Perimetry In Glaucoma Research Articles

Persistence, spatial distribution and implications for progression detection of blind parts of the visual field in glaucoma: a clinical cohort study.

BackgroundVisual field testing is an essential part of glaucoma care. It is hampered by variability related to the disease itself, response errors and fatigue. In glaucoma, blind parts of the visual field contribute to the diagnosis but - once established – not to progression detection; they only increase testing time. The aims of this study were to describe the persistence and spatial distribution of blind test locations in standard automated perimetry in glaucoma and to explore how the omission of presumed blind test locations would affect progression detection.Methodology/Principal FindingsData from 221 eyes of 221 patients from a cohort study with the Humphrey Field Analyzer with 30–2 grid were used. Patients were stratified according to baseline mean deviation (MD) in six strata of 5 dB width each. For one, two, three and four consecutive <0 dB sensitivities in the same test location in a series of baseline tests, the median probabilities to observe <0 dB again in the concerning test location in a follow-up test were 76, 86, 88 and 90%, respectively. For <10 dB, the probabilities were 88, 95, 97 and 98%, respectively. Median (interquartile range) percentages of test locations with three consecutive <0 dB sensitivities were 0(0–0), 0(0–2), 4(0–9), 17(8–27), 27(20–40) and 60(50–70)% for the six MD strata. Similar percentages were found for a subset of test locations within 10 degree eccentricity (P>0.1 for all strata). Omitting test locations with three consecutive <0 dB sensitivities at baseline did not affect the performance of the MD-based Nonparametric Progression Analysis progression detection algorithm.Conclusions/SignificanceTest locations that have been shown to be reproducibly blind tend to display a reasonable blindness persistence and do no longer contribute to progression detection. There is no clinically useful universal MD cut-off value beyond which testing can be limited to 10 degree eccentricity.

Earthquakes, volcanoes and Nordic Congress of Ophthalmology

Those of you who remember the Nordic Congress of Ophthalmology in Reykjavik in 2000 will recall the 6.8 Richter scale earthquake on the first day of the congress and the 6.5 earthquake at the end of the Gala dinner. At the time the organizing committee apologized for only being able to arrange earthquakes and promised to do better the next time around. Now we have. A volcanic eruption has started in Eyjafjallajokull, a beautiful glacier on the south coast of Iceland. This is about 90 min by car from Reykjavik and I can tell you from personal experience that the view is spectacular and the experience breath-taking. Molten lava is spewing at least 150 meters into the air piling up a new pitch-black mountain and melting away the white snow and ice all around. The last time Eyjafjallajokull erupted in 1821 the eruption lasted for 2 years and we are optimistic that the eruption will be going full force throughout the summer and can be included in the social program of the Nordic Ophthalmology Meeting. There is even a possibility for Katla, a huge volcano in neighbouring Myrdalsjokull to become active. This enormous volcano has been known to follow Eyjafallajokull at least for the last thousand years. The volcanic eruption is more than hundred kilometres away from Reykjavik and presents no danger to the population or visitors. The preliminary program for the Nordic Meeting is available on http://www.NOK2010.is. It is a powerful program with speakers from the Nordic countries, Great Britain, Japan and United States. It includes cutting edge science such as the keynote lecture by Robert MacLaren in Oxfold on gene therapy and stem cells for retinal disease and the keynote lecture by Gerald Chader, USA, on emerging therapies for retinal degenerative diseases. Dr. Chader will also talk about retinal electronic prosthesis in a retinitis pigmentosa symposium. All subspecialties in ophthalmology will be presented. Bill Aylward from Moorfields Eye Hospital will discuss controversies in retinal detachment surgery in a key note lecture, and Paul Lichter from the United States will discuss clinical trials in glaucoma in another key note lecture. Charlotta Zetterström will give a key note on cataract surgery in the third world. The Acta Ophthalmologica honourary lecture will be given by Professor Anders Heijl and we presume he will discuss important issues in glaucoma. Experts in all of the Nordic Countries have organized symposia with outstanding Nordic and international speakers in all fields of ophthalmology including vitreoretinal surgery, dislocated lenses, strabismus, exfoliation glaucoma, tumours in the lacrimal system, age-related macular degeneration, retinal imaging, corneal cross linking, glaucoma surgery, retinopathy of prematurity, optic neuritis, cataract surgery, paediatric uveitis, ocular oncology, neovascular AMD, glaucoma physiology, keratoconus, congenital cataracts, lens opacities, uveitis, imaging in glaucoma and clinical physiological examinations, eye banking and corneal bio-engineering, orbital diseases, glaucoma perimetry, retinitis pigmentosa, glaucoma management, oxygen physiology, corneal grafting, diabetic retinopathy and rehabilitation after stroke. The preliminary program is seen on the next page. It is not only the volcanic eruptions and the scientific program that should encourage you to come to Reykjavik this summer. As you may recall from 2000, even strong earthquakes do not cause any collapses in Iceland. Our houses are strongly built and do not collapse even in strong earthquakes. The same cannot be said for our banks, which indeed have collapsed and along with it the value of the Icelandic Krona. This means that you get more than twice as much for your Danish, Swedish or Norwegian Krona or Euro compared to last time which means that prices in Iceland have gone from being ridiculously expensive to being quite reasonable or even cheap. At the same time it must be stated that there is no collapse in Icelandic society. The economy is humming along nicely, all services are in place and indeed tourism is thriving better than ever. We look forward to seeing you in Reykjavik on August 4–7, 2010. Some of you may want to stay for the ARVO summer meeting on diabetic retinopathy a week later and I hope many of you will use the opportunity to bring your families and enjoy a wonderful summer in Iceland and a spectacular volcanic eruption. Happy summer.

Valor predictivo del Heidelberg Retina Tomograph III en pacientes con glaucoma incipiente o sospecha de glaucoma

Purpose To study the ability of Heidelberg Retina Tomography III (HRT 3) measurements to predict perimetry changes in patients with early glaucoma or suspected primary open-angle glaucoma. Material and methods One hundred and thirty two eyes with early glaucoma or suspected glaucoma with no changes in basal perimetry were prospectively selected and periodically evaluated over five years. The eyes were divided in two groups depending on the presence or absence of progression (changes in glaucoma perimetry). The association between morphometric parameters and baseline HRT 3 indices, glaucoma probability score (GPS) and Moorefield's Regression Analysis (MRA), and perimetry progression were studied using Cox multivariate regression analyses. Kaplan-Meier curves were used to illustrate the results. Results Forty-eight eyes (36.36%) showed perimetry progression. Perimetry progression showed higher correlations with the disc area (p = 0.001), the cup area (p = 0.002) and the vertical cup disc area (p = 0.001). Multivariate regression analyses showed that eyes with baseline MRA or baseline GPA changes were at a higher risk of having perimetry abnormalities and a faster progression. Conclusions MRA and GPA indices are useful to predict perimetry progression in patients with early primary open-angle glaucoma or suspected glaucoma. These indices can be used as risk markers of functional progression in glaucoma.

Ability of Heidelberg Retina Tomograph III to predict progression in patients with early glaucoma or suspected primary open-angle glaucoma

PurposeTo study the ability of Heidelberg Retina Tomography III (HRT 3) measurements to predict perimetry changes in patients with early glaucoma or suspected primary openangle glaucoma. Material and methodsOne hundred and thirty two eyes with early glaucoma or suspected glaucoma with no changes in basal perimetry were prospectively selected and periodically evaluated over five years. The eyes were divided in two groups depending on the presence or absence of progression (changes in glaucoma perimetry).The association between morphometric parameters and baseline HRT 3 indices, glaucoma probability score (GPS) and Moorefield's Regression Analysis (MRA), and perimetry progression were studied using Cox multivariate regression analyses. Kaplan-Meier curves were used to illustrate the results. ResultsForty-eight eyes (36.36%) showed perimetry progression. Perimetry progression showed higher correlations with the disc area (p=0.001), the cup area (p=0.002) and the vertical cup disc area (p=0.001). Multivariate regression analyses showed that eyes with baseline MRA or baseline GPA changes were at a higher risk of having perimetry abnormalities and a faster progression. ConclusionsMRA and GPA indices are useful to predict perimetry progression in patients with early primary open-angle glaucoma or suspected glaucoma. These indices can be used as risk markers of functional progression in glaucoma

Functional correlation between retinal sensitivity threshold values of standard automated perimetry in glaucoma

Abstract Purpose To study the interrelationship among the 52 retinal sensitivity threshold values of the Humphrey visual field analyzer with the 24‐2 Swedish interactive threshold algorithm (SITA) standard strategy in glaucoma patients. Methods Prospective cross‐sectorial study. 104 eyes of 104 patients with diagnosed glaucoma by means of optic disc stereophotographs were evaluated. Each 52 threshold points of the SITA Standard 24.2 program in the standard automated perimetry (SAP) were obtained. The upper and the lower hemifield were studied separately. Pearson correlation coefficients were calculated between each of the mean threshold values at each point of the visual hemifield and the rest of the threshold points. Results Perimetric correlation maps between threshold values in the same hemifield were obtained. Most of the points had moderate and high correlations (r ≥ 0,65) with neighboring points and distant points corresponding to the retinotopic distribution of the retinal nerve fibers. Conclusion There is a functional relationship, in glaucoma patients SAP, between neighboring and distant threshold points in corresponding to the anatomical arrangement of ganglion cells axons. This enables to achieve perimetric patterns of glaucoma defects.

The Groningen Longitudinal Glaucoma Study. II. A prospective comparison of frequency doubling perimetry, the GDx nerve fibre analyser and standard automated perimetry in glaucoma suspect patients

We aimed to determine prospectively the incidence of abnormal test results on frequency doubling perimetry (FDT), the nerve fibre analyser (GDx) and standard automated perimetry (SAP) in a cohort of glaucoma suspect patients with normal findings for all these tests at baseline. Seventy glaucoma suspect patients were followed prospectively for 4 years with SAP (Humphrey field analyser 30-2 SITA Fast), FDT (C-20 full-threshold) and GDx (Version 2.010) in a clinical setting. All patients had normal baseline test results on SAP, FDT and GDx. After the follow-up period, the number of patients who converted (whose test results changed from normal at baseline to reproducibly abnormal during follow-up) were counted for each technique and then compared. The cut-off point for FDT was > 1 depressed test-point p < 0.01 in the total deviation probability plot; the cut-off point for GDx was the Number > 29. Of the 70 glaucoma suspect patients, three converted on FDT, 14 on GDx and six on SAP. These proportions are significantly different for GDx versus SAP (p = 0.033) and GDx versus FDT (p = 0.002), but not for FDT versus SAP (p = 0.256). The most frequent finding after a 4-year follow-up was conversion on GDx.

ATD perimetry in glaucoma and ocular hypertensive patients. A preliminar study

Abstract Purpose: The new ATD perimetry assesses contrast sentivity thresholds for the three afferent sensory pathways of the visual system. Our aim is to compare contrast sensitivity to stimuli with different spatio‐temporal frequencies in glaucomatous (G) and ocular hypertensive (OHT) subjects. Methods: Twenty three G and OHT subjects were selected from the ophthalmic clinic, all subjects signed an informed consent. Inclusion criteria were diagnosis of G or OHT, normal Farnsworth‐Munsell color test, ametropia less than 6 D, visual acuity over 20/30, absence of previous ocular surgery and experience in perimetry. Twenty locations and the fovea were evaluated in a 60º x 40º fovea‐centered field. Eight gabor stimuli were used: 0.5cpd‐12Hz, 0.5cpd‐24Hz, 4cpd‐2Hz and 4cpd 12Hz, modulated along the achromatic (A) direction, 0.5cpd‐12Hz and 4cpd‐2Hz along the red/green (T) and blue/yellow (D) directions. Statistical analysis included ANOVA and Schéffé tests. Results: Mean thresholds for G and OHT were respectively, 0.4872 ± 0.5323 and 0.1077 ± 0.1922, for A 0.5cpd‐12Hz; 0.7296 ± 0.5925 and 0.2280 ± 0.2246 for stimulus A 0.5cpd‐24Hz; 1.4444 ± 0.5244 and 1,2671 ± 0.6138 for A 4cpd‐2Hz; and 0.7751 ± 0.1937 and 0.6851 ± 0.2379 for D 0.5cpd‐12Hz. Significant statistical differences (p&lt;0.05) were found between G and OHT groups only with these stimuli. Conclusions: These preliminary results show that certain stimuli may differentiate between G and OHT subjects. A larger population sample, including glaucoma suspects, is currently under study.

Progression detection in glaucoma can be made more efficient by using a variable interval between successive visual field tests

This study aimed to gain insight into the optimal spacing in time for visual field tests for progression detection in glaucoma. Three perimetric strategies for progression detection were compared by means of simulation experiments in a theoretical cohort. In strategies 1 and 2, visual field testing was performed with fixed-spaced inter-test intervals, using intervals of 3 and 6 months respectively. In strategy 3, the inter-test interval was kept at 1 year as long as the fields appeared unchanged. Then, as soon as progression was suspected, confirmation or falsification were performed promptly. Follow-up fields were compared against a baseline assuming linear deterioration, using various progression criteria. Outcome measures were: (1) specificity, (2) time delay until the diagnosis of definite progression, and (3) number of required tests. Strategies 2 and 3 had a higher specificity than strategy 1. Strategies 1 and 3 detected progression earlier than strategy 2. The number of required visual field tests was lowest for strategy 3. Perimetry in glaucoma can be optimised by postponing the next test under apparently stable field conditions and bringing the next test forward once progression is suspected.

Selective perimetry in glaucoma diagnosis

Selective perimetry evaluates visual function by using visual stimuli that attempt to target specific subpopulations of retinal ganglion cells, which is designed to improve sensitivity to detect glaucomatous functional loss. This paper reviews recent studies that have assessed the characteristics of new strategies/programs of selective perimetry. Selective perimetry is usually compared against an existing standard technique--standard automated perimetry. Recent studies did not consider standard automated perimetry results as part of inclusion/exclusion criteria, avoiding selection bias and permitting fair comparisons between perimetry techniques. Furthermore, the Swedish Interactive Threshold Algorithm is replacing Full-Threshold as the standard automated perimetry gold-standard strategy, and comparisons of the diagnostic performance of function-specific perimetry may be influenced by which standard automated perimetry technique is used as the reference. These factors may impact our perception about the role of selective perimetry in glaucoma management. The lack of a perfect gold-standard diagnostic test for glaucoma limits the interpretation of results from cross-sectional studies evaluating visual field tests. Nevertheless, evidence suggests that visual dysfunction in eyes with early glaucoma varies significantly between individuals and no single technique is superior to the others in all patients. A multimodal functional assessment may be more effective in detecting/quantifying visual impairment associated with early glaucoma.

Effects of lens opacity on AccuMap multifocal objective perimetry in glaucoma

To investigate the effect of lens opacity on the performance of the multi-focal visual evoked potential (mfVEP) test in patients with glaucoma and its relationship with the Humphrey's automated static perimetry. This is a prospective, non-randomized study. Twenty-two patients were enrolled with moderate cataract and primary glaucoma scheduled for cataract surgery with or without glaucoma surgery. Humphrey visual field and mfVEP test were preformed before surgery and after 6 - 8 weeks of post-operation. Lens opacity was evaluated with slit lamp according to LOCS III (lens opacity classification system, version III) by the same ophthalmologist. The improvement of AccuMap objective visual field was noted after lens removal in glaucoma patients. The amplitude of the AccuMap was significantly (P < 0.01) increased after cataract surgery compared to pre-operation (382.6 nV +/- 146.7 nV vs 308.0 nV +/- 96.6 nV). AccuMap severity index (ASI) was significantly (P < 0.001) decreased following lens removal compared with pre-operation (48.6 +/- 42.4 vs 90.0 +/- 54.8, P < 0.001). Latency was little changed before and after surgery (1207.5 ms +/- 67.7 ms, 1191.2 ms +/- 61.9 ms, respectively, P = 0.289). There were no correlations between the changes of amplitude and the degree of lens opacity (Spearman correction, P = 0.09). For Humphrey visual field, the mean deviation (MD) of pre- and post-operative was significantly (P < 0.001) affected by lens opacity (-12.2 +/- 7.8, -9.6 +/- 8.8, respectively, P < 0.001), but pattern standard deviation (PSD) had no such changes (6.5 +/- 3.2, 6.3 +/- 4.0, respectively, P = 0.748). There were well correlated between the ASI and the MD both pre- or post-operation (Pearson correction, P = 0.013, P < 0.001), and between the ASI changes and the MD changes after lens removal (Pearson correction, P = 0.017). Lens opacity affects the AccuMap objective visual field in patients with glaucoma, especially the amplitude of the AccuMap. The ASI is sensitively correlated with the MD of Humphrey perimetry.

Diagnostic Accuracy and Reproducibility of Tendency Oriented Perimetry in Glaucoma

To evaluate the diagnostic capability of tendency oriented perimetry (TOP) in glaucoma. A): The diagnostic accuracy of mean defect (MD), square-root of the loss variance (s LV), and number of pathologic points (NPP) was calculated in 295 normal and 414 glaucoma eyes (179 early, 112 moderate, and 123 advanced) examined with TOP. B): Threshold fluctuation (F) and its relationship with the loss variance (LV) was measured in 34 normal and 33 glaucoma eyes (mean MD=3 dB; SD=3.9) for TOP and for full-threshold perimetry (FT). C): Twenty-eight eyes with stable glaucoma (mean MD=9.5 dB; SD=7.2) were examined six times to quantify LV error. D): TOP and FT were tested with the simulation program PeriSim using different behavior models. A): The best diagnostic index in early glaucoma (MD<6dB) was sLV (specificity=90.2%, sensitivity=84.9). The three indices had similar precision in moderate and severe glaucoma. B): Threshold fluctuation and sLV were better correlated in TOP (r=0.72, p<0.01) than in FT (r=0.62, p<0.01). For normal subjects, in FT the incidence of F<2 dB was 8.82% and s LV<1.5 dB 5.88%. The same frequencies in TOP were 67.65% and 55.88%. C): Averaging six examinations reduced the sLV val ue by 22%. D): The threshold estimation error increased 1 dB in TOP in relation to FT for the same patient's behavior, but the error in TOP was lower than i n FT when the worst behavior was modeled. TOP is a good discriminator between glaucoma and normality. Perimetry results overestimate the real sLV value. TOP's high diagnostic ability is probably associated to the algorithm design and to less contaminating influences during the examination.

Automated flicker perimetry in glaucoma using Octopus 311: a comparative study with the Humphrey Matrix

We evaluated the clinical usefulness of flicker perimetry in glaucoma and glaucoma suspect patients using the new Octopus 311 automated perimeter. A total of 52 eyes of 52 glaucoma patients, 26 eyes of 26 glaucoma suspect patients and 61 eyes of 61 normal subjects were examined using standard automated perimetry (SAP), flicker perimetry and frequency doubling technology (FDT) perimetry. Flicker perimetry was performed using the Octopus 311 and its remote software package. Suprathreshold four-zone probability strategy was used to classify the critical fusion frequency probability level. The classified levels were set at 5% and 1% of probability of normality and 5 Hz. Frequency doubling technology perimetry was performed using 24-2-5, 24-2-1, N-30-5, N-30-1 screening programs using Humphrey Matrix perimetry. Standard automated perimetry was performed using the Humphrey field analyser program 24-2 full threshold. Optical coherence tomography using Stratus OCT was used for evaluating the retinal nerve fibre layer thickness in all glaucoma and glaucoma suspect patients. Receiver operating characteristic (ROC) curves were calculated. In the early stage of glaucoma, the areas under the ROC curve (AUCs) were 0.96 in flicker and 0.90 in Matrix perimetry. In the moderate and advanced stages of glaucoma, the AUCs were almost 1.0 in all tests. In glaucoma suspect patients, the AUC of the 5% probability level in flicker was significantly higher than in Matrix perimetry. The four-zone probability strategy using the Octopus 311 is a useful method for evaluating the flicker field in early glaucoma and glaucoma suspect patients.

Towards an optimal perimetric strategy for progression detection in glaucoma: from fixed-space to adaptive inter-test intervals

The aim was to compare two perimetric strategies for progression detection in glaucoma. Two perimetric strategies for progression detection were compared by means of a thought experiment in a theoretical cohort. In strategy I, visual field testing is performed with fixed-space inter-test intervals at a frequency of two tests per year. In strategy II, the frequency of visual field testing is set to one test per year as long as the fields are apparently unchanged, whereas as soon as progression is suspected, confirmation or falsification is performed within a short time span. Outcome measures were the time delay between the progression event and the diagnosis of definite progression, and the number of visual field tests performed per patient per year. Average time delay between the actual progression event and the final diagnosis of definite progression was 15 months in the case of strategy I and 6 months in the case of strategy II. Maximum time delays were 18 and 12 months respectively. The frequency of visual field testing was 2 tests per patient per year for strategy I and 1.45 tests per patient per year for strategy II. Perimetry in glaucoma can be optimised by postponing the next test in the case of an apparently stable field and accelerating the next test in the case of a suspected progression. This results in an earlier diagnosis, a lower perimetric frequency and a shorter period of uncertainty for the patient.

Relationship of SITA and Full-Threshold Standard Perimetry to Frequency-Doubling Technology Perimetry in Glaucoma

To compare full-threshold (FT) and SITA algorithms for standard automated perimetry (SAP) with frequency-doubling technology perimetry (FDT) in glaucoma, to help clinicians to relate results in patients who have had two or more of these tests during follow-up. This study was a retrospective analysis of data from a longitudinal prospective study at the University of California, San Diego. One hundred four eyes of 104 patients with glaucomatous optic neuropathy detected by optic disc stereophotographs were included. All patients had standard perimetry (SITA and FT) and FDT within 3 months of each other. Global indices, abnormality and severity using two threshold algorithms of standard perimetry were compared with FDT. More eyes had normal visual fields by SAP-FT (57 eyes) than by either SAP-SITA (42 eyes) or FDT (45 eyes), although SAP-FT agreed more closely with FDT (kappa = 0.54 +/- 0.08) on the presence of a visual field defect than did SAP-SITA (kappa = 0.34 +/- 0.08). Correlations of FDT to standard perimetry global indices were similar regardless of the threshold strategy used for standard perimetry, yielding r2= 0.38-0.57 for SAP-FT with FDT, 0.36-0.54 for SAP-SITA with FDT. Despite many similarities of SAP-SITA and SAP-FT, switching the standard of comparison from SAP-FT to SAP-SITA changes the relationship to FDT with regard to visual field abnormality, but not correlations of global indices. FDT detected abnormal fields in more eyes than SAP-FT. SAP-FT tended to detect a subset of eyes found abnormal by FDT. Visual field defects may be detected more often by FDT and SAP-SITA in eyes with early visual field loss, but these two tests may not agree on which eyes show field loss in patients who undergo both tests at follow-up.

Threshold and Variability Properties of Matrix Frequency-Doubling Technology and Standard Automated Perimetry in Glaucoma

To compare test results from second-generation Frequency-Doubling Technology perimetry (FDT2, Humphrey Matrix; Carl-Zeiss Meditec, Dublin, CA) and standard automated perimetry (SAP) in patients with glaucoma. Specifically, to examine the relationship between visual field sensitivity and test-retest variability and to compare total and pattern deviation probability maps between both techniques. Fifteen patients with glaucoma who had early to moderately advanced visual field loss with SAP (mean MD, -4.0 dB; range, +0.2 to -16.1) were enrolled in the study. Patients attended three sessions. During each session, one eye was examined twice with FDT2 (24-2 threshold test) and twice with SAP (Swedish Interactive Threshold Algorithm [SITA] Standard 24-2 test), in random order. We compared threshold values between FDT2 and SAP at test locations with similar visual field coordinates. Test-retest variability, established in terms of test-retest intervals and standard deviations (SDs), was investigated as a function of visual field sensitivity (estimated by baseline threshold and mean threshold, respectively). The magnitude of visual field defects apparent in total and pattern deviation probability maps were compared between both techniques by ordinal scoring. The global visual field indices mean deviation (MD) and pattern standard deviation (PSD) of FDT2 and SAP correlated highly (r > 0.8; P < 0.001). At test locations with high sensitivity (>25 dB with SAP), threshold estimates from FDT2 and SAP exhibited a close, linear relationship, with a slope of approximately 2.0. However, at test locations with lower sensitivity, the relationship was much weaker and ceased to be linear. In comparison with FDT2, SAP showed a slightly larger proportion of test locations with absolute defects (3.0% vs. 2.2% with SAP and FDT2, respectively, P < 0.001). Whereas SAP showed a significant increase in test-retest variability at test locations with lower sensitivity (P < 0.001), there was no relationship between variability and sensitivity with FDT2 (P = 0.46). In comparison with SAP, FDT2 exhibited narrower test-retest intervals at test locations with lower sensitivity (SAP thresholds <25 dB). A comparison of the total and pattern deviation maps between both techniques showed that the total deviation analyses of FDT2 may slightly underestimate the visual field loss apparent with SAP. However, the pattern-deviation maps of both instruments agreed well with each other. The test-retest variability of FDT2 is uniform over the measurement range of the instrument. These properties may provide advantages for the monitoring of patients with glaucoma that should be investigated in longitudinal studies.

Test–Retest Variability of Multifocal Visual Evoked Potential and SITA Standard Perimetry in Glaucoma

To investigate the test-retest variability of multifocal visual evoked potential (mfVEP) and threshold perimetry in glaucoma, and to examine the relationship between the two techniques. Data were recorded using the AccuMap mfVEP and SITA standard program of the Humphrey Field Analyzer. Data were obtained twice within a 4-week period from both eyes of 74 patients with varying amounts of glaucomatous visual field loss. The number of defective test locations (those falling beyond a given probability value of being normal) were calculated for mfVEP and SITA, using databases incorporated within the instruments software. Reliability measures and test times were recorded along with patient test preference. Both tests showed a large degree of test-retest variability in the number of defective test locations (95% limits of agreement for mfVEP and SITA being 13.39 and 9.88, respectively). A "fair to moderate" degree of spatial agreement was found between mfVEP and SITA. The number of mfVEP defective locations was dependent on the signal amplitude. No relationship was found between test-retest variability and the reliability indices for either test. The mean time taken to perform mfVEP and SITA standard was 33 and 20 minutes, respectively, and 73 of the 74 patients preferred the mfVEP test. Test-retest variability was found to be slightly greater for mfVEP. The processing of mfVEP signals needs to be changed to remove the relationship between the number of defective locations and signal amplitude. The majority of patients preferred mfVEP to conventional perimetry although mfVEP takes longer to perform.

Effect of cataract on the results of automated perimetry in glaucoma

Effect of cataract on the results of automated perimetry in glaucoma

Nordic research in ophthalmology.

To provide an overview of some of the current activities in eye research in the Nordic countries. The presentations at the biannual Nordic Congress of Ophthalmology, held in Tampere, Finland in 2002, were reviewed and the contributions found most noteworthy are included in this article along with a limited discussion of each research field. However, space requirements prevented the inclusion of many interesting scientific contributions. Important contributions in various subfields of eye research and ophthalmology are reviewed. These include cornea, cataract, paediatric ophthalmology, glaucoma, diabetic eye disease, age-related macular degeneration, physiology and pharmacology and oncology. Eye research is very active in the Nordic countries and significant contributions are being made to ophthalmology in several fields on a world scale. We hope to continue to review Nordic contributions to eye research after each Nordic Congress of Ophthalmology and plan to make the reviews more systematic and comprehensive in the future.

Learning effect and measurement variability in frequency-doubling technology perimetry in chronic open-angle glaucoma.

To prospectively study the learning effects and measurement variability in frequency-doubling technology perimetry in glaucoma patients who were well practiced in testing with an automated static perimeter. Patients with clinically stable chronic open-angle glaucoma (n = 44) who had undergone repeated perimetric testing using a 30-2 full-threshold program with a Humphrey perimeter with reliable results were enrolled in the study. The authors tested each patient using frequency-doubling technology perimetry. After initial examination with the C-20-1 screening program, the N-30 full-threshold program was performed three times at 1- to 3-month intervals. Perimetric results of the N-30 program improved with repeated testing in both eyes between the first and second visits. The average of mean deviation (MD) of the N-30 program significantly improved by 0.6 dB ( < 0.001) in the right eye and 0.8 dB ( < 0.002) in the left eye between the first and second sessions. The sensitivity in 4 of 19 test points (right eye) and 5 of 19 points (left eye) improved significantly at the second sessions, but not the third session. There were no significant differences in the FDT results between the second and third sessions in both eyes. The standard deviation of the mean MD value for the three sessions ranged from 3.8 to 4.0 dB in both eyes. Baseline measurements for perimetric follow-up with the N-30 full-threshold program in patients with glaucoma should be repeated at least twice after testing with the C-20-1 screening program.

A neural model of perimetry in glaucoma

A neural model of perimetry in glaucoma