scholarly journals Functional visual fields: a cross-sectional UK study to determine which visual field paradigms best reflect difficulty with mobility function

BMJ Open ◽  
2017 ◽  
Vol 7 (11) ◽  
pp. e018831
Author(s):  
Hikmat Subhi ◽  
Keziah Latham ◽  
Joy Myint ◽  
Michael Crossland
Keyword(s):  
Visual Field ◽  
Visual Fields ◽  
Roc Curves ◽  
Secondary Outcome ◽  
Patient Acceptability ◽  
Cross Sectional ◽  
Mobility Function ◽  
Kinetic Assessment ◽  
Better Than ◽  
Mobility Difficulty

ObjectivesTo develop an appropriate method of assessing visual field (VF) loss which reflects its functional consequences, this study aims to determine which method(s) of assessing VF best reflect mobility difficulty.SettingThis cross-sectional observational study took place within a single primary care setting. Participants attended a single session at a University Eye Clinic, Cambridge, UK, with data collected by a single researcher (HS), a qualified optometrist.Participants50 adult participants with peripheral field impairment were recruited for this study. Individuals with conditions not primarily affecting peripheral visual function, such as macular degeneration, were excluded from the study.Primary and secondary outcome measuresParticipants undertook three custom and one standard binocular VF tests assessing VF to 60°, and also integrated monocular threshold 24–2 visual fields (IVF). Primary VF outcomes were average mean threshold, percentage of stimuli seen and VF area. VF outcomes were compared with self-reported mobility function assessed with the Independent Mobility Questionnaire, and time taken and patient acceptability were also considered. Receiver operating characteristic (ROC) curves determined which tests best predicted difficulty with mobility tasks.ResultsGreater VF loss was associated with greater self-reported mobility difficulty with all field paradigms (R20.38–0.48, all P<0.001). All four binocular tests were better than the IVF at predicting difficulty with at least three mobility tasks in ROC analysis. Mean duration of the tests ranged from 1 min 26 s (±9 s) for kinetic assessment to 9 min 23 s (±24 s) for IVF.ConclusionsThe binocular VF tests extending to 60° eccentricity all relate similarly to self-reported mobility function, and slightly better than integrated monocular VFs. A kinetic assessment of VF area is quicker than and as effective at predicting mobility function as static threshold assessment.

scholarly journals Prevalence and service assessment of cataract in Tibetan areas of Sichuan Province, China: population-based study

BMJ Open ◽  
2019 ◽  
Vol 9 (11) ◽  
pp. e031337 ◽  
Author(s):  
Danba Jiachu ◽  
Ling Jin ◽  
Feng Jiang ◽  
Li Luo ◽  
Hong Zheng ◽  
...  
Keyword(s):  
Visual Impairment ◽  
Response Rate ◽  
Rapid Assessment ◽  
Population Based ◽  
Cross Sectional Study ◽  
Secondary Outcome ◽  
Cross Sectional ◽  
Population Based Study ◽  
Low Prevalence ◽  
Better Than

ObjectivesTo assess the prevalence of visual impairment (VI) and blindness (BL) due to cataract and cataract surgical outcomes in remote dispersed and high-altitude Tibetan areas of China.Design and settingA cross-sectional study was conducted among people aged 50 and above in Tibetan Autonomous Prefecture of Kandze (TAPK), China, in 2017. The Rapid Assessment of Avoidable Blindness protocol was followed.ParticipantsOf 5000 eligible participants, 4764 were examined (response rate 95.3%).Primary and secondary outcome measuresCataract VI was defined as lens opacity at visual acuity (VA) levels of <3/60 (Blindness (BL)), ≥3/60 and <6/60 (severe visual impairment (SVI)), ≥6/60 and <6/18 (moderate visual impairment (MVI)), ≥6/18 and <6/12 (early visual impairment (EVI)).ResultsThe estimated prevalence of cataract BL was 0.61% (95% CI 0.42 to 0.87). With best corrected VA, the estimated prevalence of SVI from cataract was 0.86% (95% CI 0.63 to 1.17); MVI was 2.39% (95% CI 2.00 to 2.87) and EVI was 5.21% (95% CI 4.61 to 5.87). Women in TAPK had a significantly higher prevalence of cataract BL (0.82%, 95% CI 0.54 to 2.15) than men (0.34%, 95% CI 0.16 to 0.70). Women had lower cataract surgical coverage (CSC) by eyes (60.8%, 95% CI 55.5 to 65.8) compared with men (70.1%; 95% CI 63.7 to 75.7). The prevalence of cataract BL was higher among Tibetan (2.28%; 95% CI 1.98 to 2.62) than Han Chinese (1.01%%; 95% CI 0.54% to 1.87%). Overall CSC by person with BL (by better eye) was 82.0% (95% CI 75.2 to 87.6). Among cataract-operated participants, 71.2% had VA equal to or better than 6/18.ConclusionsThe study detected a low prevalence of VI and BL due to cataract with high CSC in the study area compared with many other places in China. Further actions should be taken to improve cataract surgical outcome.

Blindsight in Subjects with Homonymous Visual Field Defects

1999 ◽  
Vol 11 (1) ◽  
pp. 52-66 ◽  
Author(s):  
Heinz Schärli ◽  
Alison M. Harman ◽  
John H. Hogben
Keyword(s):  
Visual Field ◽  
Visual Fields ◽  
Neural Mechanism ◽  
Stray Light ◽  
Visual Field Defects ◽  
Optic Radiation ◽  
Visual Ability ◽  
Choice Tests ◽  
Visual Areas ◽  
Better Than

Brain damage in the visual system can lead to apparently blind visual areas. However, more elaborate testing indicates that some visual ability may still exist for specific stimuli in the otherwise blind regions. This phenomenon is called “blindsight” if subjects report no conscious awareness of visual stimuli but when forced to guess, nevertheless perform better than chance. It has mainly been suggested that secondary visual pathways are responsible for this phenomenon. However, no published study has clearly shown the neural mechanism responsible for blindsight. Furthermore, experimental artifacts may have been responsible for the appearance of the phenomenon in some subjects. In the present study, the visual fields of nine subjects were mapped and residual visual performance was examined in many areas using three different experimental procedures. Artifacts such as stray light or eye movements were well controlled. In addition, confidence ratings were required after each trial in the forced-choice tests. The results show that only one subject with a lesion in the optic radiation had blindsight in two discrete areas of the affected visual field. Spared optic radiation fibers of the main (primary) geniculo-striate visual pathway were most likely to account for this finding.

scholarly journals Visual Field Changes in Normal Tension Glaucoma (NTG)

2021 ◽  
Vol 15 (9) ◽  
pp. 2266-2267
Author(s):  
Ossama Ali Khan ◽  
Sajjad Mohammad ◽  
Imran Khan ◽  
Muhammad Faiq Nisar ◽  
Amir Khan ◽  
...  
Keyword(s):  
Visual Field ◽  
Open Angle Glaucoma ◽  
Visual Fields ◽  
Normal Tension Glaucoma ◽  
Cross Sectional Study ◽  
Sectional Study ◽  
Cross Sectional ◽  
Medical College ◽  
Paracentral Scotoma ◽  
The Right

Aim: To observe the visual field changes in normal tension glaucoma Study design: Cross sectional study Study site: Department of Physiology, Khyber Medical College, Peshawar Study period: six months Sample size: 100 cases were included who fulfil the criteria. Results: There were 33(33%) males and 67(67%) females in the study. Visual fields of eyes were investigated. It was revealed that in cases with the right eye problem, 67(67%) had paracentral scotoma, 27(27%) had superior & inferior nasal steps, 1(1%) had scotoma closer to fixation and 5(5%) had arcuate scotoma, while in the left eye cases, 67(67%) had paracentral scotoma, 30 (30%) had superior & inferior nasal steps, 1(1%) had scotoma closer to fixation and 2(2%) had arcuate scotoma. Conclusion: Visual fields of eyes revealed that in cases with the right eye problem, 67(67%) had paracentral scotoma, 27(27%) had superior & inferior nasal steps, 1(1%) had scotoma closer to fixation and 5(5%) had arcuate scotoma, while in the left eye cases, 67(67%) had paracentral scotoma, 30(30%) had superior & inferior nasal steps, 1 (1%) had scotoma closer to fixation and 2(2%) had arcuate scotoma. Keywords: Visual field, open angle glaucoma, normal tension glaucoma

Visual field inhomogeneous in brain-computer interfaces based on rapid serial visual presentation

2022 ◽  
Author(s):  
Shangen Zhang ◽  
Xiaogang Chen ◽  
Yijun Wang ◽  
Baolin Liu ◽  
Xiaorong Gao
Keyword(s):  
Visual Field ◽  
Visual Attention ◽  
Rapid Serial Visual Presentation ◽  
Visual Fields ◽  
Visual Presentation ◽  
Lower Visual Field ◽  
Horizontal Meridian ◽  
Vertical Meridian ◽  
Upper Visual Field ◽  
Better Than

Abstract Objective. Visual attention is not homogeneous across the visual field, while how to mine the effective EEG characteristics that are sensitive to the inhomogeneous of visual attention and further explore applications such as the performance of brain-computer interface (BCI) are still distressing explorative scientists. Approach. Images were encoded into a rapid serial visual presentation (RSVP) paradigm, and were presented in three visuospatial patterns (central, left/right, upper/lower) at the stimulation frequencies of 10Hz, 15Hz and 20Hz. The comparisons among different visual fields were conducted in the dimensions of subjective behavioral and EEG characteristics. Furthermore, the effective features (e.g. SSVEP, N2pc and P300) that sensitive to visual-field asymmetry were also explored. Results. The visual fields had significant influences on the performance of RSVP target detection, in which the performance of central was better than that of peripheral visual field, the performance of horizontal meridian was better than that of vertical meridian, the performance of left visual field was better than that of right visual field, and the performance of upper visual field was better than that of lower visual field. Furthermore, stimuli of different visual fields had significant effects on the spatial distributions of EEG, in which N2pc and P300 showed left-right asymmetry in occipital and frontal regions, respectively. In addition, the evidences of SSVEP characteristics indicated that there was obvious overlap of visual fields on the horizontal meridian, but not on the vertical meridian. Significance. The conclusions of this study provide insights into the relationship between visual field inhomogeneous and EEG characteristics. In addition, this study has the potential to achieve precise positioning of the target's spatial orientation in RSVP-BCIs.

scholarly journals Visual Field Loss Morphology in High- and Normal-Tension Glaucoma

2012 ◽  
Vol 2012 ◽  
pp. 1-8 ◽  
Author(s):  
Michele Iester ◽  
Fabio De Feo ◽  
Gordon R. Douglas
Keyword(s):  
Visual Field ◽  
Visual Fields ◽  
Visual Field Loss ◽  
Normal Tension Glaucoma ◽  
Blind Spot ◽  
Cross Sectional Study ◽  
Cross Sectional ◽  
High Tension ◽  
Significant Difference ◽  
Almost All

Purpose. To determine whether the patterns of visual field damage between high-tension glaucoma (HTG) and normal-tension glaucoma (NTG) are equivalent.Methods. In this retrospective cross-sectional study, fifty-one NTG and 57 HTG patients were recruited. For each recruited patient only the left eye was chosen. Glaucomatous patients had abnormal visual fields and/or glaucomatous changes at the optic nerve head. They were classified as HTG or NTG on the basis of intraocular pressure (IOP) measurements. Patients' visual fields were analyzed by using Humphrey Field Analyzer (HFA), program 30-2, full threshold. The visual field sensitivity values and the pattern deviation map values of the 72 tested points were considered. Then a pointwise analysis and an area analysis, based on the Glaucoma Hemifield test criteria, were performed, and a comparison between the two subgroups was made by Student’sttest.Results. Between NTG and HTG, no significant difference was found pointwise for almost all the visual field points, except for two locations. One was under the blind spot, and the other was in the inferior hemifield around the twenty-degree position. When area analysis was considered, three areas showed a significantly different sensitivity between HTG and NTG.Conclusions. These data suggested that there was no relevant difference in the pointwise analysis between NTG and HTG; however, when visual field areas were compared, no difference in paracentral areas was found between NTG and HTG, but superior nasal step and inferior and superior scotomata showed to be deeper in HTG than in NTG.

scholarly journals Ocular interaction in its relation to measurements of brightness threshold

1940 ◽  
Vol 128 (853) ◽  
pp. 552-559 ◽  
Keyword(s):  
Steady State ◽  
Visual Field ◽  
Light Stimulus ◽  
Visual Fields ◽  
Maximum Size ◽  
The Other ◽  
Great Care ◽  
High Brightness ◽  
Maxwellian View ◽  
Better Than

The question to which an answer is here sought is how far, if at all, the sensations from the two eyes of a subject add together in the measurement of brightness threshold. That is, do two eyes see better than one, or only equally well? Two aspects of the question have been investigated; first, the measurement of brightness threshold when the eyes are in equilibrium with a visual field of fixed brightness (steady state of adaptation); secondly, the measurement of the variation of brightness threshold with time after cutting off a conditioning field of more or less high brightness (changing state of adaptation). In an investigation of this kind the action of the eye pupils must be eliminated. This was done by the use of Maxwellian view for all visual fields, though the method of fixing the eye pupil at its maximum size by a mydriatic could also be used (Lythgoe and Phillips 1938). It was felt, however, that the Maxwellian view method was more generally satisfactory, though it necessitated more complicated apparatus and great care in equalizing the beams entering the two eyes. Consideration is also given to the effect of a light stimulus applied to one eye on threshold measurements made with the other eye.

scholarly journals Measurement of visceral fat and abdominal obesity by single-frequency bioelectrical impedance and CT: a cross-sectional study

BMJ Open ◽  
2021 ◽  
Vol 11 (10) ◽  
pp. e048221
Author(s):  
Zhengyang Xu ◽  
Yandong Liu ◽  
Chengxi Yan ◽  
Ruopei Yang ◽  
Li Xu ◽  
...  
Keyword(s):  
Visceral Fat ◽  
Visceral Obesity ◽  
Bioelectrical Impedance ◽  
Roc Curves ◽  
Cross Sectional Study ◽  
Secondary Outcome ◽  
Sectional Study ◽  
Body Composition Assessment ◽  
Cross Sectional ◽  
Scatter Plots

ObjectivesThe measurement of visceral fat (VF) is clinically important for the identification of individuals at high risk of visceral obesity-related health conditions. Bioelectrical impedance analysis (BIA) is a widely available and frequently used body composition assessment method, but there have been few validation studies for the measurement of VF. This validation study investigated agreement between BIA and CT for the assessment of VF in adults.DesignCross-sectional study.SettingBetween 2015 and 2016 in China.ParticipantsA total of 414 adults (119 men and 295 women) aged 40–82 years.Primary and secondary outcome measuresCT-visceral fat area (VFA) was derived at the L2-3 and umbilicus level and VFA cut-offs for visceral obesity applied. BIA measurements of visceral fat level were compared with CT VFA findings using scatter plots and receiver operator characteristic (ROC) curves.ResultsScatter plots showed poor agreement between BIA and CT-derived visceral fat measurements in both sexes (R=0.387–0.636). ROC curves gave optimum figures for sensitivity and specificity of 65% and 69% in women and 76% and 70% in men, respectively, for BIA to discriminate between adults with normal levels of VF and those with visceral obesity determined by CT.ConclusionBIA has limited accuracy for the assessment of VF in adults in practice when compared with the criterion method.

Tolerable rates of visual field progression in a population-based sample of patients with glaucoma

2017 ◽  
Vol 102 (7) ◽  
pp. 916-921 ◽  
Author(s):  
Angeliki Salonikiou ◽  
Panayiota Founti ◽  
Vassilis Kilintzis ◽  
Antonis Antoniadis ◽  
Eleftherios Anastasopoulos ◽  
...  
Keyword(s):  
Visual Field ◽  
Visual Impairment ◽  
Open Angle Glaucoma ◽  
Visual Fields ◽  
Field Tests ◽  
Population Based ◽  
European Population ◽  
Mean Deviation ◽  
Cross Sectional ◽  
Rate Of Progression

AimsTo provide population-based data on the maximum tolerable rate of progression to avoid visual impairment (maxTRoP_VI) and blindness (maxTRoP_BL) from open-angle glaucoma (OAG).MethodsParticipants with OAG in the Thessaloniki Eye Study (cross-sectional, population-based study in a European population) were included in the analysis. Visual impairment was defined as mean deviation (MD) equal to or worse than −12dB and blindness as MD equal to or worse than −24dB. Additional thresholds for visual impairment were tested. For each participant maxTRoP_VI was defined as the rate of progression which would not lead to visual impairment during expected lifetime. MaxTRoP_BL was defined accordingly. Both parameters were calculated for each OAG subject using age, sex, MD and life expectancy data. The eye with the better MD per subject was included in the analysis.ResultsAmong 135 subjects with OAG, 123 had reliable visual fields and were included in the analysis. The mean age was 73±6 years and the median MD was −3.65±5.28dB. Among those, 69.1% would have a maxTRoP_VI slower than −1dB/year and 18.7% would have a maxTRoP_VI between −1 and −2dB/year. Also, 72.4% would have a maxTRoP_BL slower than −2dB/year. For all tested thresholds for visual impairment, approximately 86% of the OAG study participants would not be able to tolerate a rate of progression equal to or faster than −2dB/year.ConclusionsThe majority of patients with glaucoma in our study would have a maximum tolerable rate of progression slower than −1dB/year in their better eye. Patient-tailored strategies to monitor the visual field are important, but raise the issue of feasibility with regard to the number of visual field tests needed.

scholarly journals Visual Outcomes after Endoscopic Pituitary Surgery in Patients Presenting with Preoperative Visual Deficits

2017 ◽  
Vol 78 (06) ◽  
pp. 461-465 ◽  
Author(s):  
Felipe Fredes ◽  
Gabriel Undurraga ◽  
Pablo Rojas ◽  
Felipe Constanzo ◽  
Carolina Lazcano ◽  
...  
Keyword(s):  
Visual Field ◽  
Pituitary Adenomas ◽  
Visual Fields ◽  
Pituitary Tumors ◽  
Visual Outcome ◽  
Field Evaluation ◽  
Complete Removal ◽  
Pituitary Surgery ◽  
Endoscopic Endonasal ◽  
Cross Sectional

Introduction Pituitary adenomas represent 15% of primary brain tumors. Visual disturbance is a common clinical manifestation of these neoplasms due, among other factors, to local mass effect on the optic system. Objective To evaluate changes of the visual fields in patients undergoing endoscopic endonasal approach (EEA) for pituitary adenomas and to find predictive factors for successful visual field outcome. Material and Methods This is a cross-sectional study. A review was conducted of medical records of consecutive patients with tumors of the sellar region undergoing EEA between January 2008 and December 2012 at the Skull Base Unit of Guillermo Grant Benavente Hospital, University of Concepción, Concepción, Chile, and who had undergone pre- and postoperative visual field evaluation. Results A total of 35 patients, with a mean age of 50.2 years, fulfilled the inclusion criteria. All patients had objective visual field disturbances before the surgery. Following surgery, 25 patients (71.4%) had favorable outcomes, whereas 8 (22.8%) had no change and 2 (5.8%) had an unfavorable outcome. Complete tumor removal was associated with a better visual outcome than those obtained after a subtotal removal. Discussion The EEA for pituitary tumors is particularly effective for visual field disturbances, with reported improvement rates ranging from 50 to 90%. Our series show similar results, with a 71.4% improvement of visual field disturbances. Conclusion This study adds further evidence to the current belief that EEA for pituitary adenomas is a safe and effective technique to improve visual field alterations. Complete removal of the tumor during surgery seems to be a predictive factor for a good visual outcome.

Characterization of Rh/Si multilayer structure by HREM and HAADF

1992 ◽  
Vol 50 (1) ◽  
pp. 122-123
Author(s):  
Y. Cheng ◽  
J. Liu ◽  
M.B. Stearns ◽  
D.G. Steams
Keyword(s):  
Normal Incidence ◽  
High Resolution Electron Microscopy ◽  
X Rays ◽  
Beam Direction ◽  
Cross Sectional ◽  
Optical Elements ◽  
Resolution Electron ◽  
Point To Point ◽  
Better Than

The Rh/Si multilayer (ML) thin films are promising optical elements for soft x-rays since they have a calculated normal incidence reflectivity of ∼60% at a x-ray wavelength of ∼13 nm. However, a reflectivity of only 28% has been attained to date for ML fabricated by dc magnetron sputtering. In order to determine the cause of this degraded reflectivity the microstructure of this ML was examined on cross-sectional specimens with two high-resolution electron microscopy (HREM and HAADF) techniques.Cross-sectional specimens were made from an as-prepared ML sample and from the same ML annealed at 298 °C for 1 and 100 hours. The specimens were imaged using a JEM-4000EX TEM operating at 400 kV with a point-to-point resolution of better than 0.17 nm. The specimens were viewed along Si [110] projection of the substrate, with the (001) Si surface plane parallel to the beam direction.

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