The Experts below are selected from a list of 16491 Experts worldwide ranked by ideXlab platform
Srinivas R Sadda - One of the best experts on this subject based on the ideXlab platform.
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Distribution of peripheral lesions identified by mydriatic ultra-wide field Fundus Imaging in diabetic retinopathy
Graefe's Archive for Clinical and Experimental Ophthalmology, 2020Co-Authors: Aditya Verma, Srinivas R Sadda, Ahmed Roshdy Alagorie, Kim Ramasamy, Jano Hemert, Nk Yadav, Rajeev R Pappuru, Adnan Tufail, Muneesawar Gupta Nittala, Rajiv RamanAbstract:Purpose To analyze the distribution of diabetic retinopathy (DR) lesions in an Indian population using ultra-wide field (UWF) Fundus Imaging. Methods Seven hundred fifteen subjects (1406 eyes) with diabetic retinopathy in India were enrolled in this multicenter, prospective, observational study using UWF pseudocolor Imaging with Optos Daytona Plus (Optos plc, Dunfermline, Scotland, UK). Images were transmitted to Doheny Image Reading Center, Los Angeles, CA, for grading. The ETDRS grid was overlaid on stereographic projections of UWF images, and images were graded independently by 2 masked graders. Lesion distribution was graded as predominantly central (PCL) or predominantly peripheral (PPL) according to previous criteria, considering both lesion number and area. An image was graded as PPL if > 50% of the lesion area was seen in at least one peripheral field as compared with the corresponding ETDRS field. Diabetic retinopathy severity was also assessed based on the International Classification of Diabetic Retinopathy (ICDR) grading scale. The main outcome measures were lesion distribution (PPL versus PCL): overall and within specific fields in eyes with various grades of DR. Results Lesion distribution was rated to be PPL in 37% of eyes and PCL in 63% of eyes ( P
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ultra widefield Fundus Imaging a review of clinical applications and future trends
Retina-the Journal of Retinal and Vitreous Diseases, 2016Co-Authors: Aaron Nagiel, Robert A Lalane, Srinivas R Sadda, Steven D SchwartzAbstract:Purpose:To review the basic principles of ultra-widefield Fundus Imaging and discuss its clinical utility for a variety of retinal and choroidal disorders.Methods:A systematic review of the PubMed database was performed using the search terms Optos, optomap, panoramic, ultra-widefield, wide-angle, a
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comparison of drusen area detected by spectral domain optical coherence tomography and color Fundus Imaging
Investigative Ophthalmology & Visual Science, 2013Co-Authors: Zohar Yehoshua, Srinivas R Sadda, Giovanni Gregori, Fernando M Penha, Raquel Goldhardt, Muneeswar Gupta Nittala, Ranjith Konduru, William J Feuer, Pooja Gupta, Philip J. RosenfeldAbstract:PURPOSE To compare the measurements of drusen area from manual segmentation of color Fundus photographs with those generated by an automated algorithm designed to detect elevations of the retinal pigment epithelium (RPE) on spectral domain optical coherence tomography (SD-OCT) images. METHODS Fifty eyes with drusen secondary to nonexudative age-related macular degeneration were enrolled. All eyes were imaged with a high-definition OCT instrument using a 200 × 200 A-scan raster pattern covering a 6 mm × 6 mm area centered on the fovea. Digital color Fundus images were taken on the same day. Drusen were traced manually on the Fundus photos by graders at the Doheny Image Reading Center, whereas quantitative OCT measurements of drusen were obtained by using a fully automated algorithm. The color Fundus images were registered to the OCT data set and measurements within corresponding 3- and 5-mm circles centered at the fovea were compared. RESULTS The mean areas (± SD [range]) for the 3-mm circles were SD-OCT = 1.57 (± 1.08 [0.03-4.44]); 3-mm color Fundus = 1.92 (± 1.08 [0.20-3.95]); 5-mm SD-OCT = 2.12 (± 1.55 [0.03-5.40]); and 5-mm color Fundus = 3.38 (± 1.90 [0.39-7.49]). The mean differences between color images and the SD-OCT (color - SD-OCT) were 0.36 (± 0.93) (P = 0.008) for the 3-mm circle and 1.26 (± 1.38) (P < 0.001) for the 5-mm circle measurements. Intraclass correlation coefficients of agreements for 3- and 5-mm measurements were 0.599 and 0.540, respectively. CONCLUSIONS There was only fair agreement between drusen area measurements obtained from SD-OCT images and color Fundus photos. Drusen area measurements on color Fundus images were larger than those with SD-OCT scans. This difference can be attributed to the fact that the OCT algorithm defines drusen in terms of RPE deformations above a certain threshold, and will not include small, flat drusen and subretinal drusenoid deposits. The two approaches provide complementary information about drusen.
Xincheng Yao - One of the best experts on this subject based on the ideXlab platform.
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Wide-field Fundus Imaging with trans-palpebral illumination
Proceedings of SPIE--the International Society for Optical Engineering, 2017Co-Authors: Devrim Toslak, Damber Thapa, Yanjun Chen, Muhammet Kazim Erol, R. V. Paul Chan, Xincheng YaoAbstract:In conventional Fundus Imaging devices, transpupillary illumination is used for illuminating the inside of the eye. In this method, the illumination light is directed into the posterior segment of the eye through the cornea and passes the pupillary area. As a result of sharing the pupillary area for the illumination beam and observation path, pupil dilation is typically necessary for wide-angle Fundus examination, and the field of view is inherently limited. An alternative approach is to deliver light from the sclera. It is possible to image a wider retinal area with transcleral-illumination. However, the requirement of physical contact between the illumination probe and the sclera is a drawback of this method. We report here trans-palpebral illumination as a new method to deliver the light through the upper eyelid (palpebra). For this study, we used a 1.5 mm diameter fiber with a warm white LED light source. To illuminate the inside of the eye, the fiber illuminator was placed at the location corresponding to the pars plana region. A custom designed optical system was attached to a digital camera for retinal Imaging. The optical system contained a 90 diopter ophthalmic lens and a 25 diopter relay lens. The ophthalmic lens collected light coming from the posterior of the eye and formed an aerial image between the ophthalmic and relay lenses. The aerial image was captured by the camera through the relay lens. An adequate illumination level was obtained to capture wide angle Fundus images within ocular safety limits, defined by the ISO 15004-2: 2007 standard. This novel trans-palpebral illumination approach enables wide-angle Fundus photography without eyeball contact and pupil dilation.
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trans palpebral illumination an approach for wide angle Fundus photography without the need for pupil dilation
Optics Letters, 2016Co-Authors: Devrim Toslak, Damber Thapa, Yanjun Chen, Muhammet Kazim Erol, R Paul V Chan, Xincheng YaoAbstract:It is technically difficult to construct wide-angle Fundus Imaging devices due to the complexity of conventional transpupillary illumination and Imaging mechanisms. We report here a new method, i.e., trans-palpebral illumination, for wide-angle Fundus photography without the need for pupil dilation. By constructing a smartphone-based prototype Imaging device, we demonstrated a 152° view in a single-shot image. The unique combination of low-cost smartphone design and automatic illumination optimization promises an affordable solution to conduct telemedicine assessment of eye diseases, which will improve access to eye care for patients in rural and underserved areas.
Steven D Schwartz - One of the best experts on this subject based on the ideXlab platform.
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ultra widefield Fundus Imaging a review of clinical applications and future trends
Retina-the Journal of Retinal and Vitreous Diseases, 2016Co-Authors: Aaron Nagiel, Robert A Lalane, Srinivas R Sadda, Steven D SchwartzAbstract:Purpose:To review the basic principles of ultra-widefield Fundus Imaging and discuss its clinical utility for a variety of retinal and choroidal disorders.Methods:A systematic review of the PubMed database was performed using the search terms Optos, optomap, panoramic, ultra-widefield, wide-angle, a
Devrim Toslak - One of the best experts on this subject based on the ideXlab platform.
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Wide-field Fundus Imaging with trans-palpebral illumination
Proceedings of SPIE--the International Society for Optical Engineering, 2017Co-Authors: Devrim Toslak, Damber Thapa, Yanjun Chen, Muhammet Kazim Erol, R. V. Paul Chan, Xincheng YaoAbstract:In conventional Fundus Imaging devices, transpupillary illumination is used for illuminating the inside of the eye. In this method, the illumination light is directed into the posterior segment of the eye through the cornea and passes the pupillary area. As a result of sharing the pupillary area for the illumination beam and observation path, pupil dilation is typically necessary for wide-angle Fundus examination, and the field of view is inherently limited. An alternative approach is to deliver light from the sclera. It is possible to image a wider retinal area with transcleral-illumination. However, the requirement of physical contact between the illumination probe and the sclera is a drawback of this method. We report here trans-palpebral illumination as a new method to deliver the light through the upper eyelid (palpebra). For this study, we used a 1.5 mm diameter fiber with a warm white LED light source. To illuminate the inside of the eye, the fiber illuminator was placed at the location corresponding to the pars plana region. A custom designed optical system was attached to a digital camera for retinal Imaging. The optical system contained a 90 diopter ophthalmic lens and a 25 diopter relay lens. The ophthalmic lens collected light coming from the posterior of the eye and formed an aerial image between the ophthalmic and relay lenses. The aerial image was captured by the camera through the relay lens. An adequate illumination level was obtained to capture wide angle Fundus images within ocular safety limits, defined by the ISO 15004-2: 2007 standard. This novel trans-palpebral illumination approach enables wide-angle Fundus photography without eyeball contact and pupil dilation.
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trans palpebral illumination an approach for wide angle Fundus photography without the need for pupil dilation
Optics Letters, 2016Co-Authors: Devrim Toslak, Damber Thapa, Yanjun Chen, Muhammet Kazim Erol, R Paul V Chan, Xincheng YaoAbstract:It is technically difficult to construct wide-angle Fundus Imaging devices due to the complexity of conventional transpupillary illumination and Imaging mechanisms. We report here a new method, i.e., trans-palpebral illumination, for wide-angle Fundus photography without the need for pupil dilation. By constructing a smartphone-based prototype Imaging device, we demonstrated a 152° view in a single-shot image. The unique combination of low-cost smartphone design and automatic illumination optimization promises an affordable solution to conduct telemedicine assessment of eye diseases, which will improve access to eye care for patients in rural and underserved areas.
David E Newby - One of the best experts on this subject based on the ideXlab platform.
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association between hypertension and retinal vascular features in ultra widefield Fundus Imaging
Open Heart, 2020Co-Authors: Gavin Robertson, Alan Fleming, Michelle C Williams, Emanuele Trucco, Nicola Quinn, Ruth E Hogg, Gareth J Mckay, Ian S Young, Enrico Pellegrini, David E NewbyAbstract:Objective Changes to the retinal vasculature are known to be associated with hypertension independently of traditional risk factors. We investigated whether measurements of retinal vascular calibre from ultra-widefield Fundus Imaging were associated with hypertensive status. Methods We retrospectively collected and semiautomatically measured ultra-widefield retinal Fundus images from a subset of participants enrolled in an ongoing population study of ageing, categorised as normotensive or hypertensive according to thresholds on systolic/diastolic blood pressure (140/90 mm Hg) measured in a clinical setting. Vascular calibre in the peripheral retina was measured to calculate the nasal–annular arteriole:venule ratio (NA-AVR), a novel combined parameter. Results Left and right eyes were analysed from 440 participants (aged 50–59 years, mean age of 54.6±2.9 years, 247, 56.1% women), including 151 (34.3%) categorised as hypertensive. Arterioles were thinner and the NA-AVR was smaller in people with hypertension. The area under the receiver operating characteristic curve of NA-AVR for hypertensive status was 0.73 (95% CI 0.68 to 0.78) using measurements from left eyes, while for right eyes, it was 0.64 (95% CI 0.59 to 0.70), representing evidence of a statistically significant difference between the eyes (p=0.020). Conclusions Semiautomated measurements of NA-AVR in ultra-widefield Fundus Imaging were associated with hypertension. With further development, this may help screen people attending routine eye health check-ups for high blood pressure. These individuals may then follow a care pathway for suspected hypertension. Our results showed differences between left and right eyes, highlighting the importance of investigating both eyes of a patient.
