Detection Of Visual Field Defects Research Articles

Objective detection of visual field defects with multifrequency VEPs.

To correlate multifrequency pattern reversal VEPs in quadrants (QmfrVEPs) with perimetric field losses for objective detection of visual field losses. QmfrVEP measurements were performed using four LED-based checkerboard stimulators to stimulate the four quadrants of the visual field. QmfrVEPs were measured monocularly in 5 normal subjects and in 5 glaucoma patients who showed losses in conventional Octopus perimetry. The pattern reversal frequency varied slightly between the stimulators: (11.92, 12.00, 12.08 and 12.16 reversals/sec). The responses to the different stimuli were identified by discrete Fourier analysis. VEPs were recorded using different electrode configurations, and the recording with the highest signal-to-noise ratio (SNR) was used for further analysis. QmfrVEP responses from the different quadrants can be reliably measured and separated using the 0.08 reversals/sec interstimulus reversal frequency differences. The signal-to-noise ratio in the four quadrants was significantly correlated with the equivalent visual field losses obtained with perimetry (Spearman rank correlation: P < 0.001). In the five glaucoma patients, the SNR was reduced in 15 out of the 16 quadrants with a perimetric defect, in comparison to the results in quadrants of healthy subjects. This confirms the sensitivity of the procedure. QmfrVEP responses can be measured reliably. This pilot study suggests that high SNR values exclude visual field defects and that focal defects can be identified in glaucoma patients. www. gov . NCT00494923.

Detection of visual field defects using Eye Movement Pediatric Perimetry in children with intracranial lesions: feasibility and applicability

The study aimed at evaluating the feasibility of Eye Movement Pediatric Perimetry (EMPP) among children in detecting Visual Field Defects (VFDs) associated with Intracranial Lesions (IL). Healthy controls (n = 35) and patients diagnosed with IL (n = 19) underwent a comprehensive clinical evaluation followed by a Goldmann Visual Field (GVF) and a customised EMPP protocol. During EMPP, all the participants were encouraged to fixate on a central target and initiate Saccadic Eye Movement (SEM) responses towards randomly appearing peripheral stimuli. The SEM responses were recorded using an eye-tracking device and further inspected to calculate Performance Scores (PS), Saccadic Reaction Times (SRTs), and an EMPP Index (EMPI). The mean age (years) of the controls and cases were 7.3 (SD: 1.5) and 9.4 (SD: 2.4) respectively. Among the controls, the older children (≥7 years) showed statistically significantly faster SRTs (p = 0.008) compared to the younger group. The binocular EMPP measurements compared between the controls and the cases revealed no statistically significant differences in PS (p = 0.34) and SRT (p = 0.51). EMPP failed in 4 children because of data loss or unacceptably poor PS whereas GVF failed in 7 children due to unreliable subjective responses. Of the 16 reports, with regard to the central 30-degree VF, 63% of the outputs obtained from both methods were comparable. EMPP is a reliable method to estimate and characterise the central 30-degree VF in greater detail in children with IL. EMPP can supplement the conventional methods, especially in those children who fail to complete a long duration GVF test.

Screening for Glaucomatous Visual Field Defects in Rural Australia with an iPad.

Aim and objectiveDeveloping improved methods for early detection of visual field defects is pivotal to reducing glaucoma-related vision loss. The Melbourne Rapid Fields screening module (MRF-S) is an iPad-based test, which allows suprathreshold screening with zone-based analysis to rapidly assess the risk of manifest glaucoma. The versatility of MRF-S has potential utility in rural areas and during infectious pandemics. This study evaluates the utility of MRF-S for detecting field defects in non-metropolitan settings.Materials and methodsThis was a prospective, multicenter, cross-sectional validation study. Two hundred and fifty-two eyes of 142 participants were recruited from rural sites through two outreach eye services in Australia. Participants were tested using MRF-S and compared with a reference standard; either Zeiss Humphrey Field Analyzer or Haag-Streit Octopus performed at the same visit. Standardized questionnaires were used to assess user acceptability. Major outcome measures were the area under the curve (AUC) for detecting mild and moderate field defects defined by the reference tests, along with corresponding performance characteristics (sensitivity, specificity).ResultsThe mean test duration for MRF-S was 1.88 minutes compared with 5.92 minutes for reference tests. The AUCs for mild and moderate field defects were 0.81 [95% confidence interval (CI): 0.75–0.87] and 0.87 (95% CI: 0.83–0.92), respectively, indicating very good diagnostic accuracy. Using a risk criterion of 55%, MRF-S identified moderate field defects with a sensitivity and specificity of 88.4 and 81.0%, respectively.Conclusion and clinical significanceThe MRF-S iPad module can identify patients with mild and moderate field defects while delivering favorable user acceptability and short test duration. This has potential application within rural locations and amidst infectious pandemics.How to cite this articleChia MA, Trang E, Agar A, et al. Screening for Glaucomatous Visual Field Defects in Rural Australia with an iPad. J Curr Glaucoma Pract 2021;15(3):125–131.

Detection of Visual Field Defect Using Topographic Evoked Potential in Children

The interpretation of visual evoked potentials (YEP) suffers from a lack of objectivity due to several causes. First there is as yet no good biological model explaining the relation between the physiological activities occurring in the brain and the voltage variations measured during the YEP. This means that no mathe­matical standard for a "normal" reading has been set, nor a normal range of variation against which to test a YEP under investigation. There are certain features whose presence or absence are considered relevant to the analysis, like peak mor­phology and latency features, but these are difficult to code mathematically and it is not clear at all what their statistical dis­tributional properties are, both in the healthy population and in specific types of illnesses.

Multifocal Visual Evoked Potentials (mfVEP) for the Detection of Visual Field Defects in Glaucoma: Systematic Review and Meta-Analysis.

Some discrepancies have been observed in the diagnostic efficacy of multifocal visual evoked potential (mfVEP) when evaluating visual field defects in glaucoma patients. Therefore, we evaluated the diagnostic precision of the mfVEP in glaucoma to find its best diagnostic indicator. A systematic review and meta-analysis of quantitative studies published up to 1 April 2021 was performed. The methodological quality of the included articles was assessed. Publication bias analysis and heterogeneity tests were performed. The sensitivity, specificity and diagnostic odds ratio were calculated. The area under the curve (AUC) was calculated using the summary of receiver operating characteristics curve. Six studies with a total of 241 patients were included according to the inclusion and exclusion criteria. The AUC was 0.98. There was no evidence of publication bias or threshold effect. The pooled sensitivity and pooled specificity of the mfVEP amplitude for detection of visual field defects in all studies was 0.93 and 0.89, respectively. The positive and negative likelihood ratios of mfVEP amplitude were 6.56 and 0.08, respectively. The amplitude of mfVEP showed a good diagnostic precision in the prediction of visual field defects. Interocular mfVEP amplitude analysis can be a good diagnostic indicator for visual field study.

Detection of visual field defects by opticians - with Damato Multifixation Campimetry Online.

To study Damato Multifixation Campimetry Online (DMCO), an inexpensive online visual field test, used for screening at optician shops in Denmark. This was an evaluation of a diagnostic test and customers were included if minimum 50years old, with a visual acuity of minimum 0.5 and with less myopia than 6 D. Standard equipment was a computer, a wireless mouse and a computer monitor. We used the 'DMCO STANDARD 4,5' algorithm for screening. DMCO results were electronically transmitted to the authors. Customers with a positive DMCO test received an eye examination including the reference standard Humphrey Visual Field Analyzer 30-2 SITA Fast test. A subset of control participants with a negative DMCO test received the same examination in order to estimate the number of false and true negatives. DMCO specificity and sensitivity were estimated according to five reference standards with 95% confidence intervals. The population comprised 627 individuals, 381 women and 246 men, from 13 optician shops. Mean age was 62years (SD 7.4). DMCO was positive in 32 individuals and 27 individuals were classified as 'true positives' with diagnoses such as glaucoma, cataract and neurological visual field defects. Of the 595 individuals with a negative DMCO test, 110 were examined and nine individuals were classified as 'false negatives' according to diagnoses. Depending on reference the specificity was 97-99% and sensitivity was 14-69%. Screening with DMCO demonstrated high specificity, whereas sensitivity was unsatisfactory. Future studies with enough power to estimate the true sensitivity is needed.

GearVision: Smartphone Based Head Mounted Perimeter For Detection Of Visual Field Defects.

Automated visual field perimetry is widely used for the evaluation of visual field defects caused by ophthalmological and neurodegenerative diseases. This test is typically performed using the Humphrey Perimeter or Octopus Perimeter. However, their high cost and large footprint limit their use to the clinical setting. This in turn limits their reach especially in the context of screening in remote environments and personal setting. In this paper, we report the development and testing of GearVision, a portable, accessible and compact virtual reality based visual field perimeter. It enables regular visual field testing in a cost-effective and convenient manner. Currently, GearVision is meant to augment the existing perimetry system and hence facilitate the detection of visual field defects early and without expert supervision or the need for hospital visits. In addition to the development of standard 30-2 suprathreshold and full threshold perimetry tests, we have proposed methods to improve test reliability and compliance. These include optional rest intervals during the test to reduce errors caused by strain or fatigue and improved false positive estimation based on statistical analysis of a patient's response times. We have tested the proposed system on 21 subjects and validated its capability to detect visual field defects.

Diagnostic Performance and Repeatability of a Novel Game-Based Visual Field Test for Children.

To demonstrate utility of a game-based test ("Caspar's Castle") for the detection of visual field defects in children. A validity and reliability study was carried out at Manchester Royal Eye Hospital Pediatric Ophthalmology Outpatients Department. We recruited 108 children with no eye pathology (aged 4-12 years) and examined a single eye with the Caspar's Castle system using either normal thresholds or thresholds artificially adapted to recreate defects to assess diagnostic utility. Number of peripheral stimuli missed was used to determine sensitivity and specificity of artificial defect detection and to plot receiver-operator characteristic curves. A further 21 children (aged 4-16 years) with pathology were recruited and Caspar's fields compared qualitatively with established field testing. A total of 106 of the Caspar's Castle examinations were able to be performed twice and repeatability was determined through coefficient of repeatability and Bland-Altman chart. In diagnostic testing using children with no eye pathology, 45 children completed a test using normal thresholds and 43 with tests using artificial defects. Area under receiver-operator characteristic curves for artificial defect detection was 0.895. Of the 21 children with pathology, seven had completed standard Humphreys field testing and Caspar's Castle fields corresponded with each of these by expert opinion. Coefficient of repeatability for number of points missed across all cohorts of children (106 patients) was 6.9 (95% confidence interval: 6.16-8.07). The Caspar's Castle system of assessing visual fields using novel game-based strategies demonstrates encouraging levels of sensitivity, specificity, and reliability. It could help address current difficulties in perimetry in young children.

A comparison between Humphrey and frequency doubling perimetry for chiasmal visual field defects.

To evaluate and compare the diagnostic ability of frequency doubling technology perimetry (FDT) with standard automated perimetry (SAP) using Humphrey Field Analyser for the detection of visual field defects produced by chiasmal lesions. Fifteen patients with documented chiasmal disease and previously diagnosed of bitemporal hemianopia with Humphrey perimetry were prospectively evaluated. All of them underwent a new SAP (SITA 24-2) followed by FDT tests (C-20 threshold). Diagnostic criteria for hemianopia were established according to the total deviation plot and the threshold values of FDT. A patient was diagnosed with hemianopia if one or both criteria were met. Based on these criteria, FDT sensitivity was calculated. Testing time and global indexes for both perimetric strategies were compared. The sensitivity of FDT was 75.0% (18 out of 24 eyes); the criterion based on threshold values was met more often (70.83%) than the criterion based on the total deviation plot (50.0%). Linear correlation was better for the external column than for the internal column of the visual field. Testing time with FDT was 122.16 seconds shorter than with SAP (p<0.001). The mean value for mean deviation (MD) was -13.62 dB (SD 6.88) for SAP and -8.83 dB (SD 5.94) for FDT (p<0.001). Compared with standard automatic perimetry, FDT has a low sensitivity for detecting temporal hemianopias and also has more difficulty in defining the vertical limits of the defects. There f o re, it does not appear to be an adequate method for the detection of chiasmal visual field defects.

Optic Disk Drusen: Historical and Up-To-Date Aspects

Optic disc drusen are an important differential diagnosis in the diagnostic evaluation of a prominent optic nerve head. Drusen of the optic disc occur in 0.34 to 2.4 % of human individuals and manifest themselves bilaterally in three of four cases. Drusen are found six times more often within histological sections than on funduscopic examination. It is known that optic disc drusen can occur in familial clusters without any other pathological ophthalmic findings. They can also be associated with retinitis pigmentosa, or with the Joubert or Alagille syndromes. Non-invasive diagnostic tools include fundus-autofluorescence (AF), optical coherence tomography (OCT) and ultrasound. Drusen of the optic nerve head are asymptomatic in most cases, though transient ischemia can lead to transient visual impairment. In particular, superficial drusen can lead to profound visual field defects in adulthood. Regular ophthalmological follow-up examinations with tonometry and perimetry are recommended for the early detection of visual field defects. Radial optic neurotomy (RON) seems to be a therapeutic option in patients with acute deterioration of the visual field.

Evaluation of Hemifield Sector Analysis Protocol in Multifocal Visual Evoked Potential Objective Perimetry for the Diagnosis and Early Detection of Glaucomatous Field Defects

PurposeMultifocal visual evoked potential (mfVEP) is a newly introduced method used for objective visual field assessment. Several analysis protocols have been tested to identify early visual field losses in glaucoma patients using the mfVEP technique, some were successful in detection of field defects, which were comparable to the standard automated perimetry (SAP) visual field assessment, and others were not very informative and needed more adjustment and research work. In this study we implemented a novel analysis approach and evaluated its validity and whether it could be used effectively for early detection of visual field defects in glaucoma.MethodsThree groups were tested in this study; normal controls (38 eyes), glaucoma patients (36 eyes) and glaucoma suspect patients (38 eyes). All subjects had a two standard Humphrey field analyzer (HFA) test 24-2 and a single mfVEP test undertaken in one session. Analysis of the mfVEP results was done using the new analysis protocol; the hemifield sector analysis (HSA) protocol. Analysis of the HFA was done using the standard grading system.ResultsAnalysis of mfVEP results showed that there was a statistically significant difference between the three groups in the mean signal to noise ratio (ANOVA test, p < 0.001 with a 95% confidence interval). The difference between superior and inferior hemispheres in all subjects were statistically significant in the glaucoma patient group in all 11 sectors (t-test, p < 0.001), partially significant in 5 / 11 (t-test, p < 0.01), and no statistical difference in most sectors of the normal group (1 / 11 sectors was significant, t-test, p < 0.9). Sensitivity and specificity of the HSA protocol in detecting glaucoma was 97% and 86%, respectively, and for glaucoma suspect patients the values were 89% and 79%, respectively.ConclusionsThe new HSA protocol used in the mfVEP testing can be applied to detect glaucomatous visual field defects in both glaucoma and glaucoma suspect patients. Using this protocol can provide information about focal visual field differences across the horizontal midline, which can be utilized to differentiate between glaucoma and normal subjects. Sensitivity and specificity of the mfVEP test showed very promising results and correlated with other anatomical changes in glaucoma field loss.

Comparison of Octopus Semi-Automated Kinetic Perimetry and Humphrey Peripheral Static Perimetry in Neuro-Ophthalmic Cases

Aim. To compare semikinetic perimetry (SKP) on Octopus 900 perimetry to a peripheral static programme with Humphrey automated perimetry. Methods. Prospective cross-section study comparing Humphrey full field (FF) 120 two zone programme to a screening protocol for SKP on Octopus perimetry. Results were independently graded for presence/absence of field defect plus type and location of defect. Results. 64 patients (113 eyes) underwent dual perimetry assessment. Mean duration of assessment for SKP was 4.54 minutes ±0.18 and 6.17 ± 0.12 for FF120 (P = 0.0001). 80% of results were correctly matched for normal or abnormal visual fields using the I4e target versus FF120, and 73.5% were correctly matched using the I2e target versus FF120. When comparing Octopus results with combined I4e and I2e isopters to the FF120 result, a match for normal or abnormal fields was recorded in 87%. Conclusions. Humphrey perimetry test duration was generally longer than Octopus SKP. In the absence of kinetic perimetry, peripheral static suprathreshold programme options such as FF120 may be useful for detection of visual field defects. However, statokinetic dissociation may occur. Octopus SKP utilising both I4e and I2e targets provides detailed information of both the defect depth and size and may provide a more representative view of the actual visual field defect.

Comparison of Advanced Visual Field Defects Measured with the Tübingen Mobile Campimeter and the Octopus 101 Perimeter

To compare the results of advanced visual field defects (VFD) measured with the conventional reference perimeter Octopus 101 (O-101) and the new portable Tübingen Mobile Campimeter (TMC). Thirty-seven subjects (18 to 75 years), 13 with advanced arcuate scotomas, 12 with VFD respecting vertical meridians, 6 with concentric constriction and 6 healthy controls were included. First examination was with O-101: grid 30 degrees -NO, 192 stimuli, 10 cd/m(2) background luminance, stimulus size: Goldmann III (26'); second examination was with TMC: 84 stimuli (subset of grid 30 degrees -NO), stimulus size 34', stimulus luminance 320-370 cd/m(2), background luminance 8-20 cd/m(2). Pointwise accuracy (proportion of concordant locations), sensitivity, and specificity were estimated into 95% confidence intervals (CI) by averaging individual logits. Examination durations were compared. TMC results are highly concordant with O-101 results for all defect classes. For the entire sample, the percentage of discordant points (perceived with TMC but not with O-101) among all discordant points was 35% (CI: 30% to 40%). Analyzed by VFD pattern, accuracy was highest in healthy controls scotomas (97.9%; CI: 97% to 98.5%) and lowest in arcuate scotomas (80.6 %; CI: 77.3% to 83.5%). Sensitivity was highest in concentric constriction (94.5%; CI: 82.9% to 98.4%) and lowest in healthy controls (59.1%; CI: 26.3% to 85.3%). Specificity was highest in healthy controls (98.1%; CI: 96.6% to 98.9%) and lowest in concentric constriction (77.4%; CI: 62.1% to 87.7%). Mean examination time was 4.6 minutes (TMC) and 9.8 minutes (O-101). The results indicate that the TMC is a feasible device for detection of VFD.

Comparison of Standard Automated Perimetry with Matrix Frequency-Doubling Technology in Patients with Resolved Optic Neuritis

To examine performance characteristics of frequency-doubling perimetry (FDP) in comparison with standard automated perimetry (SAP) in patients with resolved optic neuritis in a short-term follow-up study. Comparative consecutive case series. Twenty patients with resolved optic neuritis and 20 healthy volunteers participated in this study. The subjects were patients who recovered normal vision (1.0 or better) after optic neuritis. The Swedish interactive thresholding algorithm 30-2 program was used for SAP and a full-threshold 30-2 program was used for FDP. Using both forms of perimetry, the mean deviation (MD), pattern standard deviation (PSD), and the percentage of abnormal points significantly depressed <0.5% in the total deviation probability plot were compared. The visual fields were divided into 5 zones, and the mean sensitivity in each zone in affected eyes was compared with that in healthy eyes of the volunteers within 2 weeks of vision recovery and in follow-up after 2 weeks and 2 and 5 months. Standard automated perimetry and FDP showed general depression in the fovea and extrafoveal areas. Correlations between SAP and FDP were statistically significant for MD (Pearson r>0.75; P<0.001) and PSD (r>0.6; P<0.005). Defects detected with FDP were larger than with SAP in 14 eyes (70 %). In follow-up after 2 weeks and again after 2 and 5 months, FDP indicated slower improvement in visual field defects in the fovea and extrafoveal areas, whereas SAP indicated rapid improvement in these defects. Frequency-doubling perimetry is at least comparable with and potentially more sensitive than SAP in detecting visual field defects in resolved optic neuritis. This short-term follow-up study in patients with resolved optic neuritis suggests that FDP detects characteristics of slower recovery more effectively than SAP in the fovea and extrafoveal areas. These properties may allow more accurate detection of visual field defects and may prove advantageous for monitoring of patients with resolved optic neuritis.

A Comparison between Humphrey and Frequency Doubling Perimetry for Chiasmal Visual Field Defects

Purpose To evaluate and compare the diagnostic ability of frequency doubling technology perimetry (FDT) with standard automated perimetry (SAP) using Humphrey Field Analyser for the detection of visual field defects produced by chiasmal lesions. Methods Fifteen patients with documented chiasmal disease and previously diagnosed of bitemporal hemianopia with Humphrey perimetry were prospectively evaluated. All of them underwent a new SAP (SITA 24-2) followed by FDT tests (C-20 threshold). Diagnostic criteria for hemianopia were established according to the total deviation plot and the threshold values of FDT. A patient was diagnosed with hemianopia if one or both criteria were met. Based on these criteria, FDT sensitivity was calculated. Testing time and global indexes for both perimetric strategies were compared. Results The sensitivity of FDT was 75.0% (18 out of 24 eyes); the criterion based on threshold values was met more often (70.83%) than the criterion based on the total deviation plot (50.0%). Linear correlation was better for the external column than for the internal column of the visual field. Testing time with FDT was 122.16 seconds shorter than with SAP (p&lt;0.001). The mean value for mean deviation (MD) was −13.62 dB (SD 6.88) for SAP and −8.83 dB (SD 5.94) for FDT (p&lt;0.001). Conclusions Compared with standard automatic perimetry, FDT has a low sensitivity for detecting temporal hemianopias and also has more difficulty in defining the vertical limits of the defects. Therefore, it does not appear to be an adequate method for the detection of chiasmal visual field defects.

Peristat: A Computer-Based Perimetry Self-Test for Cost-Effective Population Screening of Glaucoma

Purpose: Peristat is a virtual perimetry system that allows self-testing on any standard computer monitor via Internet connection. The sensitivity and specificity of Peristat to detect visual-field defects were compared to standard Humphrey Visual Field Analyzer data.Materials and methods: In this prospective, comparative observational case series, 58 eyes of 33 patients were examined. Semiquantitative analyses compared Peristat and Humphrey Visual-Field scores. The study evaluated patients with an established glaucoma diagnosis, as well as glaucoma suspects who had undergone comprehensive ophthalmologic examinations including prior office perimetry evaluation (Humphrey Field Analyzer). Inclusion criteria were (1) diagnosis or suspicion of glaucoma, (2) BCVA better than 20/200, (3) reliable performance on prior standardized office perimetry, and (4) CDR greater than 0.5. Computer literacy was not required, and more than 40% of the patients tested were computer illiterate, with no previous computer or Internet experience. A total of 58 eyes of 33 patients were tested with the Humphrey and the Peristat systems: 10 eyes of 5 patients without documented glaucomatous field loss and 48 eyes of 23 patients with mild-to-severe scotomas by standard 24-2 office perimetry. A standard computer setup was used with a 17" monitor, and the Peristat system was enabled through a remote connection with a server.Results: In vitro All patients completed the Peristat test without difficulty. Testing time varied between 2 and 5 min, tending to be longer with more severe visual-field defects. Test results were reviewed, in a masked fashion, by two glaucoma specialists and one general ophthalmologist. The Peristat demonstrated a high degree of correlation with the Humphrey system. Among the three reviewers, sensitivity ranged from 80% to 83%. In a second subanalysis in which cases with mild defects were excluded, the Peristat's sensitivity increased to 84%-86% while specificity remained between 94% and 97% for all three reviewers. Patients performed the Peristat test with similar facility to their Humphrey test. Fixation losses and test reliability were comparable for both tests.Conclusions: Peristat is a reliable self-test perimetry system that demonstrates high clinical utility for the detection of visual-field defects from glaucoma. Peristat could be a valuable public health tool for cost-effective screening of glaucoma.

Detection of visual field defects in patients after anterior temporal lobectomy for mesial temporal sclerosis-establishing eligibility to drive.

The aim of this study is to quantify visual field defects after temporal lobectomy for mesial temporal sclerosis and to establish eligibility for driving. Automated static perimetry was performed on 14 patients who had undergone anterior temporal lobectomy for mesial temporal sclerosis. Perimetry consisted of monocular Humphrey Field Analyser (HFA) 30-2 test and a binocular Esterman 120 test. Of the 14 patients, three had no loss or non-specific loss, eight had partial homonymous quadrantanopia, one had complete homonymous quadrantanopia and two had concentric loss attributable to vigabatrin, which may have masked any loss occurring due to surgery. Of these, only seven passed the standardised DVLA visual fields. Of the seven who failed DVLA visual field, one had complete quadrantanopia, four had partial quadrantanopia and two had concentric loss (due to vigabatrin). Visual field defects contribute a great deal in the reduction of the quality of life in patients who have had surgery for mesial temporal sclerosis. Potential surgically induced visual field defects that could preclude driving need to be discussed with each patient preoperatively. In our study 50% of patients did not meet the required DVLA standards.

The diagnostic significance of the multifocal pattern visual evoked potential in glaucoma.

The concept of objective perimetry is an exciting one because it strives to assess glaucoma damage without relying on psychophysical testing. The recent introduction of multifocal stimulus recording has enhanced our ability to examine the human visual field using electrophysiology. A multifocal pattern visual evoked potential can now be recorded, testing up to 60 sites within the central 25 degrees. The test requires only that the subject fixate on a target, while a cortically scaled dartboard pattern stimulus undergoes pseudorandom alternation within each of the test segments. In its present configuration the test requires at least 8 minutes recording time per eye. Modified bipolar electrode positions are required to ensure that adequate signals are detected from all parts of the visual field. In glaucoma patients, pattern visual evoked potential amplitudes have been shown to reflect visual field loss with reduction of signal amplitude in the affected areas. This technique represents the first major step toward objective detection of visual field defects in glaucoma.

Detecting early glaucomatous field defects with the size I stimulus and Statpac.

The influence of stimulus size and normal database on the detection of visual field defects in automated static threshold perimetry (Humphrey Field Analyzer) was investigated in 82 eyes having a diagnosis of normal, glaucoma suspect, or early glaucoma. Using a mathematically derived 'normal' database, which assumes constantly decreasing threshold sensitivities with increasing eccentricity, the size I stimulus showed significantly greater sensitivity than the size III stimulus for detecting small, shallow scotomata in the central visual field. The use of Statpac, which contains an empirically derived, age-related normal database, increased the sensitivity significantly over that of the size III stimulus (with its mathematical model), and to a degree similar to that of the size I stimulus. The results obtained with the size I stimulus were reproducible and independent of the patient's age. This study suggests a potential role for the size I stimulus in evaluating eyes having or at risk of developing early glaucomatous field loss.

Usefulness of the Henson Central Field Screener for the detection of visual field defects, especially in glaucoma.

The Henson Central Field Screener is a recently marketed, relatively inexpensive campimeter with semi-automated registration of responses. The strategy used is suprathreshold, eccentricity-compensated, multiple stimulus static perimetry. The clinical usefulness of this apparatus was tested in a number of glaucoma patients, glaucoma suspects and normals, as well as in subjects with other ocular disorders, for whom stable visual fields as tested with other perimeters were available. The results obtained with the Henson Screener are generally in agreement with the known defects. The apparatus has some drawbacks, however.