The Experts below are selected from a list of 327 Experts worldwide ranked by ideXlab platform
Tin Aung - One of the best experts on this subject based on the ideXlab platform.
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Peripapillary choroidal thickness assessed using automated choroidal segmentation software in an Asian population
British Journal of Ophthalmology, 2015Co-Authors: Preeti Gupta, Gemmy C.m. Cheung, Ecosse L Lamoureux, Carol Y. Cheung, Tian Jing, Mani Baskaran, Pina Marziliano, Tien Yin Wong, Tin Aung, Ching-yu ChengAbstract:AIMS: To objectively quantify the thickness of peripapillary choroid using spectral-domain optical coherence tomography (SD-OCT) with enhanced depth imaging (EDI) followed by a novel automated choroidal segmentation software in Asian eyes and to evaluate its systemic and ocular determinants. METHODS: We recruited 520 subjects (1040 eyes) from the Singapore Malay Eye Study, a cross-sectional population-based study. Subjects underwent standardised detailed ophthalmic examination including SD-OCT (Spectralis) with EDI for measurement of peripapillary choroidal thickness (PPCT). RESULTS: The mean age of the subjects was 66.7+/-10.4 years (range 47-88 years) and the mean spherical equivalent was -0.01+/-2.28 D (range -18.50 to +7.00 D). The intra-session repeatability of PPCT measurements at four Quadrants using automated choroidal segmentation software was excellent (intraclass correlation coefficient 0.9998-0.9999). The overall mean PPCT was 136.2+/-56.8 microm. Peripapillary choroid showed geographical differences among the four Quadrants, being thickest in the superior Quadrant (150.5+/-59.6 microm), followed by the nasal (143.5+/-58.4 microm) and temporal Quadrants (139.4+/-68.9 microm), and thinnest in the inferior Quadrant (111.3+/-51.7 microm). Among the range of ocular and systemic factors studied, shorter axial length (p=0.002), younger age (p=0.018), lower triglyceride level (p=0.015) and the presence of diabetes (p=0.036) were the only significant predictors of thicker peripapillary choroid. CONCLUSIONS: Using novel automated choroidal segmentation software, we provide reliable objective measurements of PPCT in a population-based setting. Shorter axial length, younger age, lower triglyceride levels and the presence of diabetes are the factors independently associated with thicker PPCT. These factors should be taken into consideration when interpreting Spectralis EDI SD-OCT-based PPCT measurements in clinics.
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Changes in angle configuration after phacoemulsification measured by anterior segment optical coherence tomography.
Journal of Glaucoma, 2008Co-Authors: Winifred P. Nolan, David S Friedman, Ce Zheng, Scott D. Smith, David Huang, Paul J Foster, Tin Aung, Yiong Huak Chan, Paul T.k. ChewAbstract:Purpose: To measure changes in angle width after phacoemulsification and intraocular lens (IOL) implantation using anterior segment optical coherence tomography (AS-OCT). Materials and Methods: Twenty-one patients undergoing cataract surgery were recruited from the National University Hospital, Singapore. AS-OCT images were obtained of nasal and temporal angle Quadrants before and at 1-month after surgery. Optical measurements of central anterior chamber depth were obtained, and gonioscopic measurement of angle width was recorded. AS-OCT angle width parameters measured in the nasal and temporal Quadrants included the angle opening distance at 500mm (AOD500) anterior to the scleral spur and the trabecular iris surface area at 750mm (TISA750) anterior to the scleral spur. Preoperative and postoperative measurements were compared using paired samples t tests. Results: Data were collected from 21 eyes of 21 subjects with cataract. Seven subjects also had gonioscopic evidence of primary angle closure. Mean anterior chamber depth increased from 2.92 ( ± 0.54) to 4.24 ( ± 0.57) mm (P = 0.044) after cataract extraction. There was a significant increase in AS-OCT parameters for both nasal and temporal angles after surgery. An 88.2% increase in AOD500 was measured for the nasal angle Quadrant with a mean difference of 213.9 ( ± 173)mm (P
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comparison of gonioscopy and anterior segment ocular coherence tomography in detecting angle closure in different Quadrants of the anterior chamber angle
Ophthalmology, 2008Co-Authors: Lisandro M Sakata, David S Friedman, Paul J Foster, Raghavan Lavanya, Han T Aung, Rajesh S Kumar, Tin AungAbstract:Purpose To compare the performance of gonioscopy and anterior segment (AS) optical coherence tomography (OCT) in detecting angle closure in the different Quadrants of the anterior chamber angle (ACA). Design Cross-sectional observational study. Participants Five hundred two consecutive subjects more than 50 years of age with no previous ophthalmic problems recruited from a community clinic in Singapore. Methods All subjects underwent gonioscopy and AS OCT imaging in the dark. Using gonioscopy, the ACA was graded using the Scheie system by a single examiner masked to AS OCT findings. Main Outcome Measures The ACA in a particular Quadrant was classified as closed if the posterior trabecular meshwork could not be seen on gonioscopy. A closed ACA on AS OCT imaging was defined by the presence of any contact between the iris and angle wall anterior to the scleral spur. Results After excluding eyes with poor image quality, a total of 423 right eyes were included in the analysis. A closed angle in at least 1 Quadrant was observed in 59% of the eyes by AS OCT and in 33% of the eyes by gonioscopy ( P Conclusions The highest rates of closed angles on gonioscopy and AS OCT images were observed in the superior Quadrant. Anterior segment OCT tended to detect more closed ACAs than gonioscopy, particularly in the superior and inferior Quadrants. Variations in the iris profile and level of iridoangle contact also may explain some of the differences seen between gonioscopy and AS OCT.
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Comparison of gonioscopy and anterior segment ocular coherence tomography in detecting angle closure in different Quadrants of the anterior chamber angle
OPHTHALMOLOGY, 2008Co-Authors: Tin AungAbstract:Purpose: To compare the performance of gonioscopy and anterior segment (AS) optical coherence tomography (OCT) in detecting angle closure in the different Quadrants of the anterior chamber angle (ACA).Design: Cross-sectional observational study.Participants: Five hundred two consecutive subjects more than 50 years of age with no previous ophthalmic problems recruited from a community clinic in Singapore.Methods: All subjects underwent gonioscopy and AS OCT imaging in the dark. Using gonioscopy, the ACA was graded using the Scheie system by a single examiner masked to AS OCT findings.Main Outcome Measures: The ACA in a particular Quadrant was classified as closed if the posterior trabecular meshwork could not be seen on gonioscopy. A closed ACA on AS OCT imaging was defined by the presence of any contact between the iris and angle wall anterior to the scleral spur.Results: After excluding eyes with poor image quality, a total of 423 right eyes were included in the analysis. A closed angle in at least 1 Quadrant was observed in 59% of the eyes by AS OCT and in 33% of the eyes by gonioscopy (P
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reproducibility of anterior chamber angle measurements obtained with anterior segment optical coherence tomography
Investigative Ophthalmology & Visual Science, 2007Co-Authors: Sunita Radhakrishnan, David S Friedman, Scott D. Smith, Winifred P. Nolan, David Huang, Tin Aung, Zheng Ce, Yan Li, Paul T.k. ChewAbstract:PURPOSE. To evaluate the reproducibility of anterior chamber (AC) angle measurements obtained using anterior segment optical coherence tomography (AS-OCT). METHODS. Patients with suspected glaucoma and those with glaucoma, ocular hypertension, or anatomically narrow angles were recruited from the glaucoma service at the National University Hospital, Singapore. All subjects underwent imaging of the nasal, temporal, and inferior AC angles with an AS-OCT prototype under standardized dark and light conditions. For short-term reproducibility analysis, a single observer acquired two sets of images followed by a third set of images acquired by a second observer. The interval between sessions was 10 minutes. For long-term reproducibility analysis, a single observer acquired two sets of images at least 24 hours apart. Images were measured using custom software to determine the AC depth (ACD), angle opening distance at 500 m (AOD500), angle recess area at 500 m (ARA500), and trabecular–iris space area at 500 m (TISA500). The intraclass correlation coefficient (ICC) was calculated as a measure of intraobserver and interobserver reproducibility. RESULTS. Twenty eyes of 20 patients were analyzed for shortterm reproducibility, and 23 eyes of 23 patients were analyzed for long-term reproducibility. AC depth measurement demonstrated excellent reproducibility (ICC 0.93–1.00) in both dark and light conditions. For the nasal and temporal Quadrants, all AC angle parameters demonstrated good to excellent shortterm (ICC 0.67– 0.90) and long-term (ICC 0.56 – 0.93) reproducibility in both dark and light conditions. In the inferior Quadrant, reproducibility was lower in all categories of analysis and varied from poor to good (ICC 0.31– 0.73). CONCLUSIONS. AS-OCT allows quantitative assessment of the AC angle. The reproducibility of AC angle measurements was good to excellent for the nasal and temporal Quadrants. The lower reproducibility of measurements in the inferior Quadrant may be unique to this prototype due to difficulty in acquiring high-quality images of the inferior angle. Further assessment of the commercially available AS-OCT is needed to clarify this finding. (Invest Ophthalmol Vis Sci. 2007;48:3683–3688) DOI: 10.1167/iovs.06-1120
Joseph Ho - One of the best experts on this subject based on the ideXlab platform.
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analysis of normal peripapillary choroidal thickness via spectral domain optical coherence tomography
Ophthalmology, 2011Co-Authors: Lauren Branchini, Caio V Regatieri, Chandrasekharan Krishnan, James G Fujimoto, Joseph Ho, Jay S DukerAbstract:Purpose To analyze the normal peripapillary choroidal thickness utilizing a commercial spectral domain optical coherence tomography (OCT) device and determine the intergrader reproducibility of this method. Design Retrospective, noncomparative, noninterventional case series. Participants Thirty-six eyes of 36 normal patients seen at the New England Eye Center between April and September 2010. Methods All patients underwent high-definition scanning with the Cirrus HD-OCT. Two raster scans were obtained per eye, a horizontal and a vertical scan, both of which were centered at the optic nerve. Two independent graders individually measured the choroidal thickness. Choroidal thickness was measured from the posterior edge of the retinal pigment epithelium to the choroid–scleral junction at 500-μm intervals away from the optic nerve in the superior, inferior, nasal, and temporal Quadrants. Statistical analysis was conducted to compare mean choroidal thicknesses. Intergrader reproducibility was assessed by intraclass correlation coefficient and Pearson's correlation coefficient. Average choroidal thickness in each Quadrant was compared with retinal nerve fiber layer (RNFL) thickness in their respective Quadrants. Main Outcome Measures Peripapillary choroidal thickness, intraclass coefficient, and Pearson's correlation coefficient. Results The peripapillary choroid in the inferior Quadrant was significantly thinner compared with all other Quadrants ( P P P Conclusions Manual segmentation of the peripapillary choroidal thickness is reproducible between graders, suggesting that this method is accurate. The inferior peripapillary choroid was significantly thinner than all other Quadrants ( P Financial Disclosure(s) Proprietary or commercial disclosure may be found after the references.
David S Friedman - One of the best experts on this subject based on the ideXlab platform.
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Changes in angle configuration after phacoemulsification measured by anterior segment optical coherence tomography.
Journal of Glaucoma, 2008Co-Authors: Winifred P. Nolan, David S Friedman, Ce Zheng, Scott D. Smith, David Huang, Paul J Foster, Tin Aung, Yiong Huak Chan, Paul T.k. ChewAbstract:Purpose: To measure changes in angle width after phacoemulsification and intraocular lens (IOL) implantation using anterior segment optical coherence tomography (AS-OCT). Materials and Methods: Twenty-one patients undergoing cataract surgery were recruited from the National University Hospital, Singapore. AS-OCT images were obtained of nasal and temporal angle Quadrants before and at 1-month after surgery. Optical measurements of central anterior chamber depth were obtained, and gonioscopic measurement of angle width was recorded. AS-OCT angle width parameters measured in the nasal and temporal Quadrants included the angle opening distance at 500mm (AOD500) anterior to the scleral spur and the trabecular iris surface area at 750mm (TISA750) anterior to the scleral spur. Preoperative and postoperative measurements were compared using paired samples t tests. Results: Data were collected from 21 eyes of 21 subjects with cataract. Seven subjects also had gonioscopic evidence of primary angle closure. Mean anterior chamber depth increased from 2.92 ( ± 0.54) to 4.24 ( ± 0.57) mm (P = 0.044) after cataract extraction. There was a significant increase in AS-OCT parameters for both nasal and temporal angles after surgery. An 88.2% increase in AOD500 was measured for the nasal angle Quadrant with a mean difference of 213.9 ( ± 173)mm (P
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comparison of gonioscopy and anterior segment ocular coherence tomography in detecting angle closure in different Quadrants of the anterior chamber angle
Ophthalmology, 2008Co-Authors: Lisandro M Sakata, David S Friedman, Paul J Foster, Raghavan Lavanya, Han T Aung, Rajesh S Kumar, Tin AungAbstract:Purpose To compare the performance of gonioscopy and anterior segment (AS) optical coherence tomography (OCT) in detecting angle closure in the different Quadrants of the anterior chamber angle (ACA). Design Cross-sectional observational study. Participants Five hundred two consecutive subjects more than 50 years of age with no previous ophthalmic problems recruited from a community clinic in Singapore. Methods All subjects underwent gonioscopy and AS OCT imaging in the dark. Using gonioscopy, the ACA was graded using the Scheie system by a single examiner masked to AS OCT findings. Main Outcome Measures The ACA in a particular Quadrant was classified as closed if the posterior trabecular meshwork could not be seen on gonioscopy. A closed ACA on AS OCT imaging was defined by the presence of any contact between the iris and angle wall anterior to the scleral spur. Results After excluding eyes with poor image quality, a total of 423 right eyes were included in the analysis. A closed angle in at least 1 Quadrant was observed in 59% of the eyes by AS OCT and in 33% of the eyes by gonioscopy ( P Conclusions The highest rates of closed angles on gonioscopy and AS OCT images were observed in the superior Quadrant. Anterior segment OCT tended to detect more closed ACAs than gonioscopy, particularly in the superior and inferior Quadrants. Variations in the iris profile and level of iridoangle contact also may explain some of the differences seen between gonioscopy and AS OCT.
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reproducibility of anterior chamber angle measurements obtained with anterior segment optical coherence tomography
Investigative Ophthalmology & Visual Science, 2007Co-Authors: Sunita Radhakrishnan, David S Friedman, Scott D. Smith, Winifred P. Nolan, David Huang, Tin Aung, Zheng Ce, Yan Li, Paul T.k. ChewAbstract:PURPOSE. To evaluate the reproducibility of anterior chamber (AC) angle measurements obtained using anterior segment optical coherence tomography (AS-OCT). METHODS. Patients with suspected glaucoma and those with glaucoma, ocular hypertension, or anatomically narrow angles were recruited from the glaucoma service at the National University Hospital, Singapore. All subjects underwent imaging of the nasal, temporal, and inferior AC angles with an AS-OCT prototype under standardized dark and light conditions. For short-term reproducibility analysis, a single observer acquired two sets of images followed by a third set of images acquired by a second observer. The interval between sessions was 10 minutes. For long-term reproducibility analysis, a single observer acquired two sets of images at least 24 hours apart. Images were measured using custom software to determine the AC depth (ACD), angle opening distance at 500 m (AOD500), angle recess area at 500 m (ARA500), and trabecular–iris space area at 500 m (TISA500). The intraclass correlation coefficient (ICC) was calculated as a measure of intraobserver and interobserver reproducibility. RESULTS. Twenty eyes of 20 patients were analyzed for shortterm reproducibility, and 23 eyes of 23 patients were analyzed for long-term reproducibility. AC depth measurement demonstrated excellent reproducibility (ICC 0.93–1.00) in both dark and light conditions. For the nasal and temporal Quadrants, all AC angle parameters demonstrated good to excellent shortterm (ICC 0.67– 0.90) and long-term (ICC 0.56 – 0.93) reproducibility in both dark and light conditions. In the inferior Quadrant, reproducibility was lower in all categories of analysis and varied from poor to good (ICC 0.31– 0.73). CONCLUSIONS. AS-OCT allows quantitative assessment of the AC angle. The reproducibility of AC angle measurements was good to excellent for the nasal and temporal Quadrants. The lower reproducibility of measurements in the inferior Quadrant may be unique to this prototype due to difficulty in acquiring high-quality images of the inferior angle. Further assessment of the commercially available AS-OCT is needed to clarify this finding. (Invest Ophthalmol Vis Sci. 2007;48:3683–3688) DOI: 10.1167/iovs.06-1120
Lisandro M Sakata - One of the best experts on this subject based on the ideXlab platform.
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comparison of gonioscopy and anterior segment ocular coherence tomography in detecting angle closure in different Quadrants of the anterior chamber angle
Ophthalmology, 2008Co-Authors: Lisandro M Sakata, David S Friedman, Paul J Foster, Raghavan Lavanya, Han T Aung, Rajesh S Kumar, Tin AungAbstract:Purpose To compare the performance of gonioscopy and anterior segment (AS) optical coherence tomography (OCT) in detecting angle closure in the different Quadrants of the anterior chamber angle (ACA). Design Cross-sectional observational study. Participants Five hundred two consecutive subjects more than 50 years of age with no previous ophthalmic problems recruited from a community clinic in Singapore. Methods All subjects underwent gonioscopy and AS OCT imaging in the dark. Using gonioscopy, the ACA was graded using the Scheie system by a single examiner masked to AS OCT findings. Main Outcome Measures The ACA in a particular Quadrant was classified as closed if the posterior trabecular meshwork could not be seen on gonioscopy. A closed ACA on AS OCT imaging was defined by the presence of any contact between the iris and angle wall anterior to the scleral spur. Results After excluding eyes with poor image quality, a total of 423 right eyes were included in the analysis. A closed angle in at least 1 Quadrant was observed in 59% of the eyes by AS OCT and in 33% of the eyes by gonioscopy ( P Conclusions The highest rates of closed angles on gonioscopy and AS OCT images were observed in the superior Quadrant. Anterior segment OCT tended to detect more closed ACAs than gonioscopy, particularly in the superior and inferior Quadrants. Variations in the iris profile and level of iridoangle contact also may explain some of the differences seen between gonioscopy and AS OCT.
Bruce L Dalkin - One of the best experts on this subject based on the ideXlab platform.
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accuracy of digital rectal examination and transrectal ultrasonography in localizing prostate cancer
The Journal of Urology, 1994Co-Authors: Robert C Flanigan, William J Catalona, Jerome P Richie, Frederick R Ahmann, Mliss A Hudson, Peter T Scardino, Jean B Dekernion, Timothy L Ratliff, Louis R Kavoussi, Bruce L DalkinAbstract:AbstractNot all prostate cancers are sonographically hypoechoic or palpable on digital rectal examination, and suspicious areas on transrectal prostatic ultrasonography or digital rectal examination often are not cancer. We present Quadrant biopsy results from a multicenter prostate cancer screening study in which men were evaluated with prostate specific antigen (PSA) and digital rectal examination. If the PSA level was elevated (greater than 4.0 ng./ml., Hybritech Tandem assay) or digital rectal examination was suspicious Quadrant biopsies were performed. Biopsy specimens were labeled separately, and histological findings were correlated by Quadrant with the findings on ultrasonography and digital rectal examination. Of the 6,630 subjects enrolled into the study 16% were biopsied. Of 1,002 Quadrants that were suspicious on digital rectal examination 110 (11%) had cancer, while 308 of 418 Quadrants containing cancer (74%) were not suspicious on digital rectal examination. Of 855 Quadrants that were sonog...
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Accuracy of digital rectal examination and transrectal ultrasonography in localizing prostate cancer.
The Journal of urology, 1994Co-Authors: Robert C Flanigan, William J Catalona, Jerome P Richie, Frederick R Ahmann, Mliss A Hudson, Peter T Scardino, Jean B Dekernion, Timothy L Ratliff, Louis R Kavoussi, Bruce L DalkinAbstract:Not all prostate cancers are sonographically hypoechoic or palpable on digital rectal examination, and suspicious areas on transrectal prostatic ultrasonography or digital rectal examination often are not cancer. We present Quadrant biopsy results from a multicenter prostate cancer screening study in which men were evaluated with prostate specific antigen (PSA) and digital rectal examination. If the PSA level was elevated (greater than 4.0 ng./ml., Hybritech Tandem assay) or digital rectal examination was suspicious Quadrant biopsies were performed. Biopsy specimens were labeled separately, and histological findings were correlated by Quadrant with the findings on ultrasonography and digital rectal examination. Of the 6,630 subjects enrolled into the study 16% were biopsied. Of 1,002 Quadrants that were suspicious on digital rectal examination 110 (11%) had cancer, while 308 of 418 Quadrants containing cancer (74%) were not suspicious on digital rectal examination. Of 855 Quadrants that were sonographically suspicious 153 (18%) had cancer, while 282 of 435 Quadrants containing cancer (65%) were not sonographically suspicious. Of 225 patients with cancer 137 (61%) would have been missed if only the exact site of the palpable induration had been biopsied. Of 251 patients with cancer 131 (52%) would have been missed if only the exact site of the hypoechoic lesion had been biopsied. We conclude that digital rectal examination and transrectal ultrasonography have limited accuracy in identifying and localizing prostate cancer. Our study emphasizes the importance of obtaining systematic biopsies if the PSA level is elevated, even in the absence of digital rectal examination or ultrasound anomalies.
