interaction of UV femtosecond laser with proteins, we determine that efficient cutting requires plasma-mediated bubble formation and that remarkably smooth edges are the result of reduced thresholds and smaller focal volume.
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Affiliation(s)
- Jenny Wang
- Stanford University, Department of Applied Physics, 452 Lomita Mall, Stanford, California 94305, United States
| | - Georg Schuele
- Abbott Medical Optics, 1310 Moffett Park Drive, Sunnyvale, California 94089, United States
| | - Daniel Palanker
- Stanford University, Department of Ophthalmology, 452 Lomita Mall, Stanford, California 94305, United StatesdStanford University, Hansen Experimental Physics Laboratory, 452 Lomita Mall, Stanford, California 94305, United States
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15
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Savage DE, Brooks DR, DeMagistris M, Xu L, MacRae S, Ellis JD, Knox WH, Huxlin KR. First demonstration of ocular refractive change using blue-IRIS in live cats. Invest Ophthalmol Vis Sci 2014; 55:4603-12. [PMID: 24985471 DOI: 10.1167/iovs.14-14373] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
PURPOSE To determine the efficacy of intratissue refractive index shaping (IRIS) using 400-nm femtosecond laser pulses (blue light) for writing refractive structures directly into live cat corneas in vivo, and to assess the longevity of these structures in the eyes of living cats. METHODS Four eyes from two adult cats underwent Blue-IRIS. Light at 400 nm with 100-femtosecond (fs) pulses were tightly focused into the corneal stroma of each eye at an 80-MHz repetition rate. These pulses locally increased the refractive index of the corneal stroma via an endogenous, two-photon absorption process and were used to inscribe three-layered, gradient index patterns into the cat corneas. The optical effects of the patterns were then tracked using optical coherence tomography (OCT) and Shack-Hartmann wavefront sensing. RESULTS Blue-IRIS patterns locally changed ocular cylinder by -1.4 ± 0.3 diopters (D), defocus by -2.0 ± 0.5 D, and higher-order root mean square (HORMS) by 0.31 ± 0.04 μm at 1 month post-IRIS, without significant changes in corneal thickness or curvature. Refractive changes were maintained for the duration they were tracked, 12 months post-IRIS in one eye, and just more than 3 months in the remaining three eyes. CONCLUSIONS Blue-IRIS can be used to inscribe refractive structures into live cat cornea in vivo that are stable for at least 12 months, and are not associated with significant alterations in corneal thicknesses or radii of curvature. This result is a critical step toward establishing Blue-IRIS as a promising technique for noninvasive vision correction.
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Affiliation(s)
- Daniel E Savage
- The Institute of Optics, University of Rochester, Rochester, New York, United States Center for Visual Science, University of Rochester, Rochester, New York, United States
| | - Daniel R Brooks
- The Institute of Optics, University of Rochester, Rochester, New York, United States
| | - Margaret DeMagistris
- Flaum Eye Institute, University of Rochester, Rochester, New York, United States
| | - Lisen Xu
- The Institute of Optics, University of Rochester, Rochester, New York, United States
| | - Scott MacRae
- Center for Visual Science, University of Rochester, Rochester, New York, United States Flaum Eye Institute, University of Rochester, Rochester, New York, United States
| | - Jonathan D Ellis
- The Institute of Optics, University of Rochester, Rochester, New York, United States Department of Mechanical Engineering, University of Rochester, Rochester, New York, United States
| | - Wayne H Knox
- The Institute of Optics, University of Rochester, Rochester, New York, United States Center for Visual Science, University of Rochester, Rochester, New York, United States
| | - Krystel R Huxlin
- Center for Visual Science, University of Rochester, Rochester, New York, United States Flaum Eye Institute, University of Rochester, Rochester, New York, United States
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16
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Brooks DR, Brown NS, Savage DE, Wang C, Knox WH, Ellis JD. Precision large field scanning system for high numerical aperture lenses and application to femtosecond micromachining of ophthalmic materials. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2014; 85:065107. [PMID: 24985852 DOI: 10.1063/1.4880727] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
A precision, large stroke (nearly 1 cm) scanning system was designed, built, and calibrated for micromachining of ophthalmic materials including hydrogels and cornea (excised and in vivo). This system comprises a flexure stage with an attached objective on stacked vertical and horizontal translation stages. This paper outlines the design process leading to our most current version including the specifications that were used in the design and the drawbacks of other methods that were previously used. Initial measurements of the current version are also given. The current flexure was measured to have a 27 Hz natural frequency with no load.
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Affiliation(s)
- D R Brooks
- The Institute of Optics, University of Rochester, Rochester, New York 14627, USA
| | - N S Brown
- The Institute of Optics, University of Rochester, Rochester, New York 14627, USA
| | - D E Savage
- The Institute of Optics, University of Rochester, Rochester, New York 14627, USA
| | - C Wang
- Department of Electrical and Computer Engineering, University of Rochester, Rochester, New York 14627, USA
| | - W H Knox
- The Institute of Optics, University of Rochester, Rochester, New York 14627, USA
| | - J D Ellis
- The Institute of Optics, University of Rochester, Rochester, New York 14627, USA
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Sidhu MS, Choi MY, Woo SY, Lee HK, Lee HS, Kim KJ, Jeoung SC, Choi JS, Joo CK, Park IH. Femtosecond laser-assisted selective reduction of neovascularization in rat cornea. Lasers Med Sci 2014; 29:1417-27. [PMID: 24570086 PMCID: PMC4074465 DOI: 10.1007/s10103-014-1545-0] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2013] [Accepted: 02/04/2014] [Indexed: 11/30/2022]
Abstract
Nonlinear multiphoton absorption induced by focusing near infrared (NIR) femtosecond (fs) laser pulses into a transparent cornea allows surgery on neovascular structures with minimal collateral damage. In this report, we introduce an fs laser-based microsurgery for selective treatment of rat corneal neovascularizations (in vivo). Contiguous tissue effects are achieved by scanning a focused laser pulse below the corneal surface with a fluence range of 2.2–8.6 J/cm2. The minimal visible laser lesion (MVL) threshold determined over the corneal neovascular structures was found to be 4.3 J/cm2. Histological and optical coherence tomography examinations of the anterior segment after laser irradiations show localized degeneration of neovascular structures without any unexpected change in adjacent tissues. Furthermore, an approximately 30 % reduction in corneal neovascularizations was observed after 5 days of fs laser exposure. The femtosecond laser is thus a promising tool for minimally invasive intrastromal surgery with the aid of a significantly smaller and more deterministic photodisruptive energy threshold for the interaction between the fs laser pulse and corneal neovascular structures.
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Affiliation(s)
- Mehra S Sidhu
- Center for Medical Metrology, Division of Convergence Technology, Korea Research Institute of Standards and Science, Daejeon, 305 340, Republic of Korea
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18
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Ackermann R, Kammel R, Merker M, Kamm A, Tünnermann A, Nolte S. Optical side-effects of fs-laser treatment in refractive surgery investigated by means of a model eye. BIOMEDICAL OPTICS EXPRESS 2013; 4:220-9. [PMID: 23413236 PMCID: PMC3567709 DOI: 10.1364/boe.4.000220] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/10/2012] [Revised: 11/29/2012] [Accepted: 11/30/2012] [Indexed: 05/25/2023]
Abstract
Optical side-effects of fs-laser treatment in refractive surgery are investigated by means of a model eye. We show that rainbow glare is the predominant perturbation, which can be avoided by randomly distributing laser spots within the lens. For corneal applications such as fs-LASIK, even a regular grid with spot-to-spot distances of ~3 µm is sufficient to minimize rainbow glare perception. Contrast sensitivity is affected, when the lens is treated with large 3D-patterns.
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Affiliation(s)
- Roland Ackermann
- Institute of Applied Physics, Abbe Center of Photonics,
Friedrich-Schiller-Universität Jena, Max-Wien-Platz 1, 07743 Jena,
Germany
| | - Robert Kammel
- Institute of Applied Physics, Abbe Center of Photonics,
Friedrich-Schiller-Universität Jena, Max-Wien-Platz 1, 07743 Jena,
Germany
| | - Marina Merker
- Institute of Applied Physics, Abbe Center of Photonics,
Friedrich-Schiller-Universität Jena, Max-Wien-Platz 1, 07743 Jena,
Germany
| | - Andreas Kamm
- Fraunhofer Institute for Applied Optics and Precision Engineering
(IOF), Albert-Einstein-Straße 7, 07745 Jena, Germany
| | - Andreas Tünnermann
- Institute of Applied Physics, Abbe Center of Photonics,
Friedrich-Schiller-Universität Jena, Max-Wien-Platz 1, 07743 Jena,
Germany
- Fraunhofer Institute for Applied Optics and Precision Engineering
(IOF), Albert-Einstein-Straße 7, 07745 Jena, Germany
| | - Stefan Nolte
- Institute of Applied Physics, Abbe Center of Photonics,
Friedrich-Schiller-Universität Jena, Max-Wien-Platz 1, 07743 Jena,
Germany
- Fraunhofer Institute for Applied Optics and Precision Engineering
(IOF), Albert-Einstein-Straße 7, 07745 Jena, Germany
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19
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Farjo AA, Sugar A, Schallhorn SC, Majmudar PA, Tanzer DJ, Trattler WB, Cason JB, Donaldson KE, Kymionis GD. Femtosecond lasers for LASIK flap creation: a report by the American Academy of Ophthalmology. Ophthalmology 2012; 120:e5-e20. [PMID: 23174396 DOI: 10.1016/j.ophtha.2012.08.013] [Citation(s) in RCA: 99] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2012] [Accepted: 08/07/2012] [Indexed: 11/19/2022] Open
Abstract
OBJECTIVE To review the published literature to assess the safety, efficacy, and predictability of femtosecond lasers for the creation of corneal flaps for LASIK; to assess the reported outcomes of LASIK when femtosecond lasers are used to create corneal flaps; and to compare the differences in outcomes between femtosecond lasers and mechanical microkeratomes. METHODS Literature searches of the PubMed and Cochrane Library databases were last conducted on October 12, 2011, without language or date limitations. The searches retrieved a total of 636 references. Of these, panel members selected 58 articles that they considered to be of high or medium clinical relevance, and the panel methodologist rated each article according to the strength of evidence. Four studies were rated as level I evidence, 14 studies were rated as level II evidence, and the remaining studies were rated as level III evidence. RESULTS The majority of published studies evaluated a single laser platform. Flap reproducibility varied by device and the generation of the device. Standard deviations in flap thicknesses ranged from 4 to 18.4 μm. Visual acuities and complications reported with LASIK flaps created using femtosecond lasers are within Food and Drug Administration safety and efficacy limits. Of all complications, diffuse lamellar keratitis is the most common after surgery but is generally mild and self-limited. Corneal sensation was reported to normalize by 1 year after surgery. Unique complications of femtosecond lasers included transient light-sensitivity syndrome, rainbow glare, opaque bubble layer, epithelial breakthrough of gas bubbles, and gas bubbles within the anterior chamber. CONCLUSIONS Available evidence (levels I and II) indicates that femtosecond lasers are efficacious devices for creating LASIK flaps, with accompanying good visual results. Overall, femtosecond lasers were found to be as good as or better than mechanical microkeratomes for creating LASIK flaps. There are unique complications that can occur with femtosecond lasers, and long-term follow-up is needed to evaluate the technology fully.
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Affiliation(s)
| | - Alan Sugar
- Ophthalmology and Visual Sciences, W.K. Kellogg Eye Center, University of Michigan, Ann Arbor, Michigan
| | - Steven C Schallhorn
- University of California, San Francisco, California; Global Medical Director Optical Express; Gordon-Weiss-Schanzlin Vision Institute, San Diego, California
| | | | - David J Tanzer
- Gordon-Weiss-Schanzlin Vision Institute, San Diego, California
| | | | - John B Cason
- Ophthalmology Clinic, Naval Medical Center, San Diego, California
| | | | - George D Kymionis
- Institute of Vision and Optics (IVO), Faculty of Medicine, University of Crete, Heraklion, Crete, Greece
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20
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Gualda EJ, Vázquez de Aldana JR, Martínez-García MC, Moreno P, Hernández-Toro J, Roso L, Artal P, Bueno JM. Femtosecond infrared intrastromal ablation and backscattering-mode adaptive-optics multiphoton microscopy in chicken corneas. BIOMEDICAL OPTICS EXPRESS 2011; 2:2950-60. [PMID: 22076258 PMCID: PMC3207366 DOI: 10.1364/boe.2.002950] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/01/2011] [Revised: 09/27/2011] [Accepted: 09/27/2011] [Indexed: 05/07/2023]
Abstract
The performance of femtosecond (fs) laser intrastromal ablation was evaluated with backscattering-mode adaptive-optics multiphoton microscopy in ex vivo chicken corneas. The pulse energy of the fs source used for ablation was set to generate two different ablation patterns within the corneal stroma at a certain depth. Intrastromal patterns were imaged with a custom adaptive-optics multiphoton microscope to determine the accuracy of the procedure and verify the outcomes. This study demonstrates the potential of using fs pulses as surgical and monitoring techniques to systematically investigate intratissue ablation. Further refinement of the experimental system by combining both functions into a single fs laser system would be the basis to establish new techniques capable of monitoring corneal surgery without labeling in real-time. Since the backscattering configuration has also been optimized, future in vivo implementations would also be of interest in clinical environments involving corneal ablation procedures.
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Affiliation(s)
- Emilio J. Gualda
- Laboratorio de Óptica, Centro de Investigación en Óptica y Nanofísica, Universidad de Murcia, Campus de Espinardo (Edificio 34), 30100 Murcia, Spain
| | - Javier R. Vázquez de Aldana
- Grupo de Investigación en Microprocesado de Materiales con Láser,Plaza de la Merced s/n, 37008 Salamanca, Spain
| | - M. Carmen Martínez-García
- Departamento Biología Celular, Histología y Farmacología,Facultad de Medicina, Universidad de Valladolid, Valladolid, Spain
| | - Pablo Moreno
- Grupo de Investigación en Microprocesado de Materiales con Láser,Plaza de la Merced s/n, 37008 Salamanca, Spain
| | - Juan Hernández-Toro
- Grupo de Investigación en Microprocesado de Materiales con Láser,Plaza de la Merced s/n, 37008 Salamanca, Spain
| | - Luis Roso
- Centro de Láseres Pulsados Ultracortos y Ultraintensos (CLPU), Plaza de la Merced s/n, 37008 Salamanca, Spain
| | - Pablo Artal
- Laboratorio de Óptica, Centro de Investigación en Óptica y Nanofísica, Universidad de Murcia, Campus de Espinardo (Edificio 34), 30100 Murcia, Spain
| | - Juan M. Bueno
- Laboratorio de Óptica, Centro de Investigación en Óptica y Nanofísica, Universidad de Murcia, Campus de Espinardo (Edificio 34), 30100 Murcia, Spain
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21
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Xu L, Knox WH, DeMagistris M, Wang N, Huxlin KR. Noninvasive intratissue refractive index shaping (IRIS) of the cornea with blue femtosecond laser light. Invest Ophthalmol Vis Sci 2011; 52:8148-55. [PMID: 21931133 DOI: 10.1167/iovs.11-7323] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
PURPOSE To test the feasibility of intratissue refractive index shaping (IRIS) in living corneas by using 400-nm femtosecond (fs) laser pulses (blue-IRIS). To test the hypothesis that the intrinsic two-photon absorption of the cornea allows blue-IRIS to be performed with greater efficacy than when using 800-nm femtosecond laser pulses. METHODS Fresh cat corneas were obtained postmortem and cut into six wedges. Blue laser pulses at 400 nm, with 100-fs pulse duration at 80 MHz were used to micromachine phase gratings into each corneal wedge at scanning speeds from 1 to 15 mm/s. Grating lines were 1 μm wide, 5 μm apart, and 150 μm below the anterior corneal surface. Refractive index (RI) changes in micromachined regions were measured immediately by recording the diffraction efficiency of inscribed gratings. Six hours later, the corneas were processed for histology, and TUNEL staining was performed to assess whether blue-IRIS causes cell death. RESULTS Scanning at 1 and 2 mm/s caused overt corneal damage in the form of bubbles and burns. At faster scanning speeds (5, 10, and 15 mm/s), phase gratings were created in the corneal stroma, which were shown to be pure RI changes ranging from 0.037 to 0.021 in magnitude. The magnitude of RI change was inversely related to scanning speed. TUNEL staining showed cell death only around bubbles and burns. CONCLUSIONS Blue-IRIS can be performed safely and effectively in living cornea. Compared with near-infrared laser pulses, blue-IRIS enhances both achievable RI change and scanning speed without the need to dope the tissue with two-photon sensitizers, increasing the clinical applicability of this technique.
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Affiliation(s)
- Lisen Xu
- The Institute of Optics, University of Rochester, Rochester, New York, USA
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Wang BG, König K, Halbhuber KJ. Two-photon microscopy of deep intravital tissues and its merits in clinical research. J Microsc 2010; 238:1-20. [PMID: 20384833 DOI: 10.1111/j.1365-2818.2009.03330.x] [Citation(s) in RCA: 141] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Multiphoton excitation laser scanning microscopy, relying on the simultaneous absorption of two or more photons by a molecule, is one of the most exciting recent developments in biomedical imaging. Thanks to its superior imaging capability of deeper tissue penetration and efficient light detection, this system becomes more and more an inspiring tool for intravital bulk tissue imaging. Two-photon excitation microscopy including 2-photon fluorescence and second harmonic generated signal microscopy is the most common multiphoton microscopic application. In the present review we take diverse ocular tissues as intravital samples to demonstrate the advantages of this approach. Experiments with registration of intracellular 2-photon fluorescence and extracellular collagen second harmonic generated signal microscopy in native ocular tissues are focused. Data show that the in-tandem combination of 2-photon fluorescence and second harmonic generated signal microscopy as two-modality microscopy allows for in situ co-localization imaging of various microstructural components in the whole-mount deep intravital tissues. New applications and recent developments of this high technology in clinical studies such as 2-photon-controlled drug release, in vivo drug screening and administration in skin and kidney, as well as its uses in tumourous tissues such as melanoma and glioma, in diseased lung, brain and heart are additionally reviewed. Intrinsic emission two-modal 2-photon microscopy/tomography, acting as an efficient and sensitive non-injurious imaging approach featured by high contrast and subcellular spatial resolution, has been proved to be a promising tool for intravital deep tissue imaging and clinical studies. Given the level of its performance, we believe that the non-linear optical imaging technique has tremendous potentials to find more applications in biomedical fundamental and clinical research in the near future.
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Affiliation(s)
- B-G Wang
- Laser Microscopy Research Unit, Institute of Microscopic Anatomy, Faculty of Medicine, Friedrich Schiller University of Jena. Teichgraben 7, 07743 Jena, Germany.
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