Interactive Threshold Research Articles

Imaging software accuracy for 3-dimensional analysis of the upper airway

The aim of this study was to compare the precision and accuracy of 6 imaging software programs for measuring upper airway volumes in cone-beam computed tomography data. The sample consisted of 33 growing patients and an oropharynx acrylic phantom, scanned with an i-CAT scanner (Imaging Sciences International, Hatfield, Pa). The known oropharynx acrylic phantom volume was used as the gold standard. Semi-automatic segmentations with interactive and fixed threshold protocols of the patients' oropharynx and oropharynx acrylic phantom were performed by using Mimics (Materialise, Leuven, Belgium), ITK-Snap (www.itksnap.org), OsiriX (Pixmeo, Geneva, Switzerland), Dolphin3D (Dolphin Imaging & Management Solutions, Chatsworth, Calif), InVivo Dental (Anatomage, San Jose, Calif), and Ondemand3D (CyberMed, Seoul, Korea) software programs. The intraclass correlation coefficient was used for the reliability tests. A repeated measurements analysis of variance (ANOVA) test and post-hoc tests (Bonferroni) were used to compare the software programs. The reliability was high for all programs. With the interactive threshold protocol, the oropharynx acrylic phantom segmentations with Mimics, Dolphin3D, OsiriX, and ITK-Snap showed less than 2% errors in volumes compared with the gold standard. Ondemand3D and InVivo Dental had more than 5% errors compared with the gold standard. With the fixed threshold protocol, the volume errors were similar (-11.1% to -11.7%) among the programs. In the oropharynx segmentation with the interactive protocol, ITK-Snap, Mimics, OsiriX, and Dolphin3D were statistically significantly different (P <0.05) from InVivo Dental. No statistical difference (P >0.05) was found between InVivo Dental and OnDemand3D. All 6 imaging software programs were reliable but had errors in the volume segmentations of the oropharynx. Mimics, Dolphin3D, ITK-Snap, and OsiriX were similar and more accurate than InVivo Dental and Ondemand3D for upper airway assessment.

Progression Pattern of Initial Parafoveal Scotomas in Glaucoma

To characterize the progression pattern of initial parafoveal scotomas (IPFSs) using cross-sectional and longitudinal 10-2 visual field (VF) data. Retrospective, observational study. Glaucoma patients with an IPFS in either hemifield based on 2 reliable 24-2 Swedish interactive threshold algorithm standard VFs (≥3 adjacent points with P<0.05 within the central 10° of fixation, 1 point or more with P<0.01 lying at the innermost paracentral points, and no scotoma outside the central 10°) and at least 2 10-2 VFs (first and last VFs 1 year or more apart). To simulate a cohort with an extended follow-up, eyes with an IPFS were divided into subgroups based on the severity of glaucoma using their 10-2 VF pattern standard deviation (PSD). Cross-sectional data were used to create an average pattern deviation map that was generated by averaging pattern deviation map values of 10-2 VF point-by-point within each subgroup. Longitudinal data (eyes with 5 or more 10-2 VFs) was used to perform pointwise linear regression analysis of pattern deviation values. Patterns of IPFS progression were identified from these cross-sectional and longitudinal assessments. Average pattern deviation maps (cross-sectional) and maps of progression rates (longitudinal) in different disease severity subgroups. Eighty eyes (80 patients) and 40 eyes (40 patients) with an IPFS were included for cross-sectional and longitudinal analyses, respectively. The mean age ± standard deviation, 24-2 VF mean deviation, and 24-2 VF PSD for all eyes were 63±10 years, -3.27±2.18 dB, and 5.46±2.40 dB, respectively. Based on maps generated in both cross-sectional and longitudinal analyses, IPFS in the superior hemifield had an arcuate pattern initially that later deepened approximately 3° to 5° above fixation. The scotoma then elongated toward the physiologic blind spot and spread toward the nasal periphery, sparing the area corresponding to the papillomacular bundle. The IPFS in the inferior hemifield had a similar pattern, but was slightly farther from fixation. Superior and inferior IPFS have a similar characteristic pattern of progression, although the latter tend to be farther from fixation. Understanding these patterns should help in the management of such patients and in improving VF testing algorithms.

Relación funcional entre los puntos de sensibilidad retiniana de la perimetría automatizada en el glaucoma

ObjectiveTo study the correlation between the sensitivity threshold values of the different points assessed by the Humphrey visual field analyzer (24-2 Swedish interactive threshold algorithm [SITA] standard strategy) in glaucoma patients. Subjets, material and methodsProspective cross-sectorial study. One-hundred and four eyes of 104 glaucoma patients, defined by the appearance of the optic nerve head, were evaluated. Retinal threshold sensitivity points of standard automated perimetry (SA) with SITA standard 24-2 program were obtained. The upper and the lower hemifields were studied separately. Pearson correlation coefficients were calculated between the mean threshold sensitivity value at each point of the visual hemifield and the rest of the threshold points in the same hemifield. ResultsPerimetric correlation maps between retinal threshold sensitivity values in the same hemifield were obtained. Most of the points showed moderate to high correlations (r≥0.65. P<0.001) with neighboring points and distant points in the same hemifield. ConclusionsThere is a functional relationship between neighboring and distant points in Humphrey Visual Field Analyzer (SITA Standard 24-2) in glaucoma patients. This correlation is related to the anatomical arrangement of ganglion cell axons. This fact enables perimetric patterns of glaucoma defects to be obtained.

Factors That Influence Standard Automated Perimetry Test Results in Glaucoma: Test Reliability, Technician Experience, Time of Day, and Season

To determine the influence of several factors on standard automated perimetry test results in glaucoma. Longitudinal Humphrey field analyzer 30-2 Swedish interactive threshold algorithm data from 160 eyes of 160 glaucoma patients were used. The influence of technician experience, time of day, and season on the mean deviation (MD) was determined by performing linear regression analysis of MD against time on a series of visual fields and subsequently performing a multiple linear regression analysis with the MD residuals as dependent variable and the factors mentioned above as independent variables. Analyses were performed with and without adjustment for the test reliability (fixation losses and false-positive and false-negative answers) and with and without stratification according to disease stage (baseline MD). Mean follow-up was 9.4 years, with on average 10.8 tests per patient. Technician experience, time of day, and season were associated with the MD. Approximately 0.2 dB lower MD values were found for inexperienced technicians (P < 0.001), tests performed after lunch (P < 0.001), and tests performed in the summer or autumn (P < 0.001). The effects of time of day and season appeared to depend on disease stage. Independent of these effects, the percentage of false-positive answers strongly influenced the MD with a 1 dB increase in MD per 10% increase in false-positive answers. Technician experience, time of day, season, and the percentage of false-positive answers have a significant influence on the MD of standard automated perimetry.

Progression of Patterns (POP): A Machine Classifier Algorithm to Identify Glaucoma Progression in Visual Fields

We evaluated Progression of Patterns (POP) for its ability to identify progression of glaucomatous visual field (VF) defects. POP uses variational Bayesian independent component mixture model (VIM), a machine learning classifier (MLC) developed previously. VIM separated Swedish Interactive Thresholding Algorithm (SITA) VFs from a set of 2,085 normal and glaucomatous eyes into nine axes (VF patterns): seven glaucomatous. Stable glaucoma was simulated in a second set of 55 patient eyes with five VFs each, collected within four weeks. A third set of 628 eyes with 4,186 VFs (mean ± SD of 6.7 ± 1.7 VFs over 4.0 ± 1.4 years) was tested for progression. Tested eyes were placed into suspect and glaucoma categories at baseline, based on VFs and disk stereoscopic photographs; a subset of eyes had stereophotographic evidence of progressive glaucomatous optic neuropathy (PGON). Each sequence of fields was projected along seven VIM glaucoma axes. Linear regression (LR) slopes generated from projections onto each axis yielded a degree of confidence (DOC) that there was progression. At 95% specificity, progression cutoffs were established for POP, visual field index (VFI), and mean deviation (MD). Guided progression analysis (GPA) was also compared. POP identified a statistically similar number of eyes (P > 0.05) as progressing compared with VFI, MD, and GPA in suspects (3.8%, 2.7%, 5.6%, and 2.9%, respectively), and more eyes than GPA (P = 0.01) in glaucoma (16.0%, 15.3%, 12.0%, and 7.3%, respectively), and more eyes than GPA (P = 0.05) in PGON eyes (26.3%, 23.7%, 27.6%, and 14.5%, respectively). POP, with its display of DOC of progression and its identification of progressing VF defect pattern, adds to the information available to the clinician for detecting VF progression.

Effect of Multizone Refractive Multifocal Contact Lenses on Standard Automated Perimetry

The aim of this study was to evaluate whether the creation of 2 foci (distance and near) provided by multizone refractive multifocal contact lenses (CLs) for presbyopia correction affects the measurements on Humphreys 24-2 Swedish interactive threshold algorithm (SITA) standard automated perimetry (SAP). In this crossover study, 30 subjects were fitted in random order with either a multifocal CL or a monofocal CL. After 1 month, a Humphrey 24-2 SITA standard strategy was performed. The visual field global indices (the mean deviation [MD] and pattern standard deviation [PSD]), reliability indices, test duration, and number of depressed points deviating at P<5%, P<2%, P<1%, and P<0.5% on pattern deviation probability plots were determined and compared between multifocal and monofocal CLs. Thirty eyes of 30 subjects were included in this study. There were no statistically significant differences in reliability indices or test duration. There was a statistically significant reduction in the MD with the multifocal CL compared with monfocal CL (P=0.001). Differences were not found in PSD nor in the number of depressed points deviating at P<5%, P<2%, P<1%, and P<0.5% in the pattern deviation probability maps studied. The results of this study suggest that the multizone refractive lens produces a generalized depression in threshold sensitivity as measured by the Humphreys 24-2 SITA SAP.

Influence of multifocal intraocular lenses on standard automated perimetry test results

AbstractPurpose To evaluate the influence of multifocal intraocular lenses (MFIOLs) on standard automated perimetry (SAP) and size V perimetry test results.Methods Sixteen eyes of 16 patients with a diffractive MFIOL (median age 64 years) and 45 phakic eyes of 45 healthy subjects (median age 49 years) were included in this cross‐sectional case‐control study. All eyes underwent (1) SAP with the Humphrey Field Analyzer using a 30‐2 grid and the Swedish Interactive Threshold Algorithm standard strategy and (2) a full threshold test with stimulus size V (instead of the default size III). Our Main Outcome Measures were the mean deviation (MD; for SAP) and mean sensitivity (MS; for both SAP and size V perimetry).Results The MD of the SAP test results was on average 2.18 dB lower in MFIOL patients than in controls (P&lt;0.001). For all 16 cases and an age‐matched subgroup of 18 controls, this difference was 2.05 dB (P=0.001). The age‐adjusted difference in MS between cases and controls was ‐2.34 dB (P&lt;0.001). For size V perimetry, this was ‐1.67 dB (P&lt;0.001). For a subset of test locations within 10 degree eccentricity, the age‐adjusted difference in MS between cases and controls was ‐2.35 dB for size III (P&lt;0.001) and ‐1.96 dB for size V perimetry (P&lt;0.001).Conclusion Patients with a diffractive MFIOL have a clinically relevant reduction of the visual sensitivity as assessed with SAP and size V perimetry.

Patterns of Ganglion Cell Complex and Nerve Fiber Layer Loss in Nonarteritic Ischemic Optic Neuropathy by Fourier-Domain Optical Coherence Tomography

To characterize by Fourier-domain optical coherence tomography (FD-OCT) the loss of nerve fiber layer (NFL) and ganglion cell complex (GCC) in nonarteritic ischemic optic neuropathy (NAION). Patients diagnosed with NAION were enrolled and categorized into "superior field loss (SFL)," "inferior field loss (IFL)," and "bihemispheric field loss (BFL)" groups based on the Swedish interactive threshold algorithm 30-2 achromatic visual field (VF) tests. Six months after presentation, they were scanned by FD-OCT to map peripapillary NFL and macular GCC thicknesses. Age-matched normals were selected from participants in the Advanced Imaging for Glaucoma Study (www.AIGStudy.net). Deviation maps were defined as the difference between the thickness maps and the average normal maps. Pearson's correlation coefficient was used to assess the correlation between VF and OCT measurements. Twenty-five NAION eyes in 20 subjects were analyzed. Most (2/3) SFL cases showed inferior NFL loss with variable sparing of inferonasal losses. All (4/4) IFL cases showed superior NFL loss with variable inferonasal extension. The GCC maps demonstrated clear hemispheric loss pattern in agreement with VFs. NFL and GCC losses could be detected even in the less affected hemispheres (P < 0.001). NFL and GCC were highly correlated (P < 0.001) with VF in terms of both overall averages and superior-inferior hemispheric differences. NFL and GCC losses correlated well with VF losses in both magnitude and location. Hemispheric GCC loss correlated with altitudinal VF loss and this pattern may be of diagnostic value. FD-OCT is useful in the evaluation of NAION.

Adaptive Breast Radiation Therapy Using Modeling of Tissue Mechanics: A Breast Tissue Segmentation Study

To validate and compare the accuracy of breast tissue segmentation methods applied to computed tomography (CT) scans used for radiation therapy planning and to study the effect of tissue distribution on the segmentation accuracy for the purpose of developing models for use in adaptive breast radiation therapy. Twenty-four patients receiving postlumpectomy radiation therapy for breast cancer underwent CT imaging in prone and supine positions. The whole-breast clinical target volume was outlined. Clinical target volumes were segmented into fibroglandular and fatty tissue using the following algorithms: physical density thresholding; interactive thresholding; fuzzy c-means with 3 classes (FCM3) and 4 classes (FCM4); and k-means. The segmentation algorithms were evaluated in 2 stages: first, an approach based on the assumption that the breast composition should be the same in both prone and supine position; and second, comparison of segmentation with tissue outlines from 3 experts using the Dice similarity coefficient (DSC). Breast datasets were grouped into nonsparse and sparse fibroglandular tissue distributions according to expert assessment and used to assess the accuracy of the segmentation methods and the agreement between experts. Prone and supine breast composition analysis showed differences between the methods. Validation against expert outlines found significant differences (P<.001) between FCM3 and FCM4. Fuzzy c-means with 3 classes generated segmentation results (mean DSC = 0.70) closest to the experts' outlines. There was good agreement (mean DSC = 0.85) among experts for breast tissue outlining. Segmentation accuracy and expert agreement was significantly higher (P<.005) in the nonsparse group than in the sparse group. The FCM3 gave the most accurate segmentation of breast tissues on CT data and could therefore be used in adaptive radiation therapy-based on tissue modeling. Breast tissue segmentation methods should be used with caution in patients with sparse fibroglandular tissue distribution.

Optimal Design for the Precise Estimation of an Interaction Threshold: The Impact of Exposure to a Mixture of 18 Polyhalogenated Aromatic Hydrocarbons

Traditional additivity models provide little flexibility in modeling the dose-response relationships of the single agents in a mixture. While the flexible single chemical required (FSCR) methods allow greater flexibility, its implicit nature is an obstacle in the formation of the parameter covariance matrix, which forms the basis for many statistical optimality design criteria. The goal of this effort is to develop a method for constructing the parameter covariance matrix for the FSCR models, so that (local) alphabetic optimality criteria can be applied. Data from Crofton et al. are provided as motivation; in an experiment designed to determine the effect of 18 polyhalogenated aromatic hydrocarbons on serum total thyroxine (T(4)), the interaction among the chemicals was statistically significant. Gennings et al. fit the FSCR interaction threshold model to the data. The resulting estimate of the interaction threshold was positive and within the observed dose region, providing evidence of a dose-dependent interaction. However, the corresponding likelihood-ratio-based confidence interval was wide and included zero. In order to more precisely estimate the location of the interaction threshold, supplemental data are required. Using the available data as the first stage, the Ds-optimal second-stage design criterion was applied to minimize the variance of the hypothesized interaction threshold. Practical concerns associated with the resulting design are discussed and addressed using the penalized optimality criterion. Results demonstrate that the penalized Ds-optimal second-stage design can be used to more precisely define the interaction threshold while maintaining the characteristics deemed important in practice.

Prevalence of Primary Angle Closure and Primary Angle-Closure Glaucoma in a Southwestern Rural Population of Japan: The Kumejima Study

To determine the prevalence and ocular biometry of primary angle closure (PAC) and primary angle-closure glaucoma (PACG) in a rural population in southwestern Japan. Population-based cross-sectional study. All residents aged 40 years or older in Kumejima, Okinawa, Japan. Of the 4632 residents 40 years of age or older, 3762 (participation rate, 81.2%) underwent a detailed ocular examination, including measurement of the best-corrected visual acuity, slit-lamp examination, Goldmann applanation tonometry, static and dynamic gonioscopy, undilated stereoscopic optic fundus photographs, autorefractometry, partial coherence laser interferometry, noncontact specular microscopy, and screening visual field (VF) testing using frequency-doubling technology. If glaucoma or related or other ocular disorders were suspected, the subject was referred for a definitive examination including VF testing with the 24-2 Swedish Interactive Thresholding Algorithm Standard program of the Humphrey Field Analyzer (Carl Zeiss Meditec, Dublin, CA). Prevalence rates of primary angle-closure suspects (PACS), PAC, PACG, and PACG suspects. Under the standard definitions of the International Society of Geographical and Epidemiological Ophthalmology, the prevalence rates of PACS, PAC, and PACG were 8.8%, 3.7%, and 2.0%. Extending the diagnosis of PAC and PACG to include people with narrow but open angles and primary peripheral anterior synechiae, the prevalence rates of PAC and PACG increased to 6.0% and 2.2%, respectively. Hence, broadening the diagnostic categories in PAC and PACG increased the prevalence rates by 62% and 10%. Twenty-three subjects (0.6%; 95% confidence interval, 0.4%-0.9%) had a history of or were diagnosed with acute PAC. Older age, female gender, hyperopic refractive error, short axial length, and shallow anterior chamber depth were independent predictors of an occludable angle. The prevalence of PACG in Kumejima (2.2%) was one of the highest reported in population-based studies, that is, 3.7 times higher than in the Tajimi Study carried out in an urban center located in the central area of the main island of Japan. The author(s) have no proprietary or commercial interest in any materials discussed in this article.

A Population-based Survey of the Prevalence and Types of Glaucoma in Nepal: The Bhaktapur Glaucoma Study

To determine the prevalence and types of glaucoma in a Nepalese population. Cross-sectional, population-based survey. A total of 4800 subjects aged 40 years or older from the Bhaktapur district of Kathmandu valley. Subjects aged 40 years or older were selected using a cluster sampling procedure and door-to-door enumeration for a population-based, cross-sectional study. All subjects underwent a detailed ocular examination at the base hospital, which included logarithm of minimal angle of resolution visual acuity, refraction, applanation tonometry, gonioscopy, Lens Opacities Classification System II cataract grading, retinal examination, and Swedish Interactive Thresholding Algorithm standard perimetry when indicated. Diagnosis of glaucoma was based on criteria described by the International Society for Geographic and Epidemiological Ophthalmology. A total of 4003 subjects underwent a comprehensive eye examination (response rate 83.4%), and complete data were available in 3991 subjects. The mean intraocular pressure was 13.3 mmHg (97.5th and 99.5th percentiles, 18 and 20 mmHg, respectively), and the mean vertical cup-to-disc ratio was 0.26 (97.5th and 99.5th percentiles, 0.6 and 0.8 mmHg, respectively). There were 75 subjects with glaucoma, an age- and sex-standardized prevalence of 1.80 (95% confidence interval [CI], 1.68-1.92). Age- and sex-standardized prevalence was 1.24% (95% CI, 1.14-1.34) for primary open-angle glaucoma (POAG), 0.39% (95% CI, 0.34-0.45) for primary angle-closure glaucoma (PACG), and 0.15% (95% CI, 0.07-0.36) for secondary glaucoma. The prevalence of glaucoma increased with an increase in age with no significant difference in gender. Primary angle-closure glaucoma was 3 times more common in women. Nine eyes were blind, and 2 subjects were bilaterally blind from glaucoma. The overall prevalence of glaucoma was 1.9%. Of all glaucoma cases, POAG accounted for 68%, PACG accounted for 22.67%, and secondary glaucoma accounted for 9.33%. Among the subjects with POAG, 96.08% had not been previously diagnosed.

Mammographic density, parity and age at first birth, and risk of breast cancer: an analysis of four case–control studies

Mammographic density is strongly and consistently associated with breast cancer risk. To determine if this association was modified by reproductive factors (parity and age at first birth), data were combined from four case-control studies conducted in the United States and Japan. To overcome the issue of variation in mammographic density assessment among the studies, a single observer re-read all the mammograms using one type of interactive thresholding software. Logistic regression was used to estimate odds ratios (OR) while adjusting for other known breast cancer risk factors. Included were 1,699 breast cancer cases and 2,422 controls, 74% of whom were postmenopausal. A positive association between mammographic density and breast cancer risk was evident in every group defined by parity and age at first birth (OR per doubling of percent mammographic density ranged between 1.20 and 1.39). Nonetheless, the association appeared to be stronger among nulliparous than parous women (OR per doubling of percent mammographic density = 1.39 vs. 1.24; P interaction = 0.054). However, when examined by study location, the effect modification by parity was apparent only in women from Hawaii and when examined by menopausal status, it was apparent in postmenopausal, but not premenopausal, women. Effect modification by parity was not significant in subgroups defined by body mass index or ethnicity. Adjusting for mammographic density did not attenuate the OR for the association between parity and breast cancer risk by more than 16.4%, suggesting that mammographic density explains only a small proportion of the reduction in breast cancer risk associated with parity. In conclusion, this study did not support the hypothesis that parity modifies the breast cancer risk attributed to mammographic density. Even though an effect modification was found in Hawaiian women, no such thing was found in women from the other three locations.

Frequency Doubling Technology for Earlier Detection of Functional Damage in Standard Automated Perimetry-Normal Hemifield in Glaucoma With Low-to-Normal Pressure

To compare the longitudinal change of frequency doubling technology (FDT) perimetry and standard automated perimetry (SAP) results in SAP-normal hemifield in open-angle glaucoma (OAG) eyes with low-to-normal intraocular pressure (IOP). FDT perimetry with the N-30 full threshold protocol and SAP using the Humphrey Field Analyzer with the 30-2 Swedish Interactive Threshold Algorithm-standard protocol were periodically performed for at least 3 years in 39 eyes of 39 OAG patients with low-to-normal IOP and visual field damage confined to only one hemifield. The time courses of the mean of the threshold values of FDT and the mean of total deviations (TDs) in SAP-normal and SAP-abnormal fields were analyzed using a linear mixed model. The average follow-up was 4.9 years and the average IOP during follow-up was 12.6 mm Hg with or without medication. The aging effect-corrected rate of change in the mean FDT threshold values was significantly negative (P=0.004) in the SAP-normal hemifield, whereas that of mean of TD values by SAP did not significantly differ. In the SAP-abnormal hemifield, the rate of change was significantly negative for both tests (P<0.001). The mean of the slope of the mean TD values in the SAP-abnormal hemifield was significantly more negative than that in the SAP-normal hemifield (P=0.011), whereas that of the mean FDT threshold values showed no significant difference between the 2 hemifields. FDT is useful for monitoring functional damage in the SAP-normal hemifield in OAG eyes with low-to-normal IOP.

The C terminus of lettuce mosaic potyvirus cylindrical inclusion helicase interacts with the viral VPg and with lettuce translation eukaryotic initiation factor 4E.

Recessive resistance to lettuce mosaic virus (LMV) is conferred in lettuce by the mo1 gene, encoding the eukaryotic translation initiation factor 4E (eIF4E). The C terminus of the viral cylindrical inclusion helicase (CI-Cter), together with the VPg, is involved directly in overcoming mo1 resistance. In this study, recombinant LMV VPg and CI-Cter proteins from wild-type or resistance-breaking isolates were expressed and purified from Escherichia coli. The allelic forms of eIF4E from susceptible or resistant lettuce cultivars were produced similarly and these proteins were used in ELISA-based assays to demonstrate the in vitro binding of the various forms of LMV CI-Cter to both lettuce eIF4E and LMV VPg proteins. All combinations tested displayed significant and specific interactions, and the interaction between the C-terminal part of the LMV CI and eIF4E was confirmed in vivo in bimolecular fluorescence complementation assays. Higher interaction signals for both CI-eIF4E and CI-VPg were observed for LMV-E, indicating that the eIF4E interaction network involving CI and VPg appears to be stronger in the case of this resistance-breaking isolate. This could suggest the need for a minimal interaction threshold for infection success in resistant lettuce, but more precise measurement of the interaction parameters linking eIF4E, VPg and CI is needed in order to reinforce such a hypothesis.

Assessment of retinal sensitivity using a time-saving strategy in normal individuals

BackgroundThe purpose of this study was to compare retinal sensitivities in normal individuals obtained using the Swedish Interactive Threshold Algorithm Standard (SITA-S) on the Humphrey field analyzer with those obtained using the Dynamic strategy on the Octopus.MethodsPrior to visual field examinations, the background luminance, stimulus size, and exposure time with the Octopus 101 were conformed to the Humphrey field analyzer II settings. Volunteers over 20 years of age without apparent ophthalmic abnormalities were examined with the SITA-S central 30-2 program followed by the Dynamic 32 program. Eye with corrected visual acuity ≥ 0.8, refraction ≥ −6.0 diopters, and fields with satisfactory levels of reliability in SITA-S and Dynamic were selected.ResultsSixty-seven eyes from 67 normal individuals of mean age 51.3 ± 16.3 (range 22–76) years satisfied the selection criteria and were analyzed. Mean retinal sensitivity was significantly (P < 0.0001) higher with SITA-S (29.0 ± 2.4 dB) than with Dynamic (26.8 ± 2.1 dB). Changes in retinal sensitivity with increasing age were significantly (P = 0.0003) greater with Dynamic (−0.09 ± 0.04 dB/year; 95% confidence interval [CI] −0.10 to −0.08 dB/year) than with SITA-S (−0.07 ± 0.04 dB/year, 95% CI −0.08 to −0.06 dB/year). When classifying the visual field into three areas (central, mid-peripheral, and peripheral), retinal sensitivities with SITA-S were significantly higher in all areas than with Dynamic (P < 0.0001 for all three areas).ConclusionDifferences in Dynamic and SITA-S strategies may contribute to the differences in retinal sensitivities observed in normal individuals.

Optos‐guided pattern scan laser (Pascal)‐targeted retinal photocoagulation in proliferative diabetic retinopathy

To investigate the clinical effects and safety of targeted pattern scan laser (Pascal) retinal photocoagulation (TRP) in proliferative diabetic retinopathy (PDR). Prospective and non-randomized study of 28 eyes with treatment-naive proliferative diabetic retinopathy (PDR). Single-session 20-ms-Pascal TRP strategy applied 1500 burns to zones of retinal capillary non-perfusion and intermediate retinal ischaemia guided by wide-field fluorescein angiography (Optos). Main outcome measures at 12 and 24 weeks included; PDR grade (assessed by two masked retina specialists); central retinal thickness (CRT); mean deviation (MD) using 24-2 Swedish interactive threshold algorithm (SITA)-standard visual fields (VF); and ETDRS visual acuity (VA). Following primary TRP, there was PDR regression in 76% of patients at 12 weeks (κ = 0.70; p < 0.001). No laser re-treatment was required at 4 weeks, and 10 eyes underwent repeat TRP at 12 weeks. Wide-field Optos angiography at 24 weeks showed complete disease regression in 37% and partial regression in 33%. Additional panretinal laser photocoagulation (PRP) was planned for active PDR in 30%. There were significant reductions in CRT over time (10.4 μm at 12-weeks, p = 0.007; 12.1 μm at 24-weeks, p = 0.0003). The MD on VFs improved after 12 weeks (+1.25 dB; p = 0.015) and 24 weeks (+1.26 dB, p = 0.01). The VA increased by +3 letters at 24 weeks (95% CI, 1.74-5.01; p < 0.0001). This pilot study reports that Optos-guided Pascal 20-ms TRP using 1500 burns for treatment-naive PDR is a promising procedure with favourable safety profile.

Examination of the performance of different pointwise linear regression progression criteria to detect glaucomatous visual field change

We aimed to investigate the performance of five different trend analysis criteria for the detection of glaucomatous progression and to determine the most frequently and rapidly progressing locations of the visual field. Retrospective cohort. Treated glaucoma patients with ≥ 8 Swedish Interactive Thresholding Algorithm (SITA)-standard 24-2 visual field tests. Progression was determined using trend analysis. Five different criteria were used: (A) ≥ 1 significantly progressing point; (B) ≥ 2 significantly progressing points; (C) ≥ 2 progressing points located in the same hemifield; (D) at least two adjacent progressing points located in the same hemifield; (E) ≥ 2 progressing points in the same Garway-Heath map sector. Number of progressing eyes and false-positive results. We included 587 patients. The number of eyes reaching a progression end-point using each criterion was: A = 300 (51%); B = 212 (36%); C = 194 (33%); D = 170 (29%); and E = 186 (31%) (P ≤ 0.03). The numbers of eyes with positive slopes were: A = 13 (4.3%); B = 3 (1.4%); C = 3 (1.5%); D = 2 (1.1%); and E = 3 (1.6%) (P = 0.06). The global slopes for progressing eyes were more negative in Groups B, C and D than in Group A (P = 0.004). The visual field locations that progressed more often were those in the nasal field adjacent to the horizontal midline. Pointwise linear regression criteria that take into account the retinal nerve fibre layer anatomy enhances the specificity of trend analysis for the detection glaucomatous visual field progression.

Association Between Corneal Biomechanical Properties and Glaucoma Severity

To investigate the association between corneal biomechanical parameters using the Ocular Response Analyzer (ORA) and glaucoma severity. Observational cross-sectional study. Two hundred ninety-nine eyes of 191 patients with confirmed or suspect glaucoma were recruited at the University of California, San Diego. Corneal hysteresis (CH) and corneal resistance factor (CRF) were obtained from all participants. Standard automated perimetry was done using the 24-2 Swedish Interactive Threshold Algorithm. Retinal nerve fiber layer (RNFL) thickness measurements were obtained using GDx ECC and spectral-domain optical coherence tomography (SD-OCT). The association between ORA parameters and disease severity was evaluated using univariable and multivariable regression models. CH and CRF were both positively associated with mean defect (MD) (R(2) = 0.03; P < .01 and R(2) = 0.10; P < .01, respectively). In multivariable analysis, the association between CRF and MD remained significant while CH to MD did not (P < .01 and P = .77). In the GDx ECC subgroup (204 eyes), there was a weak association between CH and CRF and average RNFL thickness (R(2) = 0.07; P < .01 and R(2) = 0.05; P < .01, respectively), which was not observed in the SD-OCT subgroup (146 eyes) (R(2) = 0.01; P = .30 and R(2) = 0.01; P = .21). After adjusting for central corneal thickness, age, and axial length, the relationship of CH and CRF to RNFL thickness no longer reached statistical significance. The current study found only a weak relationship between corneal biomechanical parameters and measures of structural and functional damage in glaucoma.

Comparison of the corneal biomechanical properties with the Ocular Response Analyzer® (ORA) in African and Caucasian normal subjects and patients with glaucoma

To compare corneal hysteresis (CH) and corneal resistance factor (CRF) measured with the Ocular Response Analyzer(®) tonometer (ORA) between (i) African normals and treated primary open-angle glaucoma (POAG) patients and (ii) between normals and treated POAG Caucasians. To analyse the correlation of CH and CRF with visual field (VF) defects in the two groups. This comparative study included 59 African (29 (POAG), 30 normals) and 55 Caucasians (30 POAG and 25 normals) subjects. Goldmann applanation tonometry (GAT) and ORA measurements were performed in a randomized sequence. Visual field was tested with the Swedish interactive threshold algorithms standard strategy of the Humphrey perimeter. Hoddap classification was used to estimate the severity of VF defects. Primary open-angle glaucoma Africans were younger than POAG Caucasians (p < 0.001). Goldmann applanation tonometry and central corneal thickness (CCT) did not differ significantly between the four subgroups. African normals had lower CH than Caucasian controls (p < 0.001). CH was 9.2 ± 1.1 and 8.3 ± 1.7 mmHg respectively in POAG Caucasians and Africans (p < 0.001). African controls had higher ORA corneal-compensated intraocular pressure (IOPcc) than Caucasian controls (p < 0.001). Primary open-angle glaucoma Africans had higher IOPcc values than Caucasian POAGs (p < 0.001). CH and IOPcc were associated with race (p < 0.001) but not with CCT. Based on mean deviation values (MD), POAG Africans had more severe VF defects. CH was correlated with MD (r = 0.442; p = 0.031) and severity of VF defects only in POAG Africans (r = -0.464; p = 0.013). African normal subjects and POAG patients had an altered CH, which is associated with a significant underestimation of GAT IOP. This may potentially contribute to the earlier development and greater severity of glaucoma damage in Africans compared with Caucasians at diagnosis.