Three-Dimensional Spectral-Domain Optical Coherence Tomography Data Analysis for Glaucoma Detection

Purpose: To develop a new three-dimensional (3D) spectral-domain optical coherence tomography (SD-OCT) data analysis method using a machine learning technique based on variable-size super pixel segmentation that efficiently utilizes full 3D dataset to improve the discrimination between early glaucomatous and healthy eyes. Methods: 192 eyes of 96 subjects (44 healthy, 59 glaucoma suspect and 89 glaucomatous eyes) were scanned with SD-OCT. Each SD-OCT cube dataset was first converted into 2D feature map based on retinal nerve fiber layer (RNFL) segmentation and then divided into various number of super pixels. Unlike the conventional super pixel having a fixed number of points, this newly developed variable-size super pixel is defined as a cluster of homogeneous adjacent pixels with variable size, shape and number. Features of super pixel map were extracted and used as inputs to machine classifier (LogitBoost adaptive boosting) to automatically identify diseased eyes. For discriminating performance assessment, area under the curve (AUC) of the receiver operating characteristics of the machine classifier outputs were compared with the conventional circumpapillary RNFL (cpRNFL) thickness measurements. Results: The super pixel analysis showed statistically significantly higher AUC than the cpRNFL (0.855 vs. 0.707, respectively, p = 0.031, Jackknife test) when glaucoma suspects were discriminated from healthy, while no significant difference was found when confirmed glaucoma eyes were discriminated from healthy eyes. Conclusions: A novel 3D OCT analysis technique performed at least as well as the cpRNFL in glaucoma discrimination and even better at glaucoma suspect discrimination. This new method has the potential to improve early detection of glaucomatous damage. © 2013 Xu et al

Effects of Age on Optical Coherence Tomography Measurements of Healthy Retinal Nerve Fiber Layer, Macula, and Optic Nerve Head

Purpose—To determine the effects of age on global and sectoral peripapillary retinal nerve fiber layer (RNFL), macular thicknesses and optic nerve head (ONH) parameters in healthy subjects using optical coherence tomography (OCT). Design—Retrospective, cross-sectional observational study. Participants—226 eyes from 124 healthy subjects were included. Methods—Healthy subjects were scanned using the Fast RNFL, Fast Macula, and Fast ONH scan patterns on a Stratus OCT. All global and sectoral RNFL and macular parameters and global ONH parameters were modeled in terms of age using linear mixed effects models. Normalized slopes were also calculated by dividing the slopes by the mean value of the OCT parameter for inter-parameter comparison. Main Outcome Measures—Slope of each OCT parameter across age. Results—All global and sectoral RNFL thickness parameters statistically significantly decreased with increasing age, except for the temporal quadrant and clock hours 8-10, which were not statistically different from a slope of zero. Highest absolute slopes were in the inferior and superior quadrant RNFL and clock hour 1 (superior nasal). Normalized slopes showed similar rate in all sectors except for the temporal clock hours (8-10). All macular thickness parameters statistically significantly decreased with increasing age, except for the central fovea sector, which had a slight positive slope that was not statistically significant. The nasal outer sector had the greatest absolute slope. Normalized macular slope in the outer ring was similar to the normalized slopes in the RNFL. Normalized inner ring had shallower slope than the outer ring with similar rate in all quadrants. Disc area remained nearly constant across the ages, but cup area increased and rim area decreased with age, both of which were statistically significant. Conclusions—Global and regional changes due to the effects of age on RNFL, macula and ONH OCT measurements should be considered when assessing eyes over time.National Institutes of Health (U.S.) (R01-EY13178-09)National Institutes of Health (U.S.) (R01-EY11289-23)National Institutes of Health (U.S.) (P30-EY008098

Reproducibility of in-vivo OCT measured three-dimensional human lamina cribrosa microarchitecture

Purpose: To determine the reproducibility of automated segmentation of the three-dimensional (3D) lamina cribrosa (LC) microarchitecture scanned in-vivo using optical coherence tomography (OCT). Methods: Thirty-nine eyes (8 healthy, 19 glaucoma suspects and 12 glaucoma) from 49 subjects were scanned twice using swept-source (SS-) OCT in a 3.5x3.5x3.64 mm (400x400x896 pixels) volume centered on the optic nerve head, with the focus readjusted after each scan. The LC was automatically segmented and analyzed for microarchitectural parameters, including pore diameter, pore diameter standard deviation (SD), pore aspect ratio, pore area, beam thickness, beam thickness SD, and beam thickness to pore diameter ratio. Reproducibility of the parameters was assessed by computing the imprecision of the parameters between the scans. Results: The automated segmentation demonstrated excellent reproducibility. All LC microarchitecture parameters had an imprecision of less or equal to 4.2%. There was little variability in imprecision with respect to diagnostic category, although the method tends to show higher imprecision amongst healthy subjects. Conclusion: The proposed automated segmentation of the LC demonstrated high reproducibility for 3D LC parameters. This segmentation analysis tool will be useful for in-vivo studies of the LC. © 2014 Wang et al

Training strategies and outcomes of ab interno trabeculectomy with the trabectome [version 2; referees: 2 approved]

Plasma-mediated ab interno trabeculectomy with the trabectome was first approved by the US Food and Drug Administration in 2004 for use in adult and pediatric glaucomas. Since then, increased clinical experience and updated outcome data have led to its expanded use, including a range of glaucomas and angle presentations, previously deemed to be relatively contraindicated. The main benefits are a high degree of safety, ease, and speed compared to traditional filtering surgery and tube shunts. The increasing burden of glaucoma and expanding life expectancy has resulted in demand for well-trained surgeons. In this article, we discuss the results of trabectome surgery in standard and nonstandard indications. We present training strategies of the surgical technique that include a pig eye model, and visualization exercises that can be performed before and at the conclusion of standard cataract surgery in patients who do not have glaucoma. We detail the mechanism of enhancing the conventional outflow pathway and describe methods of visualization and function testing

Training strategies and outcomes of ab interno trabeculectomy with the trabectome.

Plasma-mediated ab interno trabeculectomy with the trabectome was first approved by the US Food and Drug Administration in 2004 for use in adult and pediatric glaucomas. Since then, increased clinical experience and updated outcome data have led to its expanded use, including a range of glaucomas and angle presentations, previously deemed to be relatively contraindicated. The main benefits are a high degree of safety, ease, and speed compared to traditional filtering surgery and tube shunts. The increasing burden of glaucoma and expanding life expectancy has resulted in demand for well-trained surgeons. In this article, we discuss the results of trabectome surgery in standard and nonstandard indications. We present training strategies of the surgical technique that include a pig eye model, and visualization exercises that can be performed before and at the conclusion of standard cataract surgery in patients who do not have glaucoma. We detail the mechanism of enhancing the conventional outflow pathway and describe methods of visualization and function testing

Training strategies and outcomes of ab interno trabeculectomy with the trabectome.

Plasma-mediated ab interno trabeculectomy with the trabectome was first approved by the US Food and Drug Administration in 2004 for use in adult and pediatric glaucomas. Since then, increased clinical experience and updated outcome data have led to its expanded use, including a range of glaucomas and angle presentations, previously deemed to be relatively contraindicated. The main benefits are a high degree of safety, ease, and speed compared to traditional filtering surgery and tube shunts. The increasing burden of glaucoma and expanding life expectancy has resulted in demand for well-trained surgeons. In this article, we discuss the results of trabectome surgery in standard and nonstandard indications. We present training strategies of the surgical technique that include a pig eye model, and visualization exercises that can be performed before and at the conclusion of standard cataract surgery in patients who do not have glaucoma. We detail the mechanism of enhancing the conventional outflow pathway and describe methods of visualization and function testing