98 results on '"Yohannan J"'
Search Results
2. Emerson's Translations of Persian Poetry from German Sources
- Author
-
Yohannan, J. D.
- Published
- 1943
- Full Text
- View/download PDF
3. The Influence of Persian Poetry Upon Emerson's Work
- Author
-
Yohannan, J. D.
- Published
- 1943
- Full Text
- View/download PDF
4. Did Sir Richard Burton Translate Sadi's Gulistan?
- Author
-
Yohannan, J. D.
- Published
- 1950
5. A Wideband Conical Beam Cylindrical Dielectric Resonator Antenna
- Author
-
Ambattu, Praveen, Hamsakutty, V, Yohannan, J, Mathew, KT, Ambattu, Praveen, Hamsakutty, V, Yohannan, J, and Mathew, KT
- Abstract
The letter proposes a novel cylindrical dielectric resonator antenna (DRA) geometry with low radiation Q-value facilitating wide band operation with conical radiation patterns. The DRA is fed by a microstrip transmission line with a vertical strip that is attached to the DRA surface. At optimum dimensions and position of the vertical strip on the horizontal microstrip, the DRA exhibits an impedance bandwidth ( $vert {rm S}_{11}vert < - 10$ dB) of ${sim}35hbox{%}$ at the centre frequency of 3 GHz. Measured radiation patterns are conical in shape and are stable with moderate gain across the matching band.
- Published
- 2007
6. The Role of Abdominal Imaging in the Evaluation of Patients Following Robot-assisted Laparoscopic Radical Prostatectomy
- Author
-
Feng, T., primary, Yohannan, J., additional, and Allaf, M.E., additional
- Published
- 2009
- Full Text
- View/download PDF
7. Reply
- Author
-
Yohannan, J. D.
- Published
- 1943
- Full Text
- View/download PDF
8. Hexagonal dielectric resonator antenna for multi-frequency operation
- Author
-
Hamsakutty, V., primary, Praveen Kumar, A.V., additional, Yohannan, J., additional, and Mathew, K.T., additional
- Published
- 2006
- Full Text
- View/download PDF
9. A Rectangular Dielectric Resonator Band Stop Filter
- Author
-
Yohannan, J., primary, Hamsakutty, V., additional, Kumar, A.V.P., additional, Thomas, V., additional, Bindhu, G., additional, and Mathew, K.T., additional
- Published
- 2006
- Full Text
- View/download PDF
10. Half-split cylindrical dielectric resonator antenna for 2.4 GHz WLAN operation
- Author
-
Praveen Kumar, A.V., primary, Hamsakutty, V., additional, Yohannan, J., additional, and Mathew, K.T., additional
- Published
- 2006
- Full Text
- View/download PDF
11. Structural and microwave dielectric properties of Sr1-xBaxNb2O6ceramics at microwave frequencies
- Author
-
Yohannan, J., primary, Jacob, J., additional, Lonappan, A., additional, and Mathew, K.T., additional
- Published
- 2003
- Full Text
- View/download PDF
12. Microwave dielectric properties of strontium barium cerium niobate ferroelectric ceramics using cavity perturbation technique.
- Author
-
Yohannan, J., Kalappura, U.G., Vasudevan, K., and Mathew, K.T.
- Published
- 2010
13. Coupling medium for microwave medical imaging applications
- Author
-
Hamsakutty, V., primary, Lonappan, A., additional, Thomas, V., additional, Bindu, G., additional, Jacob, J., additional, Yohannan, J., additional, and Mathew, K.T., additional
- Published
- 2003
- Full Text
- View/download PDF
14. LOCALIZATION OF THE INVESTIGATION DOMAIN IN INVERSE PROFILING OF BURIED 2-D DIELECTRIC PIPELINES WITH CIRCULAR CROSS SECTION USING ELECTROMAGNETIC SCATTERED DATA.
- Author
-
Thomas, V., Yohannan, J., Lonappan, A., Bindu, G., and Mathew, K. T.
- Published
- 2006
15. MICROSTRIPLINE FED CYLINDRICAL DIELECTRIC RESONATOR ANTENNA WITH A COPLANAR PARASITIC STRIP.
- Author
-
Kumar, A. V. P., Hamsakutty, V., Yohannan, J., and Mathew, K. T.
- Published
- 2006
16. A NOVEL TECHNIQUE FOR LOCALIZING THE SCATTERER IN INVERSE PROFILING OF TWO DIMENSIONAL CIRCULARLY SYMMETRIC DIELECTRIC SCATTERERS USING DEGREE OF SYMMETRY AND NEURAL NETWORKS.
- Author
-
Thomas, V., Gopakumar, C., Yohannan, J., Lonappan, A., Bindu, G., Kumar, A. V.Praveen, Hamsakutty, V., and Mathew, K. T.
- Subjects
ARTIFICIAL neural networks ,MICROWAVE imaging ,IMAGING systems ,DIELECTRIC devices ,SCATTERING (Physics) ,ELECTRONICS - Abstract
A novel technique for localizing the scatterer in microwave imaging of two-dimensional circularly symmetric dielectric scatterers using degree of symmetry and neural networks is presented. The degree of symmetry for a transmitter position is computed as a function of the difference between the first half and the spatially reflected second half of the measured scattered field vector. A Probabilistic Neural Network (PNN) classifier is trained with the degree of symmetry vectors for the different object configurations. It classifies the degree of symmetry vector of the unknown circularly symmetric scatterer presented to it into one of the classes that indicate the radius and location of the centre of the scatterer. Thus the scatterer is localized in the imaging domain. This not only reduces the degrees of freedom in the inversion for the unknown object, thereby aiding the global convergence of the solution, but also results in a reduction in computation time. The technique has been tested on synthetic data and the results are promising. [ABSTRACT FROM AUTHOR]
- Published
- 2005
- Full Text
- View/download PDF
17. Structural and microwave dielectric properties of Sr[sub 1-x]Ba[sub x]Nb[sub 2]O[sub 6] ceramics at microwave frequencies.
- Author
-
Yohannan, J., Jacob, J., Lonappan, A., and Mathew, K.T.
- Subjects
- *
DIELECTRICS , *EXCITON theory , *CRYSTALS , *ELECTROMAGNETISM , *MICROWAVE circuits - Abstract
Microwave dielectric properties and crystal structure of Sr[sub 1-x]Ba[sub x]Nb[sub 2]O[sub 6] ceramics (x = 0·39, 0·45, 0·50, 0·55, 0·57, 0·60, 0·65) have been investigated. The microwave cavity perturbation technique was employed for the study of dielectric properties. Parameters such as complex permittivity and conductivity of strontium barium niobate ceramics were determined at the S band by measuring changes in the resonant frequencies and Q values of the cavity resulting from the introduction of the sample. The real part of the complex permittivity of all samples shows an increase with frequency, whereas the imaginary part of permittivity decreases as frequency increases. The effects of composition and sintering temperature on crystal structure and microstructure were studied by X-ray powder diffraction and scanning electron microscopy. Most compositions show preferred orientations along the c axis, as is evident from the relatively high intensity of (001) and (002) peaks. The microstructure contains ferroelectric domainlike structures with increasing barium content. [ABSTRACT FROM AUTHOR]
- Published
- 2003
- Full Text
- View/download PDF
18. Dielectric ring resonator band pass filter for 2.4 GHz WLAN frequencies.
- Author
-
Yohannan, J., Vasudevan, K., Mathew, K.T., and Abdulla, P.
- Published
- 2009
- Full Text
- View/download PDF
19. Structural and microwave dielectric properties of Sr1-xBaxNb2O6ceramics at microwave frequencies
- Author
-
Yohannan, J., Jacob, J., Lonappan, A., and Mathew, K.T.
- Abstract
Microwave dielectric properties and crystal structure of Sr1-xBaxNb2O6ceramics (x = 0·39, 0·45, 0·50, 0·55, 0·57, 0·60, 0·65) have been investigated. The microwave cavity perturbation technique was employed for the study of dielectric properties. Parameters such as complex permittivity and conductivity of strontium barium niobate ceramics were determined at the S band by measuring changes in the resonant frequencies and Q values of the cavity resulting from the introduction of the sample. The real part of the complex permittivity of all samples shows an increase with frequency, whereas the imaginary part of permittivity decreases as frequency increases. The effects of composition and sintering temperature on crystal structure and microstructure were studied by X-ray powder diffraction and scanning electron microscopy. Most compositions show preferred orientations along the c axis, as is evident from the relatively high intensity of (001) and (002) peaks. The microstructure contains ferroelectric domainlike structures with increasing barium content.
- Published
- 2003
- Full Text
- View/download PDF
20. Effect of heavy ion irradiation on the dielectric properties of selected barium sodium niobate ceramics
- Author
-
Yohannan, J., Nandakumar, K., and Kumar, R.
- Published
- 1999
- Full Text
- View/download PDF
21. Analysis of tyrosine phosphorylation-dependent interactions between stimulatory effector proteins and the B cell co-receptor CD22.
- Author
-
Yohannan, J, Wienands, J, Coggeshall, K M, and Justement, L B
- Abstract
The B cell-restricted transmembrane glycoprotein CD22 is rapidly phosphorylated on tyrosine in response to cross-linking of the B cell antigen receptor, thereby generating phosphotyrosine motifs in the cytoplasmic domain which recruit intracellular effector proteins that contain Src homology 2 domains. By virtue of its interaction with these effector proteins CD22 modulates signal transduction through the B cell antigen receptor. To define further the molecular mechanism by which CD22 mediates its co-receptor function, phosphopeptide mapping experiments were conducted to determine which of the six tyrosine residues in the cytoplasmic domain are involved in recruitment of the stimulatory effector proteins phospholipase Cgamma (PLCgamma), phosphoinositide 3-kinase (PI3K), Grb2, and Syk. The results obtained indicate that the protein tyrosine kinase Syk interacts with multiple CD22-derived phosphopeptides in both immunoprecipitation and reverse Far Western assays. In contrast, the Grb2.Sos complex was observed to bind exclusively to the fourth phosphotyrosine motif (Y828ENV) from CD22 and does so via a direct interaction based on Far Western and reverse Far Western blotting. Although both PLCgamma and PI3K were observed to bind to multiple phosphopeptides in precipitation experiments, subsequent studies using reverse Far Western blot analysis demonstrated that only the carboxyl-terminal phosphopeptide of CD22 (Y863VTL) binds directly to either one. This finding suggests that PLCgamma and PI3K may be recruited to CD22 either through a direct interaction with Tyr863 or indirectly through an association with one or more intermediate proteins.
- Published
- 1999
22. Microstripline fed circular sector dielectric resonator antenna
- Author
-
Kumar, A.V.P., primary, Yohannan, J., additional, Lonappan, A., additional, Bindu, G., additional, Vinu, T., additional, Hamsakkutty, V., additional, and Mathew, K.T., additional
- Full Text
- View/download PDF
23. Microwave ceramic resonator antenna for communication applications
- Author
-
Yohannan, J., primary, Kumar, A.V.P., additional, Thomas, V., additional, Hamsakkutty, V., additional, and Mathew, K.T., additional
- Full Text
- View/download PDF
24. Detection of dielectric contrast of breast tissues using confocal microwave technique.
- Author
-
Bindu, G., Abraham, S.J., Lonappan, A., Thomas, V., Yohannan, J., Aanandan, C.K., and Mathew, K.T.
- Published
- 2005
- Full Text
- View/download PDF
25. Microwave ceramic resonator antenna for communication applications.
- Author
-
Yohannan, J., Kumar, A.V.P., Thomas, V., Hamsakkutty, V., and Mathew, K.T.
- Published
- 2005
- Full Text
- View/download PDF
26. Microstripline fed circular sector dielectric resonator antenna.
- Author
-
Kumar, A.V.P., Yohannan, J., Lonappan, A., Bindu, G., Vinu, T., Hamsakkutty, V., and Mathew, K.T.
- Published
- 2005
- Full Text
- View/download PDF
27. Coaxial fed hexagonal dielectric resonator antenna.
- Author
-
Hamsakutty, V., Praveen Kumar, A.V., Yohannan, J., and Mathew, K.T.
- Published
- 2005
- Full Text
- View/download PDF
28. Detecting Glaucoma Worsening Using Optical Coherence Tomography Derived Visual Field Estimates.
- Author
-
Pham AT, Bradley C, Hou K, Herbert P, Unberath M, Ramulu PY, and Yohannan J
- Abstract
Objective: Multiple studies have attempted to generate visual field (VF) mean deviation (MD) estimates using cross-sectional optical coherence tomography (OCT) data. However, whether such models offer any value in detecting longitudinal VF progression is unclear. We address this by developing a machine learning (ML) model to convert OCT data to MD and assessing its ability to detect longitudinal worsening., Design: Retrospective, longitudinal study., Participants: A model dataset of 70,575 paired OCT/VFs to train an ML model converting OCT to VF-MD. A separate progression dataset of 4,044 eyes with ≥ 5 paired OCT/VFs to assess the ability of OCT-derived MD to detect worsening. Progression dataset eyes had two additional unpaired VFs (≥ 7 total) to establish a "ground truth" rate of progression defined by MD slope., Methods: We trained an ML model using paired VF/OCT data to estimate MD measurements for each OCT scan (OCT-MD). We used this ML model to generate longitudinal OCT-MD estimates for progression dataset eyes. We calculated MD slopes after substituting/supplementing VF-MD with OCT-MD and measured the ability to detect progression. We labeled true progressors using a ground truth MD slope <0.5 dB/year calculated from ≥ 7 VF-MD measurements. We compared the area under the curve (AUC) of MD slopes calculated using both VF-MD (with <7 measurements) and OCT-MD. Because we found OCT-MD substitution had a statistically inferior AUC to VF-MD, we simulated the effect of reducing OCT-MD mean absolute error (MAE) on the ability to detect worsening., Main Outcome Measures: AUC., Results: OCT-MD estimates had an MAE of 1.62 dB. AUC of MD slopes with partial OCT-MD substitution was significantly worse than the VF-MD slope. Supplementing VF-MD with OCT-MD also did not improve AUC, regardless of MAE. OCT-MD estimates needed an MAE ≤ 1.00 dB before AUC was statistically similar to VF-MD alone., Conclusion: ML models converting OCT data to VF-MD with error levels lower than published in prior work (MAE: 1.62 dB) were inferior to VF-MD data for detecting trend-based VF progression. Models converting OCT data to VF-MD must achieve better prediction errors (MAE ≤ 1 dB) to be clinically valuable at detecting VF worsening.
- Published
- 2024
- Full Text
- View/download PDF
29. Visual field testing in glaucoma using the Swedish Interactive Thresholding Algorithm (SITA).
- Author
-
Tan JCK, Yohannan J, Ramulu PY, Kalloniatis M, Crabb DP, Crowston J, and Phu J
- Abstract
The Swedish Interactive Thresholding Algorithm (SITA) is the main measurement acquisition algorithm used on the Humphrey Field Analyser, the most commonly used instrument for visual field (VF) assessment worldwide. We compare the sensitivity outputs and reliability parameters of the three currently available SITA algorithms-SITA Standard (SS), Fast (SF), and Faster (SFR), with a focus on the newly released SFR and the 24-2C test grid. SFR displays similar sensitivity outputs to SS and SF, but may not be interchangeable with SS in eyes with more severe VF loss. The reliability metric with the greatest impact on VF reliability is the level of false positives, although the recommended 15 % false positive cut off may be inappropriate as a threshold for judging whether a test is reliable and should be included for use in SFR. Finally, the 24-2C grid may be useful in flagging the presence of a clustered central VF defect, while the 10-2 grid can be used to more comprehensively characterize central field defects. We also discuss strategies to improve testing frequency in clinical practice., Competing Interests: Declaration of Competing Interest None., (Copyright © 2024 The Authors. Published by Elsevier Inc. All rights reserved.)
- Published
- 2024
- Full Text
- View/download PDF
30. Big data in visual field testing for glaucoma.
- Author
-
Pham AT, Pan AA, and Yohannan J
- Abstract
Recent technological advancements and the advent of ever-growing databases in health care have fueled the emergence of "big data" analytics. Big data has the potential to revolutionize health care, particularly ophthalmology, given the data-intensive nature of the medical specialty. As one of the leading causes of irreversible blindness worldwide, glaucoma is an ocular disease that receives significant interest for developing innovations in eye care. Among the most vital sources of data in glaucoma is visual field (VF) testing, which stands as a cornerstone for diagnosing and managing the disease. The expanding accessibility of large VF databases has led to a surge in studies investigating various applications of big data analytics in glaucoma. In this study, we review the use of big data for evaluating the reliability of VF tests, gaining insights into real-world clinical practices and outcomes, understanding new disease associations and risk factors, characterizing the patterns of VF loss, defining the structure-function relationship of glaucoma, enhancing early diagnosis or earlier detection of progression, informing clinical decisions, and improving clinical trials. Equally important, we discuss current challenges in big data analytics and future directions for improvement., Competing Interests: The authors declare that there are no conflicts of interests of this paper., (Copyright: © 2024 Taiwan J Ophthalmol.)
- Published
- 2024
- Full Text
- View/download PDF
31. Detecting Visual Field Worsening From Optic Nerve Head and Macular Optical Coherence Tomography Thickness Measurements.
- Author
-
Pham AT, Pan AA, Bradley C, Hou K, Herbert P, Johnson C, Wall M, and Yohannan J
- Subjects
- Humans, Female, Male, Middle Aged, Machine Learning, Aged, Nerve Fibers pathology, Area Under Curve, Macula Lutea diagnostic imaging, Macula Lutea pathology, Vision Disorders physiopathology, Vision Disorders diagnostic imaging, Vision Disorders diagnosis, Tomography, Optical Coherence methods, Optic Disk diagnostic imaging, Optic Disk pathology, Visual Fields physiology, Disease Progression, Glaucoma diagnostic imaging, Glaucoma physiopathology, Retinal Ganglion Cells pathology
- Abstract
Purpose: Compare the use of optic disc and macular optical coherence tomography measurements to predict glaucomatous visual field (VF) worsening., Methods: Machine learning and statistical models were trained on 924 eyes (924 patients) with circumpapillary retinal nerve fiber layer (cp-RNFL) or ganglion cell inner plexiform layer (GC-IPL) thickness measurements. The probability of 24-2 VF worsening was predicted using both trend-based and event-based progression definitions of VF worsening. Additionally, the cp-RNFL and GC-IPL predictions were combined to produce a combined prediction. A held-out test set of 617 eyes was used to calculate the area under the curve (AUC) to compare cp-RNFL, GC-IPL, and combined predictions., Results: The AUCs for cp-RNFL, GC-IPL, and combined predictions with the statistical and machine learning models were 0.72, 0.69, 0.73, and 0.78, 0.75, 0.81, respectively, when using trend-based analysis as ground truth. The differences in performance between the cp-RNFL, GC-IPL, and combined predictions were not statistically significant. AUCs were highest in glaucoma suspects using cp-RNFL predictions and highest in moderate/advanced glaucoma using GC-IPL predictions. The AUCs for the statistical and machine learning models were 0.63, 0.68, 0.69, and 0.72, 0.69, 0.73, respectively, when using event-based analysis. AUCs decreased with increasing disease severity for all predictions., Conclusions: cp-RNFL and GC-IPL similarly predicted VF worsening overall, but cp-RNFL performed best in early glaucoma stages and GC-IPL in later stages. Combining both did not enhance detection significantly., Translational Relevance: cp-RNFL best predicted trend-based 24-2 VF progression in early-stage disease, while GC-IPL best predicted progression in late-stage disease. Combining both features led to minimal improvement in predicting progression.
- Published
- 2024
- Full Text
- View/download PDF
32. The Impact of Social Vulnerability on Structural and Functional Glaucoma Severity, Worsening, and Variability.
- Author
-
Almidani L, Bradley C, Herbert P, Ramulu P, and Yohannan J
- Subjects
- Humans, Male, Female, Retrospective Studies, Middle Aged, Aged, Follow-Up Studies, Disease Progression, Visual Field Tests, Optic Disk pathology, Visual Fields physiology, Intraocular Pressure physiology, Tomography, Optical Coherence methods, Retinal Ganglion Cells pathology, Glaucoma physiopathology, Glaucoma diagnosis, Glaucoma complications, Severity of Illness Index, Nerve Fibers pathology
- Abstract
Purpose: To determine the associations between social vulnerability index (SVI) and baseline severity, worsening, and variability of glaucoma, as assessed by visual field (VF) and OCT., Design: Retrospective longitudinal cohort study., Participants: Adults with glaucoma or glaucoma suspect status in 1 or both eyes. Visual fields were derived from 7897 eyes from 4482 patients, while OCTs were derived from 6271 eyes from 3976 patients. All eyes had a minimum of 5 tests over follow-up using either the Humphrey Field Analyzer or the Cirrus HD-OCT., Methods: Social vulnerability index, which measures neighborhood-level environmental factors, was linked to patients' addresses at the census tract level. Rates of change in mean deviation (MD) and retinal nerve fiber layer (RNFL) thickness were computed using linear regression. The slope of the regression line was used to assess worsening, while the standard deviation of residuals was used as a measure of variability. Multivariable linear mixed-effects models were used to investigate the impact of SVI on baseline, worsening, and variability in both MD and RNFL. We further explored the interaction effect of mean intraocular pressure (IOP) and SVI on worsening in MD and RNFL., Main Outcome Measures: Glaucoma severity defined based on baseline MD and RNFL thickness. Worsening defined as MD and RNFL slope. Variability defined as the standard deviation of the residuals obtained from MD and RNFL slopes., Results: Increased (worse) SVI was significantly associated with worse baseline MD (β = -1.07 dB, 95% confidence interval [CI]: [-1.54, -0.60]), thicker baseline RNFL (β = 2.46 μm, 95% CI: [0.75, 4.17]), greater rates of RNFL loss (β = -0.12 μm, 95% CI: [-0.23, -0.02]), and greater VF variability (β = 0.16 dB, 95% CI: [0.07, 0.24]). Having worse SVI was associated with worse RNFL loss with increases in IOP (β
interaction = -0.07, 95% CI: [-0.12, -0.02])., Conclusions: Increased SVI score is associated with worse functional (VF) loss at baseline, higher rates of structural (OCT) worsening over time, higher VF variability, and a greater effect of IOP on RNFL loss. Further studies are needed to enhance our understanding of these relationships and establish their cause., Financial Disclosure(s): Proprietary or commercial disclosure may be found in the Footnotes and Disclosures at the end of this article., (Copyright © 2024 American Academy of Ophthalmology. Published by Elsevier Inc. All rights reserved.)- Published
- 2024
- Full Text
- View/download PDF
33. The Impact of Achieving Target Intraocular Pressure on Glaucomatous Retinal Nerve Fiber Layer Thinning in a Treated Clinical Population.
- Author
-
Pham AT, Bradley C, Hou K, Herbert P, Boland MV, Ramulu PY, and Yohannan J
- Subjects
- Humans, Male, Retrospective Studies, Female, Middle Aged, Aged, Antihypertensive Agents therapeutic use, Visual Field Tests, Optic Disk pathology, Optic Nerve Diseases physiopathology, Optic Nerve Diseases diagnosis, Optic Nerve Diseases drug therapy, Glaucoma physiopathology, Glaucoma diagnosis, Glaucoma drug therapy, Glaucoma, Open-Angle physiopathology, Glaucoma, Open-Angle diagnosis, Glaucoma, Open-Angle drug therapy, Intraocular Pressure physiology, Tomography, Optical Coherence methods, Retinal Ganglion Cells pathology, Nerve Fibers pathology, Visual Fields physiology, Tonometry, Ocular
- Abstract
Purpose: To estimate the effect of being below and above the clinician-set target intraocular pressure (IOP) on rates of glaucomatous retinal nerve fiber layer (RNFL) thinning in a treated real-world clinical population., Design: Retrospective cohort study., Methods: A total of 3256 eyes (1923 patients) with ≥5 reliable optical coherence tomography scans and 1 baseline visual field test were included. Linear mixed-effects modeling estimated the effects of the primary independent variables (mean target difference [measured IOP - target IOP] and mean IOP, mm Hg) on the primary dependent variable (RNFL slope, µm/y) while accounting for additional confounding variables (age, biological sex, race, baseline RNFL, baseline pachymetry, and disease severity). A spline term accounted for differential effects when above (target difference >0 mm Hg) and below (target difference ≤0 mm Hg) target pressure., Results: Eyes below and above target had significantly different mean RNFL slopes (-0.44 vs -0.71 µm/y, P < .001). Each 1 mm Hg increase above target had a 0.143 µm/y faster rate of RNFL thinning (P < .001). Separating by disease severity, suspect, mild, moderate, and advanced glaucoma had 0.135 (P = .002), 0.116 (P = .009), 0.203 (P = .02), and 0.65 (P = .22) µm/y faster rates of RNFL thinning per 1 mm Hg increase, respectively., Conclusions: Being above the clinician-set target pressure is associated with more rapid RNFL thinning in suspect, mild, and moderate glaucoma. Faster rates of thinning were also present in advanced glaucoma, but statistical significance was limited by the lower sample size of eyes above target and the optical coherence tomography floor effect., (Copyright © 2023 Elsevier Inc. All rights reserved.)
- Published
- 2024
- Full Text
- View/download PDF
34. Opportunities for Improving Glaucoma Clinical Trials via Deep Learning-Based Identification of Patients with Low Visual Field Variability.
- Author
-
Wang R, Bradley C, Herbert P, Hou K, Hager GD, Breininger K, Unberath M, Ramulu P, and Yohannan J
- Subjects
- Humans, Retrospective Studies, Female, Male, Clinical Trials as Topic, Glaucoma physiopathology, Glaucoma diagnosis, Visual Acuity physiology, Aged, Visual Field Tests methods, Middle Aged, Tomography, Optical Coherence methods, Deep Learning, Visual Fields physiology, Intraocular Pressure physiology
- Abstract
Purpose: Develop and evaluate the performance of a deep learning model (DLM) that forecasts eyes with low future visual field (VF) variability, and study the impact of using this DLM on sample size requirements for neuroprotective trials., Design: Retrospective cohort and simulation study., Methods: We included 1 eye per patient with baseline reliable VFs, OCT, clinical measures (demographics, intraocular pressure, and visual acuity), and 5 subsequent reliable VFs to forecast VF variability using DLMs and perform sample size estimates. We estimated sample size for 3 groups of eyes: all eyes (AE), low variability eyes (LVE: the subset of AE with a standard deviation of mean deviation [MD] slope residuals in the bottom 25th percentile), and DLM-predicted low variability eyes (DLPE: the subset of AE predicted to be low variability by the DLM). Deep learning models using only baseline VF/OCT/clinical data as input (DLM1), or also using a second VF (DLM2) were constructed to predict low VF variability (DLPE1 and DLPE2, respectively). Data were split 60/10/30 into train/val/test. Clinical trial simulations were performed only on the test set. We estimated the sample size necessary to detect treatment effects of 20% to 50% in MD slope with 80% power. Power was defined as the percentage of simulated clinical trials where the MD slope was significantly worse from the control. Clinical trials were simulated with visits every 3 months with a total of 10 visits., Results: A total of 2817 eyes were included in the analysis. Deep learning models 1 and 2 achieved an area under the receiver operating characteristic curve of 0.73 (95% confidence interval [CI]: 0.68, 0.76) and 0.82 (95% CI: 0.78, 0.85) in forecasting low VF variability. When compared with including AE, using DLPE1 and DLPE2 reduced sample size to achieve 80% power by 30% and 38% for 30% treatment effect, and 31% and 38% for 50% treatment effect., Conclusions: Deep learning models can forecast eyes with low VF variability using data from a single baseline clinical visit. This can reduce sample size requirements, and potentially reduce the burden of future glaucoma clinical trials., Financial Disclosure(s): Proprietary or commercial disclosure may be found in the Footnotes and Disclosures at the end of this article., (Copyright © 2024 American Academy of Ophthalmology. Published by Elsevier Inc. All rights reserved.)
- Published
- 2024
- Full Text
- View/download PDF
35. Assessment of linear regression of peripapillary optical coherence tomography retinal nerve fiber layer measurements to forecast glacuoma trajectory.
- Author
-
Bradley C, Hou K, Herbert P, Unberath M, Hager G, Boland MV, Ramulu P, and Yohannan J
- Subjects
- Humans, Linear Models, Retinal Ganglion Cells, Nerve Fibers, Intraocular Pressure, Tomography, Optical Coherence methods, Glaucoma diagnostic imaging
- Abstract
Linear regression of optical coherence tomography measurements of peripapillary retinal nerve fiber layer thickness is often used to detect glaucoma progression and forecast future disease course. However, current measurement frequencies suggest that clinicians often apply linear regression to a relatively small number of measurements (e.g., less than a handful). In this study, we estimate the accuracy of linear regression in predicting the next reliable measurement of average retinal nerve fiber layer thickness using Zeiss Cirrus optical coherence tomography measurements of average retinal nerve fiber layer thickness from a sample of 6,471 eyes with glaucoma or glaucoma-suspect status. Linear regression is compared to two null models: no glaucoma worsening, and worsening due to aging. Linear regression on the first M ≥ 2 measurements was significantly worse at predicting a reliable M+1st measurement for 2 ≤ M ≤ 6. This range was reduced to 2 ≤ M ≤ 5 when retinal nerve fiber layer thickness measurements were first "corrected" for scan quality. Simulations based on measurement frequencies in our sample-on average 393 ± 190 days between consecutive measurements-show that linear regression outperforms both null models when M ≥ 5 and the goal is to forecast moderate (75th percentile) worsening, and when M ≥ 3 for rapid (90th percentile) worsening. If linear regression is used to assess disease trajectory with a small number of measurements over short time periods (e.g., 1-2 years), as is often the case in clinical practice, the number of optical coherence tomography examinations needs to be increased., Competing Interests: The authors have declared that no competing interests exist., (Copyright: © 2024 Bradley et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.)
- Published
- 2024
- Full Text
- View/download PDF
36. Deep learning-based identification of eyes at risk for glaucoma surgery.
- Author
-
Wang R, Bradley C, Herbert P, Hou K, Ramulu P, Breininger K, Unberath M, and Yohannan J
- Subjects
- Adult, Humans, Retrospective Studies, Retina, Ophthalmology, Deep Learning, Glaucoma surgery, Trabeculectomy
- Abstract
To develop and evaluate the performance of a deep learning model (DLM) that predicts eyes at high risk of surgical intervention for uncontrolled glaucoma based on multimodal data from an initial ophthalmology visit. Longitudinal, observational, retrospective study. 4898 unique eyes from 4038 adult glaucoma or glaucoma-suspect patients who underwent surgery for uncontrolled glaucoma (trabeculectomy, tube shunt, xen, or diode surgery) between 2013 and 2021, or did not undergo glaucoma surgery but had 3 or more ophthalmology visits. We constructed a DLM to predict the occurrence of glaucoma surgery within various time horizons from a baseline visit. Model inputs included spatially oriented visual field (VF) and optical coherence tomography (OCT) data as well as clinical and demographic features. Separate DLMs with the same architecture were trained to predict the occurrence of surgery within 3 months, within 3-6 months, within 6 months-1 year, within 1-2 years, within 2-3 years, within 3-4 years, and within 4-5 years from the baseline visit. Included eyes were randomly split into 60%, 20%, and 20% for training, validation, and testing. DLM performance was measured using area under the receiver operating characteristic curve (AUC) and precision-recall curve (PRC). Shapley additive explanations (SHAP) were utilized to assess the importance of different features. Model prediction of surgery for uncontrolled glaucoma within 3 months had the best AUC of 0.92 (95% CI 0.88, 0.96). DLMs achieved clinically useful AUC values (> 0.8) for all models that predicted the occurrence of surgery within 3 years. According to SHAP analysis, all 7 models placed intraocular pressure (IOP) within the five most important features in predicting the occurrence of glaucoma surgery. Mean deviation (MD) and average retinal nerve fiber layer (RNFL) thickness were listed among the top 5 most important features by 6 of the 7 models. DLMs can successfully identify eyes requiring surgery for uncontrolled glaucoma within specific time horizons. Predictive performance decreases as the time horizon for forecasting surgery increases. Implementing prediction models in a clinical setting may help identify patients that should be referred to a glaucoma specialist for surgical evaluation., (© 2024. The Author(s).)
- Published
- 2024
- Full Text
- View/download PDF
37. Prediction of MIGS outcomes on second eyes using first eyes' response.
- Author
-
Dickinson A, Leidy L, Nusair O, Rachapudi S, Valenzuela T, Ramulu P, Mihailovic A, Yohannan J, Kaleem M, Johnson TV, and An J
- Subjects
- Humans, Retrospective Studies, Intraocular Pressure, Eye, Treatment Outcome, Glaucoma surgery, Cataract Extraction
- Abstract
To evaluate how well outcomes following cataract extraction and microinvasive glaucoma surgery in one eye predict outcomes in sequential second eye. Retrospective study of 78 patients who underwent cataract extraction and microinvasive glaucoma surgery in both eyes. Linear regressions using Pearson correlation coefficients were used to evaluate correlations in intraocular pressure and glaucoma medication change between eyes. Multivariable logistic regression models were used to evaluate the associations between first-eye variables and the likelihood of second-eye surgical success at 6 months. Surgical success was defined as meeting target intraocular pressure without additional medications compared to baseline or secondary surgical interventions. Baseline ocular characteristics were comparable between fellow eyes, with the majority having mild glaucoma. Intraocular pressure changes between fellow eyes at 6 months were modestly correlated between eyes (R = 0.48; P < .001). Changes in glaucoma medications were strongly correlated between eyes at all time points, and month 6 demonstrated the most significant correlation (R = 0.80; P < .001). First and second eye cohorts achieved 82% and 83% surgical success. Multivariate analysis for predictive factors of successful second eye surgery showed patients with successful first eye surgery at 6 months were significantly more likely to have successful second eye surgery (odds ratio, 20.67; P < .001). Reductions in intraocular pressure and glaucoma medications at 6 months following surgery in first eyes are correlated to second eye reductions. Successful surgical outcomes at 6 months following first eye surgeries are strongly associated with successful sequential second eye outcomes., (Copyright © 2023 the Author(s). Published by Wolters Kluwer Health, Inc.)
- Published
- 2023
- Full Text
- View/download PDF
38. Short-Term Outcomes of Hydrus Microstent With and Without Additional Canaloplasty During Cataract Surgery.
- Author
-
Dickinson A, Leidy L, Nusair O, Mihailovic A, Ramulu P, Yohannan J, Johnson TV 3rd, Kaleem M, Rachapudi S, and An J
- Subjects
- Humans, Intraocular Pressure, Retrospective Studies, Glaucoma, Open-Angle complications, Glaucoma, Open-Angle surgery, Phacoemulsification methods, Limbus Corneae surgery, Cataract complications
- Abstract
Prcis: Compared with phacoemulsification and microstent alone, we observed that phacoemulsification with combined microstent and canaloplasty resulted in a significantly greater reduction in glaucoma medications while maintaining similar rates of intraocular pressure reduction and low complications., Purpose: The purpose of this study was to compare the outcomes of phacoemulsification combined with Hydrus Microstent (Alcon Inc.) implantation alone or in combination with canaloplasty (OMNI Surgical System, Sight Sciences Inc.)., Materials and Methods: Retrospective study of mild-to-moderate primary open angle glaucoma patients who underwent phacoemulsification with microstent alone (42 eyes of 42 patients) or in combination with canaloplasty (canaloplasty-microstent, 32 eyes of 32 patients). The mean number of ocular hypotensive medications and intraocular pressure were assessed preoperatively and postoperatively at 1 week and at 1, 3, and 6 months. Complications and secondary surgical interventions were recorded. Outcomes measures included the percentage of unmedicated eyes and surgical success at 6 months. Surgical success was defined as reaching the target intraocular pressure without medications or secondary surgical interventions., Results: Mean intraocular pressure at 6 months was 14.1±3.5 mm Hg (13% reduction) after microstent alone and 13.6±3.1 mm Hg (17% reduction) after canaloplasty-microstent. Mean medications at 6 months were 0.57±0.9 (67% reduction) after microstent alone and 0.16±0.4 (88% reduction) after canaloplasty-microstent ( P< 0.05). At 6 months, 64.3% of microstent alone and 87.3% of canaloplasty-microstent were off all medications ( P =0.02). Success probabilities at 6 months were 44.5% for microstent alone and 70.0% for canaloplasty-microstent ( P =0.04). No secondary surgical interventions occurred in either group., Conclusions: Microstent combined with canaloplasty resulted in a significantly higher rate of medication-free status compared with microstent alone through 6 months., Competing Interests: Disclosure: J.A. reports consulting fees from Alcon and Sight Sciences. J.Y. and P.R. report consulting fees from Alcon. T.V.J. reports research support from Alcon. M.K. reports consulting fees from Sight Sciences. The remaining authors declare no conflict of interest., (Copyright © 2023 Wolters Kluwer Health, Inc. All rights reserved.)
- Published
- 2023
- Full Text
- View/download PDF
39. Forecasting Risk of Future Rapid Glaucoma Worsening Using Early Visual Field, OCT, and Clinical Data.
- Author
-
Herbert P, Hou K, Bradley C, Hager G, Boland MV, Ramulu P, Unberath M, and Yohannan J
- Subjects
- Humans, Visual Fields, Visual Field Tests methods, Tomography, Optical Coherence methods, Retrospective Studies, Volatile Organic Compounds, Glaucoma
- Abstract
Purpose: To assess whether we can forecast future rapid visual field (VF) worsening using deep learning models (DLMs) trained on early VF, OCT, and clinical data., Design: A retrospective cohort study., Subjects: In total, 4536 eyes from 2962 patients. Overall, 263 (5.80%) eyes underwent rapid VF worsening (mean deviation slope less than -1 dB/year across all VFs)., Methods: We included eyes that met the following criteria: (1) followed for glaucoma or suspect status; (2) had at least 5 longitudinal reliable VFs (VF
1 , VF2 , VF3 , VF4 , and VF5 ); and (3) had 1 reliable baseline OCT scan (OCT1 ) and 1 set of baseline clinical measurements (clinical1 ) at the time of VF1 . We designed a DLM to forecast future rapid VF worsening. The input consisted of spatially oriented total deviation values from VF1 (including or not including VF2 and VF3 in some models) and retinal nerve fiber layer thickness values from the baseline OCT. We passed this VF/OCT stack into a vision transformer feature extractor, the output of which was concatenated with baseline clinical data before putting it through a linear classifier to predict the eye's risk of rapid VF worsening across the 5 VFs. We compared the performance of models with differing inputs by computing area under the curve (AUC) in the test set. Specifically, we trained models with the following inputs: (1) model V: VF1 ; (2) VC: VF1 + Clinical1 ; (3) VO: VF1 + OCT1 ; (4) VOC: VF1 + Clinical1 + OCT1 ; (5) V2 : VF1 + VF2 ; (6) V2 OC: VF1 + VF2 + Clinical1 + OCT1 ; (7) V3 : VF1 + VF2 + VF3 ; and (8) V3 OC: VF1 + VF2 + VF3 + Clinical1 + OCT1 ., Main Outcome Measures: The AUC of DLMs when forecasting rapidly worsening eyes., Results: Model V3 OC best forecasted rapid worsening with an AUC (95% confidence interval [CI]) of 0.87 (0.77-0.97). Remaining models in descending order of performance and their respective AUC (95% CI) were as follows: (1) model V3 (0.84 [0.74-0.95]), (2) model V2 OC (0.81 [0.70-0.92]), (3) model V2 (0.81 [0.70-0.82]), (4) model VOC (0.77 [0.65-0.88]), (5) model VO (0.75 [0.64-0.88]), (6) model VC (0.75 [0.63-0.87]), and (7) model V (0.74 [0.62-0.86])., Conclusions: Deep learning models can forecast future rapid glaucoma worsening with modest to high performance when trained using data from early in the disease course. Including baseline data from multiple modalities and subsequent visits improves performance beyond using VF data alone., Financial Disclosure(s): Proprietary or commercial disclosure may be found in the Footnotes and Disclosures at the end of this article., (Copyright © 2023 American Academy of Ophthalmology. Published by Elsevier Inc. All rights reserved.)- Published
- 2023
- Full Text
- View/download PDF
40. Predicting Visual Field Worsening with Longitudinal OCT Data Using a Gated Transformer Network.
- Author
-
Hou K, Bradley C, Herbert P, Johnson C, Wall M, Ramulu PY, Unberath M, and Yohannan J
- Subjects
- Humans, Retrospective Studies, Bayes Theorem, Tomography, Optical Coherence, Longitudinal Studies, Vision Disorders diagnosis, Visual Field Tests methods, Intraocular Pressure, Disease Progression, Visual Fields, Glaucoma diagnosis
- Abstract
Purpose: To identify visual field (VF) worsening from longitudinal OCT data using a gated transformer network (GTN) and to examine how GTN performance varies for different definitions of VF worsening and different stages of glaucoma severity at baseline., Design: Retrospective longitudinal cohort study., Participants: A total of 4211 eyes (2666 patients) followed up at the Johns Hopkins Wilmer Eye Institute with at least 5 reliable VF results and 1 reliable OCT scan within 1 year of each reliable VF test., Methods: For each eye, we used 3 trend-based methods (mean deviation [MD] slope, VF index slope, and pointwise linear regression) and 3 event-based methods (Guided Progression Analysis, Collaborative Initial Glaucoma Treatment Study scoring system, and Advanced Glaucoma Intervention Study [AGIS] scoring system) to define VF worsening. Additionally, we developed a "majority of 6" algorithm (M6) that classifies an eye as worsening if 4 or more of the 6 aforementioned methods classified the eye as worsening. Using these 7 reference standards for VF worsening, we trained 7 GTNs that accept a series of at least 5 as input OCT scans and provide as output a probability of VF worsening. Gated transformer network performance was compared with non-deep learning models with the same serial OCT input from previous studies-linear mixed-effects models (MEMs) and naive Bayes classifiers (NBCs)-using the same training sets and reference standards as for the GTN., Main Outcome Measures: Area under the receiver operating characteristic curve (AUC)., Results: The M6 labeled 63 eyes (1.50%) as worsening. The GTN achieved an AUC of 0.97 (95% confidence interval, 0.88-1.00) when trained with M6. Gated transformer networks trained and optimized with the other 6 reference standards showed an AUC ranging from 0.78 (MD slope) to 0.89 (AGIS). The 7 GTNs outperformed all 7 MEMs and all 7 NBCs accordingly. Gated transformer network performance was worse for eyes with more severe glaucoma at baseline., Conclusions: Gated transformer network models trained with OCT data may be used to identify VF worsening. After further validation, implementing such models in clinical practice may allow us to track functional worsening of glaucoma with less onerous structural testing., Financial Disclosure(s): Proprietary or commercial disclosure may be found after the references., (Copyright © 2023 American Academy of Ophthalmology. All rights reserved.)
- Published
- 2023
- Full Text
- View/download PDF
41. Comparing the Accuracy of Peripapillary OCT Scans and Visual Fields to Detect Glaucoma Worsening.
- Author
-
Bradley C, Herbert P, Hou K, Unberath M, Ramulu P, and Yohannan J
- Subjects
- Adult, Humans, Tomography, Optical Coherence methods, Retinal Ganglion Cells, Nerve Fibers, Visual Field Tests methods, Intraocular Pressure, Visual Fields, Glaucoma diagnosis
- Abstract
Purpose: To compare the accuracy of detecting moderate and rapid rates of glaucoma worsening over a 2-year period with different numbers of OCT scans and visual field (VF) tests in a large sample of glaucoma and glaucoma suspect eyes., Design: Descriptive and simulation study., Participants: The OCT sample comprised 12 150 eyes from 7392 adults with glaucoma or glaucoma suspect status followed up at the Wilmer Eye Institute from 2013 through 2021. The VF sample comprised 20 583 eyes from 10 958 adults from the same database. All eyes had undergone at least 5 measurements over follow-up from the Zeiss Cirrus OCT or Humphrey Field Analyzer., Methods: Within-eye rates of change in retinal nerve fiber layer (RNFL) thickness and mean deviation (MD) were measured using linear regression. For each measured rate, simulated measurements of RNFL thickness and MD were generated using the distributions of residuals. Simulated rates of change for different numbers of OCT scans and VF tests over a 2-year period were used to estimate the accuracy of detecting moderate (75th percentile) and rapid (90th percentile) worsening for OCT and VF. Accuracy was defined as the percentage of simulated eyes in which the true rate of worsening (the rate without measurement error) was at or less than a criterion rate (e.g., 75th or 90th percentile)., Main Outcome Measures: The accuracy of diagnosing moderate and rapid rates of glaucoma worsening for different numbers of OCT scans and VF tests over a 2-year period., Results: Accuracy was less than 50% for both OCT and VF when diagnosing worsening after a 2-year period. OCT accuracy was 5 to 10 percentage points higher than VF accuracy at detecting moderate worsening and 10 to 15 percentage points higher for rapid worsening. Accuracy increased by more than 17 percentage points when using both OCT and VF to detect worsening, that is, when relying on either OCT or VF to be accurate., Conclusions: More frequent OCT scans and VF tests are needed to improve the accuracy of diagnosing glaucoma worsening. Accuracy greatly increases when relying on both OCT and VF to detect worsening., Financial Disclosure(s): The author(s) have no proprietary or commercial interest in any materials discussed in this article., (Copyright © 2023 American Academy of Ophthalmology. Published by Elsevier Inc. All rights reserved.)
- Published
- 2023
- Full Text
- View/download PDF
42. A deep learning model incorporating spatial and temporal information successfully detects visual field worsening using a consensus based approach.
- Author
-
Sabharwal J, Hou K, Herbert P, Bradley C, Johnson CA, Wall M, Ramulu PY, Unberath M, and Yohannan J
- Subjects
- Female, Humans, Middle Aged, Visual Fields, Consensus, Vision Disorders diagnosis, Visual Field Tests methods, Intraocular Pressure, Retrospective Studies, Disease Progression, Deep Learning, Glaucoma diagnosis
- Abstract
Glaucoma is a leading cause of irreversible blindness, and its worsening is most often monitored with visual field (VF) testing. Deep learning models (DLM) may help identify VF worsening consistently and reproducibly. In this study, we developed and investigated the performance of a DLM on a large population of glaucoma patients. We included 5099 patients (8705 eyes) seen at one institute from June 1990 to June 2020 that had VF testing as well as clinician assessment of VF worsening. Since there is no gold standard to identify VF worsening, we used a consensus of six commonly used algorithmic methods which include global regressions as well as point-wise change in the VFs. We used the consensus decision as a reference standard to train/test the DLM and evaluate clinician performance. 80%, 10%, and 10% of patients were included in training, validation, and test sets, respectively. Of the 873 eyes in the test set, 309 [60.6%] were from females and the median age was 62.4; (IQR 54.8-68.9). The DLM achieved an AUC of 0.94 (95% CI 0.93-0.99). Even after removing the 6 most recent VFs, providing fewer data points to the model, the DLM successfully identified worsening with an AUC of 0.78 (95% CI 0.72-0.84). Clinician assessment of worsening (based on documentation from the health record at the time of the final VF in each eye) had an AUC of 0.64 (95% CI 0.63-0.66). Both the DLM and clinician performed worse when the initial disease was more severe. This data shows that a DLM trained on a consensus of methods to define worsening successfully identified VF worsening and could help guide clinicians during routine clinical care., (© 2023. The Author(s).)
- Published
- 2023
- Full Text
- View/download PDF
43. Evidence-Based Guidelines for the Number of Peripapillary OCT Scans Needed to Detect Glaucoma Worsening.
- Author
-
Bradley C, Hou K, Herbert P, Unberath M, Boland MV, Ramulu P, and Yohannan J
- Subjects
- Adult, Humans, Tomography, Optical Coherence methods, Intraocular Pressure, Visual Fields, Retinal Ganglion Cells, Nerve Fibers, Optic Disk, Optic Nerve Diseases diagnosis, Glaucoma diagnosis, Ocular Hypertension
- Abstract
Purpose: To estimate the number of OCT scans necessary to detect moderate and rapid rates of retinal nerve fiber layer (RNFL) thickness worsening at different levels of accuracy using a large sample of glaucoma and glaucoma-suspect eyes., Design: Descriptive and simulation study., Participants: Twelve thousand one hundred fifty eyes from 7392 adult patients with glaucoma or glaucoma-suspect status followed up at the Wilmer Eye Institute from 2013 through 2021. All eyes had at least 5 measurements of RNFL thickness on the Cirrus OCT (Carl Zeiss Meditec) with signal strength of 6 or more., Methods: Rates of RNFL worsening for average RNFL thickness and for the 4 quadrants were measured using linear regression. Simulations were used to estimate the accuracy of detecting worsening-defined as the percentage of patients in whom the true rate of RNFL worsening was at or less than different criterion rates of worsening when the OCT-measured rate was also at or less than these criterion rates-for two different measurement strategies: evenly spaced (equal time intervals between measurements) and clustered (approximately half the measurements at each end point of the period)., Main Outcome Measures: The 75th percentile (moderate) and 90th percentile (rapid) rates of RNFL worsening for average RNFL thickness and the accuracy of diagnosing worsening at these moderate and rapid rates., Results: The 75th and 90th percentile rates of worsening for average RNFL thickness were -1.09 μm/year and -2.35 μm/year, respectively. Simulations showed that, for the average measurement frequency in our sample of approximately 3 OCT scans over a 2-year period, moderate and rapid RNFL worsening were diagnosed accurately only 47% and 40% of the time, respectively. Estimates for the number of OCT scans needed to achieve a range of accuracy levels are provided. For example, 60% accuracy requires 7 measurements to detect both moderate and rapid worsening within a 2-year period if the more efficient clustered measurement strategy is used., Conclusions: To diagnose RNFL worsening more accurately, the number of OCT scans must be increased compared with current clinical practice. A clustered measurement strategy reduces the number of scans required compared with evenly spacing measurements., (Copyright © 2022 American Academy of Ophthalmology. Published by Elsevier Inc. All rights reserved.)
- Published
- 2023
- Full Text
- View/download PDF
44. Effectiveness of Netarsudil versus Brimonidine in Eyes already Being Treated with Glaucoma Medications at a Single Academic Tertiary Care Practice: A Comparative Study.
- Author
-
Pham AT, Bradley C, Casey C, Jampel HD, Ramulu PY, and Yohannan J
- Abstract
Background: Rho kinase inhibitors, such as netarsudil, are a relatively new class of medications recently introduced into the market for the treatment of glaucoma, the leading cause of irreversible blindness in the world. Previous clinical trials have studied netarsudil's efficacy when used as a first- or second-line agent but limited studies have investigated its effectiveness in the real world where it is more commonly used as a third, fourth, or fifth agent in combination with other topical medications. Equally important, prior studies have not compared its effectiveness to its peer medications in these settings., Objective: To compare intraocular pressure (IOP) lowering after initiation of netarsudil or brimonidine therapy in patients with glaucoma using >2 medications for IOP management., Methods: A chart review of 369 eyes from 279 patients followed at a single academic tertiary practice was performed with an institutional review board waiver of consent to compare IOP lowering after prescription of netarsudil (n = 176) versus brimonidine (n = 193) as a third, fourth, or fifth IOP-lowering agent. Patients were identified by querying the electronic medical record for those with a glaucoma-related diagnosis who were prescribed either medication. Five sequential IOP measurements were obtained to determine the mean change in IOP before and after treatment (ΔIOP = mean IOP
4,5 - mean IOP1,2,3 ). A multilevel linear mixed-effects model assessed the influence of medication (independent variable) on ΔIOP (dependent variable). Additional independent variables of interest included the number of glaucoma medications at baseline, age, sex, glaucoma type and severity, race, and pretreatment IOP. Bootstrap analysis was performed to remove sampling bias and confirm mixed-effects model findings. Kaplan-Meier survival analysis evaluated the probability of requiring additional intervention within 3 years following the date of medication prescription., Results: The unadjusted mean (SD) ΔIOP for netarsudil and brimonidine was -2.20 (4.11) mm Hg and -2.21 (3.25) mm Hg, respectively ( P = 0.484). The adjusted linear mixed-effects models and bootstrap analysis demonstrated that there was no statistical difference in IOP-lowering effectiveness between the medications. Netarsudil and brimonidine failed to adequately control IOP at similar rates with 42% and 47% probabilities of survival respectively by the 3-year follow-up ( P = 0.520)., Conclusions: When escalating pharmacologic therapy, the IOP-lowering effect of netarsudil appeared to be similar to that produced by brimonidine. ( Curr Ther Res Clin Exp . 2023; 84:XXX-XXX)., Competing Interests: J. Yohannan is a consultant for Abbvie and Ivastis and receives research support from Genentech. The authors have indicated that they have no other conflicts of interest regarding the content of this article., (© 2022 The Author(s).)- Published
- 2022
- Full Text
- View/download PDF
45. Improving Visual Field Forecasting by Correcting for the Effects of Poor Visual Field Reliability.
- Author
-
Villasana GA, Bradley C, Elze T, Myers JS, Pasquale L, De Moraes CG, Wellik S, Boland MV, Ramulu P, Hager G, Unberath M, and Yohannan J
- Subjects
- Humans, Regression Analysis, Reproducibility of Results, Visual Field Tests methods, Glaucoma, Visual Fields
- Abstract
Purpose: The purpose of this study was to accurately forecast future reliable visual field (VF) mean deviation (MD) values by correcting for poor reliability., Methods: Four linear regression techniques (standard, unfiltered, corrected, and weighted) were fit to VF data from 5939 eyes with a final reliable VF. For each eye, all VFs, except the final one, were used to fit the models. Then, the difference between the final VF MD value and each model's estimate for the final VF MD value was used to calculate model error. We aggregated the error for each model across all eyes to compare model performance. The results were further broken down into eye-level reliability subgroups to track performance as reliability levels fluctuate., Results: The standard method, used in the Humphrey Field Analyzer (HFA), was the worst performing model with an average residual that was 0.69 dB higher than the average from the unfiltered method, and 0.79 dB higher than that of the weighted and corrected methods. The weighted method was the best performing model, beating the standard model by as much as 1.75 dB in the 40% to 50% eye-level reliability subgroup. However, its average 95% prediction interval was relatively large at 7.67 dB., Conclusions: Including all VFs in the trend estimation has more predictive power for future reliable VFs than excluding unreliable VFs. Correcting for VF reliability further improves model accuracy., Translational Relevance: The VF correction methods described in this paper may allow clinicians to catch VF worsening at an earlier stage.
- Published
- 2022
- Full Text
- View/download PDF
46. Reduced Intraocular Pressure Variability after Gonioscopy-Assisted Transluminal Trabeculotomy Procedure.
- Author
-
Geyman LS, Pitha I, and Yohannan J
- Subjects
- Gonioscopy, Humans, Intraocular Pressure, Glaucoma, Open-Angle surgery, Ocular Hypotension, Trabeculectomy methods
- Published
- 2022
- Full Text
- View/download PDF
47. Differences in visual field loss pattern when transitioning from SITA standard to SITA faster.
- Author
-
Le CT, Fiksel J, Ramulu P, and Yohannan J
- Subjects
- Algorithms, Humans, Sweden, Vision Disorders diagnosis, Visual Field Tests, Glaucoma diagnosis, Visual Fields
- Abstract
Swedish Interactive Threshold Algorithm (SITA) Faster is the most recent and fastest testing algorithm for the evaluation of Humphrey visual fields (VF). However, existing evidence suggests that there are some differences in global measures of VF loss in eyes transitioning from SITA Standard to the newer SITA Faster. These differences may be relevant, especially in glaucoma, where VF changes over time influence clinical decisions around treatment. Furthermore, characterization of differences in localizable VF loss patterns between algorithms, rather than global summary measures, can be important for clinician interpretation when transitioning testing strategies. In this study, we determined the effect of transitioning from SITA Standard to SITA Faster on VF loss patterns in glaucomatous eyes undergoing longitudinal VF testing in a real-world clinical setting. Archetypal analysis was used to derive composition weights of 16 clinically relevant VF patterns (i.e., archetypes (AT)) from patient VFs. We found switching from SITA Standard to SITA Faster was associated with less preservation of VF loss (i.e., abnormal AT 2-4, 6-9, 11, 13, 14) relative to successive SITA Standard exams (P value < 0.01) and was associated with relatively greater preservation of AT 1, the normal VF (P value < 0.01). Eyes that transition from SITA Standard to SITA Faster in a real-world clinical setting have an increased likelihood of preserving patterns reflecting a normal VF and lower tendency to preserve patterns reflecting abnormal VF as compared to consecutive SITA Standard exams in the same eye., (© 2022. The Author(s).)
- Published
- 2022
- Full Text
- View/download PDF
48. Cognitive behavioral treatments for children and adolescents exposed to traumatic events: A meta-analysis examining variables moderating treatment outcomes.
- Author
-
Yohannan J, Carlson JS, and Volker MA
- Subjects
- Adolescent, Child, Cognition, Humans, Treatment Outcome, Cognitive Behavioral Therapy methods, Problem Behavior, Stress Disorders, Post-Traumatic psychology, Stress Disorders, Post-Traumatic therapy
- Abstract
Due to the negative impact of trauma exposure, effective treatments are necessary to prevent and improve negative trauma-related outcomes. Cognitive behavioral therapy (CBT) is considered an efficacious treatment for children and adolescents exposed to traumatic events. Despite the various meta-analyses that have examined trauma treatments, there is a paucity of research on the moderating variables that may impact treatment outcomes. This meta-analytic CBT study addressed those limitations by examining the moderating effects of treatment components on outcomes. A search identified 94 CBT studies with 97 relevant effect sizes for children and adolescents exposed to traumatic events. Consistent with prior meta-analytic studies, CBT was shown to be effective for trauma-exposed youth. CBT subtreatments did not produce significantly different results from one another. Moderators shown to significantly impact CBT treatment outcomes for posttraumatic stress symptom were trauma type, Q = 24.09, p = .004, ds = -0.22 to -1.42, and gender, Q = 10.68, p = .005, ds = -0.53 to -1.36, whereas moderators shown to impact treatment outcomes for depression were study design, Q = 10.95, p = .004, ds = -0.26 to -0.50, and treatment setting, Q = 10.98, p = .004, ds = -0.31 to -0.56. The implications of these findings for research and practice are discussed., (© 2021 International Society for Traumatic Stress Studies.)
- Published
- 2022
- Full Text
- View/download PDF
49. Reliability of Several Glaucoma Tests in Patients With Boston Type 1 Keratoprosthesis.
- Author
-
Akpek EK, Karakus S, Yohannan J, Jabbour S, Sotimehin AE, Li G, and Ramulu PY
- Subjects
- Aged, Female, Follow-Up Studies, Glaucoma diagnosis, Glaucoma physiopathology, Humans, Keratoplasty, Penetrating methods, Male, Middle Aged, Prospective Studies, Prosthesis Design, Reproducibility of Results, Tomography, Optical Coherence methods, Artificial Organs, Cornea surgery, Glaucoma surgery, Intraocular Pressure physiology, Prostheses and Implants, Prosthesis Implantation methods, Visual Acuity
- Abstract
Purpose: Managing glaucoma after Boston type 1 keratoprosthesis (KPro) surgery remains challenging. We herein assessed the fitness of commonly used clinical tests to evaluate glaucoma in KPro eyes versus eyes with penetrating keratoplasty (PK) as controls., Methods: Sixteen patients with KPro and 14 patients with PK tested in an identical manner. After the 10-2 visual field with size V stimulus, intraocular pressure (IOP) was estimated with palpation by the first observer. Then, retinal nerve fiber layer (RNFL) thickness analysis was performed twice using optical coherence tomography by an ophthalmic photographer, before and after a short break. After the second observer estimated the IOP, the visual field was repeated. Finally, color photographs of the optic disk were captured by an ophthalmic photographer. The cup-to-disk ratio was assessed by 2 masked observers, at 2 different time points, in a random manner. Agreements between and within observers and reliability of repeated measurements were evaluated using the intraclass correlation coefficient (ICC) and Bland-Altman plots., Results: Inter-rater agreement of palpation IOP estimate was moderate for eyes with KPro (ICC = 0.47) and fair for eyes with PK (ICC = 0.27). Visual field and RNFL thickness showed high test-retest reliability in both KPro and PK eyes (ICC > 0.80 for both). Inter-rater agreement of cup-to-disk ratio assessments was substantial in eyes with both KPro (ICC = 0.62) and PK (ICC = 0.70)., Conclusions: The 10-2 visual field and RNFL thickness seem sufficiently repeatable and might allow the detection of glaucoma progression in KPro eyes. Such testing is important, given limited inter-rater agreement regarding the palpation IOP estimate., Competing Interests: The authors have no funding or conflicts of interest to disclose., (Copyright © 2021 Wolters Kluwer Health, Inc. All rights reserved.)
- Published
- 2022
- Full Text
- View/download PDF
50. The Effect of Achieving Target Intraocular Pressure on Visual Field Worsening.
- Author
-
Villasana GA, Bradley C, Ramulu P, Unberath M, and Yohannan J
- Subjects
- Aged, Aged, 80 and over, Corneal Pachymetry, Disease Progression, Female, Glaucoma, Open-Angle diagnosis, Humans, Male, Middle Aged, Ocular Hypertension diagnosis, Ocular Hypertension physiopathology, Retrospective Studies, Risk Factors, Severity of Illness Index, Tonometry, Ocular, Vision Disorders diagnosis, Visual Field Tests, Glaucoma, Open-Angle physiopathology, Intraocular Pressure physiology, Vision Disorders physiopathology, Visual Fields physiology
- Abstract
Purpose: To estimate the effect of achieving target intraocular pressure (IOP) values on visual field (VF) worsening in a treated clinical population., Design: Retrospective analysis of longitudinal data., Participants: A total of 2852 eyes of 1688 patients with glaucoma-related diagnoses treated in a tertiary care practice. All included eyes had at least 5 reliable VF tests and 5 IOP measures on separate visits along with at least 1 target IOP defined by a clinician on the first or second visit., Methods: The primary dependent variable was the slope of the mean deviation (MD) over time (decibels [dB]/year). The primary independent variable was mean target difference (measured IOP - target IOP). We created simple linear regression models and mixed-effects linear models to study the relationship between MD slope and mean target difference for individual eyes. In the mixed-effects models, we included an interaction term to account for disease severity (mild/suspect, moderate, or advanced) and a spline term to account for the differing effects of achieving target IOP (target difference ≤0) and failing to achieve target IOP (target difference >0)., Main Outcome Measures: Rate of change in MD slope (changes in dB/year) per 1 mmHg change in target difference at different stages of glaucoma severity., Results: Across all eyes, a simple linear regression model demonstrated that a 1 mmHg increase in target difference had a -0.018 dB/year (confidence interval [CI], -0.026 to -0.011; P < 0.05) effect on MD slope. The mixed-effects model shows that eyes with moderate disease that fail to achieve their target IOP experience the largest effects, with a 1 mmHg increase in target difference resulting in a -0.119 dB/year (CI, -0.168 to -0.070; P < 0.05) worse MD slope. The effects of missing target IOP on VF worsening were more pronounced than the effect of absolute level of IOP on VF worsening, where a 1 mmHg increase in IOP had a -0.004 dB/year (CI, -0.011 to 0.003; P > 0.05) effect on the MD slope., Conclusions: In treated patients, failing to achieve target IOP was associated with more rapid VF worsening. Eyes with moderate glaucoma experienced the greatest VF worsening from failing to achieve target IOP., (Copyright © 2021 American Academy of Ophthalmology. Published by Elsevier Inc. All rights reserved.)
- Published
- 2022
- Full Text
- View/download PDF
Catalog
Discovery Service for Jio Institute Digital Library
For full access to our library's resources, please sign in.