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1153 KiB

Open AccessArticle

Wide-Field OCT Angiography at 400 KHz Utilizing Spectral Splitting

by Laurin Ginner, Cedric Blatter, Daniel Fechtig, Tilman Schmoll, Martin Gröschl and Rainer A. Leitgeb

Photonics 2014, 1(4), 369-379; https://doi.org/10.3390/photonics1040369 - 23 Oct 2014

Cited by 19 | Viewed by 8940

Abstract

Optical angiography systems based on optical coherence tomography (OCT) require dense sampling in order to maintain good vascular contrast. We demonstrate a way to gain acquisition speed and spatial sampling by using spectral splitting with a swept source OCT system. This method splits [...] Read more.

Optical angiography systems based on optical coherence tomography (OCT) require dense sampling in order to maintain good vascular contrast. We demonstrate a way to gain acquisition speed and spatial sampling by using spectral splitting with a swept source OCT system. This method splits the recorded spectra into two to several subspectra. Using continuous lateral scanning, the lateral sampling is then increased by the same factor. This allows increasing the field of view of OCT angiography, while keeping the same transverse resolution and measurement time. The performance of our method is demonstrated in vivo at different locations of the human retina and verified quantitatively. Spectral splitting can be applied without any changes in the optical setup, thus offering an easy way to increase the field of view of OCT in general and in particular for OCT angiography. Full article

(This article belongs to the Special Issue Optics and Technologies for Ophthalmology and Visual Science)

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2467 KiB

Open AccessArticle

Infrared Retinoscopy

by Ying-Ling Chen, Lei Shi, James W. L. Lewis and Ming Wang

Photonics 2014, 1(4), 303-322; https://doi.org/10.3390/photonics1040303 - 3 Oct 2014

Cited by 4 | Viewed by 16106

Abstract

Infrared RetinoscopyRetinoscopy could be a more effective and versatile clinical tool in observing a wide range of ocular conditions if modifications were made to overcome the inherent difficulties. In this paper, a laboratory infrared retinoscope prototype was constructed to capture the digital images [...] Read more.

Infrared RetinoscopyRetinoscopy could be a more effective and versatile clinical tool in observing a wide range of ocular conditions if modifications were made to overcome the inherent difficulties. In this paper, a laboratory infrared retinoscope prototype was constructed to capture the digital images of the pupil reflex of various types of eye conditions. The captured low-contrast reflex images due to intraocular scattering were significantly improved with a simple image processing procedure for visualization. Detections of ocular aberrations were demonstrated, and computational models using patients’ wavefront data were built to simulate the measurement for comparison. The simulation results suggest that the retinal stray light that is strongly linked to intraocular scattering extend the detection range of illuminating eccentricity in retinoscopy and make it more likely to observe ocular aberrations. Full article

(This article belongs to the Special Issue Optics and Technologies for Ophthalmology and Visual Science)

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304 KiB

Open AccessCommunication

Clinical Trials of Exterior Non Implanted Interference-Based Extended Depth of Focus Intra Ocular Lens Design

by Zeev Zalevsky, Ido Raveh, Ofer Limon, Shai Ben Yaish, Karen Lahav Yacouel, Ravid Doron and Alex Zlotnik

Photonics 2014, 1(4), 296-302; https://doi.org/10.3390/photonics1040296 - 2 Oct 2014

Cited by 2 | Viewed by 5191

Abstract

In this paper, we present the clinical trials performed with intra ocular lens (IOL) design, realizing an interference-based extended depth of focus concept, with an external glass plate. The purpose of such extended depth of focus-based IOL design is to prevent cataract patients [...] Read more.

In this paper, we present the clinical trials performed with intra ocular lens (IOL) design, realizing an interference-based extended depth of focus concept, with an external glass plate. The purpose of such extended depth of focus-based IOL design is to prevent cataract patients from needing to use different types of glasses (for reading and for distance vision) after undergoing surgery. Full article

(This article belongs to the Special Issue Optics and Technologies for Ophthalmology and Visual Science)

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2093 KiB

Open AccessArticle

A Rapid and Convenient Procedure to Evaluate Optical Performance of Intraocular Lenses

by Frank Schaeffel and Hakan Kaymak

Photonics 2014, 1(3), 267-282; https://doi.org/10.3390/photonics1030267 - 18 Sep 2014

Cited by 1 | Viewed by 6018

Abstract

A new portable lens scanner was developed and tested for measuring focal lengths and relative contrast transfer of mono- and multifocal intraocular lenses (IOLs). A photograph of a natural scene was imaged in white light through an IOL in a water-filled cuvette, with [...] Read more.

A new portable lens scanner was developed and tested for measuring focal lengths and relative contrast transfer of mono- and multifocal intraocular lenses (IOLs). A photograph of a natural scene was imaged in white light through an IOL in a water-filled cuvette, with their +21D base power largely neutralized by a −20D trial lens, using a USB monochrome video camera that could be focused via a laptop-controlled stepping motor from −8.5 to + 8.0D. The output of 10000 ON-OFF antagonistic “receptive fields” measuring the video image with adjustable diameter was continuously recorded by custom written software to quantify focus and relative contrast. Six monofocal and four multifocal IOLs, as well as two radial refractive gradient (RRG) lenses were measured. After calibration with trial lenses the optical powers and relative contrast transfer of mono- and multifocal IOLs were readily measured. Refractive power profiles measured in RRG lenses closely matched data obtained from the manufacturer. The lens scanner uses a rapidly operating procedure, is portable and can be used to verify positions of the focal planes of mono- and multifocal IOLs in less than 3 s. Full article

(This article belongs to the Special Issue Optics and Technologies for Ophthalmology and Visual Science)

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368 KiB

Open AccessArticle

Preliminary Design and Evaluation of a B-Scan OCT-Guided Needle

by Karen M. Joos and Jin-Hui Shen

Photonics 2014, 1(3), 260-266; https://doi.org/10.3390/photonics1030260 - 12 Sep 2014

Cited by 7 | Viewed by 6089

Abstract

Real-time intraoperative B-scan optical coherence tomography (OCT) visualization of intraocular tissues is a desired ophthalmic feature during retinal procedures. A novel intraocular 25-gauge B-mode forward-imaging OCT probe was combined with a 36-gauge needle into a prototype instrument. Imaging of the needle tip itself [...] Read more.

Real-time intraoperative B-scan optical coherence tomography (OCT) visualization of intraocular tissues is a desired ophthalmic feature during retinal procedures. A novel intraocular 25-gauge B-mode forward-imaging OCT probe was combined with a 36-gauge needle into a prototype instrument. Imaging of the needle tip itself and the effects of saline injection into a gelatin phantom were performed. A combined B-scan forward-imaging OCT-needle prototype was capable of real-time-imaging of saline injection into a gelatin phantom. Additional future miniaturization may permit this instrument to be an adjunctive real-time imaging and procedure tool for vitreoretinal surgery. Full article

(This article belongs to the Special Issue Optics and Technologies for Ophthalmology and Visual Science)

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360 KiB

Open AccessArticle

Photostress Testing Device for Diagnosing Retinal Disease

by Elizabeth Swan, Jim Schwiegerling, Gholam Peyman and Eniko Enikov

Photonics 2014, 1(3), 211-219; https://doi.org/10.3390/photonics1030211 - 8 Aug 2014

Cited by 1 | Viewed by 5502

Abstract

Retinal diseases such as Age-Related Macular Degeneration (ARMD) affect nearly one in three elderly patients. ARMD damages the central vision photoreceptors in the fovea. The Photostress Test is a simple technique for testing for the early effects of ARMD. Here, the illumination sources [...] Read more.

Retinal diseases such as Age-Related Macular Degeneration (ARMD) affect nearly one in three elderly patients. ARMD damages the central vision photoreceptors in the fovea. The Photostress Test is a simple technique for testing for the early effects of ARMD. Here, the illumination sources in a novel self-administered Photostress Testing device were modeled for safety and distribution in illumination software. After satisfying the design constraints in the model, a prototype of the illumination system was fabricated and tested to confirm the modeling results. The resultant prototype can be used to aid in the diagnosis of retinal disease and is well within retinal safety levels. Full article

(This article belongs to the Special Issue Optics and Technologies for Ophthalmology and Visual Science)

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Review

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541 KiB

Open AccessReview

The Role of Ultraviolet Radiation in the Ocular System of Mammals

by Mercede Majdi, Behrad Y. Milani, Asadolah Movahedan, Lisa Wasielewski and Ali R. Djalilian

Photonics 2014, 1(4), 347-368; https://doi.org/10.3390/photonics1040347 - 22 Oct 2014

Cited by 12 | Viewed by 15642

Abstract

With decreasing levels of ozone in the atmosphere, we are being exposed to higher levels of ultraviolet radiation (UVR) than ever before. UVR carries higher energy than visible light, and its effects on tissues include DNA damage, gene mutations, immunosuppression, oxidative stress and [...] Read more.

With decreasing levels of ozone in the atmosphere, we are being exposed to higher levels of ultraviolet radiation (UVR) than ever before. UVR carries higher energy than visible light, and its effects on tissues include DNA damage, gene mutations, immunosuppression, oxidative stress and inflammatory responses. In the eye, UVR is strongly associated with the development of basal and squamous cell carcinoma of the eyelid, pterygium, photokeratitis, climatic droplet keratopathy, ocular surface squamous neoplasia, cataracts, and uveal melanoma, and is weakly associated with age-related macular degeneration. Despite overwhelming evidence regarding the deleterious effects on UVR, public health measures to encourage UV protection of the eyes is generally lacking. Options for photoprotection include sunglasses, wide brim hats, windshields, plastic films for side windows in cars, UV blocking contact lenses, and following the UV Index report daily. The American National Standards Institute currently has regulations regarding properties of UV blocking sunglasses; however, compliance in the US is not mandatory. On the other hand, UVR does have therapeutic applications in the eye, particularly, riboflavin activated by ultraviolet A light (UVA) radiation is used clinically to slow the progression of keratoconus, post-LASIK keratectasia, and bullous keratopathy by crosslinking corneal collagen fibers. Additionally, riboflavin activated by UVA has been shown to have antibacterial, antiviral, and antiparasitic effects. This is clinically relevant in the treatment of infectious keratitis. Finally, exposure to low levels of light in the UV spectrum has been found to regulate the growth of the eye and lack of adequate exposure may increase the risk of development and progression of myopia. Full article

(This article belongs to the Special Issue Optics and Technologies for Ophthalmology and Visual Science)

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918 KiB

Open AccessReview

Basic Technology and Clinical Applications of the Updated Model of Laser Speckle Flowgraphy to Ocular Diseases

by Tetsuya Sugiyama

Photonics 2014, 1(3), 220-234; https://doi.org/10.3390/photonics1030220 - 12 Aug 2014

Cited by 93 | Viewed by 11366

Abstract

Laser speckle flowgraphy (LSFG) allows for quantitative estimation of blood flow in the optic nerve head (ONH), choroid and retina, utilizing the laser speckle phenomenon. The basic technology and clinical applications of LSFG-NAVI, the updated model of LSFG, are summarized in this review. [...] Read more.

Laser speckle flowgraphy (LSFG) allows for quantitative estimation of blood flow in the optic nerve head (ONH), choroid and retina, utilizing the laser speckle phenomenon. The basic technology and clinical applications of LSFG-NAVI, the updated model of LSFG, are summarized in this review. For developing a commercial version of LSFG, the special area sensor was replaced by the ordinary charge-coupled device camera. In LSFG-NAVI, the mean blur rate (MBR) has been introduced as a new parameter. Compared to the original LSFG model, LSFG-NAVI demonstrates a better spatial resolution of the blood flow map of human ocular fundus. The observation area is 24 times larger than the original system. The analysis software can separately calculate MBRs in the blood vessels and tissues (capillaries) of an entire ONH and the measurements have good reproducibility. The absolute values of MBR in the ONH have been shown to linearly correlate with the capillary blood flow. The Analysis of MBR pulse waveform provides parameters including skew, blowout score, blowout time, rising and falling rates, flow acceleration index, acceleration time index, and resistivity index for comparing different eyes. Recently, there have been an increasing number of reports on the clinical applications of LSFG-NAVI to ocular diseases, including glaucoma, retinal and choroidal diseases. Full article

(This article belongs to the Special Issue Optics and Technologies for Ophthalmology and Visual Science)

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