Changes of glaucomatous field defects. Degree of accuracy of measurements with the automatic perimeter Octopus

Reliability of Visual Field Testing in a Telehealth Setting Using a Head-Mounted Device: A Pilot Study

PRCIS

Monitoring visual fields (VFs) through virtual reality devices proved to have good inter-test and test-retest reliability, as well as easy usability, when self-administered by individuals with and without VF defects in a remote setting.

PURPOSE

To assess the reliability of remote, self-administered VF monitoring using a virtual reality VF (VRVF) device in individuals without ocular disease and with stable VF defects.

MATERIALS AND METHODS

Individuals without ocular disease and with stable defects were recruited. All participants had a baseline standard automated perimetry (SAP) test. Participants tested remotely on a VRVF device for 4 weeks (examinations V 1 , V 2 , V 3 , and V 4 ), with the last 3 unassisted. The mean sensitivities of VRVF results were compared with each other and to SAP results for reliability.

RESULTS

A total of 42 eyes from 21 participants were tested on the VRVF device. Participants tested consistently although external factors impacted outcomes. VRVF results were in reasonable agreement with the baseline SAP. Examinations performed by the cohort with stable defects evinced better agreement with SAP examinations (V2, P = 0.79; V3, P = 0.39; V4, P = 0.35) than those reported by the cohort without ocular disease (V2, P = 0.02; V3, P = 0.15; V4, P = 0.22), where the null hypothesis is that the instruments agree. Fixation losses were high and variable in VRVF examinations compared with those of SAP, particularly in certain test takers. Participants considered the device comfortable and easy to use.

CONCLUSIONS

Self-administered, remote VF tests on a VRVF device showed satisfactory test-retest reliability, good inter-test agreement with SAP, and acceptability by its users. External factors may impact at-home testing and age and visual impairment may hinder fixation. Future studies to expand the sample size and understand inconsistencies in fixation losses are recommended.

A New SITA Perimetric Threshold Testing Algorithm: Construction and a Multicenter Clinical Study

PURPOSE

To describe a new time-saving threshold visual field-testing strategy-Swedish Interactive Thresholding Algorithm (SITA) Faster, which is intended to replace SITA Fast-and to report on a clinical evaluation of this new strategy.

DESIGN

Description and validity analysis for modifications applied to SITA Fast.

METHODS

Five centers tested 1 eye of each of 126 glaucoma and glaucoma suspect patients with SITA Faster, SITA Fast, and SITA Standard at each of 2 visits. Outcomes included test time, mean deviation, and the visual field index (VFI), significant test points in probability maps, and intertest threshold variability.

RESULTS

Mean (standard deviation) test times were 171.9 (45.3) seconds for SITA Faster, 247.0 (56.7) for SITA Fast, and 369.5 (64.5) for SITA Standard (P < .001). SITA Faster test times averaged 30.4 % shorter than SITA Fast and 53.5 % shorter than SITA Standard. Mean deviation was similar among all 3 tests.VFI did not differ between SITA Fast and SITA Faster tests, mean difference 0%, but VFI values were 1.2% lower with SITA Standard compared to both SITA Fast (P = .007) and SITA Faster (P = .002). A similar trend was seen with a slightly higher number of significant test points with SITA Standard than with SITA Fast and SITA Faster. All 3 tests had similar test-retest variability over the entire range of threshold values.

CONCLUSIONS

SITA Faster saved considerable test time. SITA Faster and SITA Fast gave almost identical results. There were small differences between SITA Faster and SITA Standard, of the same character as previously shown for SITA Fast vs SITA Standard.

Detecting the progression of normal tension glaucoma: a comparison of perimetry, optic coherence tomography, and Heidelberg retinal tomography

Purpose

We compared the abilities of Stratus optical coherence tomography (OCT), Heidelberg retinal tomography (HRT) and standard automated perimetry (SAP) to detect the progression of normal tension glaucoma (NTG) in patients whose eyes displayed localized retinal nerve fiber layer (RNFL) defect enlargements.

Methods

One hundred four NTG patients were selected who met the selection criteria: a localized RNFL defect visible on red-free fundus photography, a minimum of five years of follow-up, and a minimum of five reliable SAP, Stratus OCT and HRT tests. Tests which detected progression at any visit during the 5-year follow-up were identified, and patients were further classified according to the state of the glaucoma using the mean deviation (MD) of SAP. For each test, the overall rates of change were calculated for parameters that differed significantly between patients with and without NTG progression.

Results

Forty-seven (45%) out of 104 eyes displayed progression that could be detected by red-free fundus photography. Progression was detected in 27 (57%) eyes using SAP, 19 (40%) eyes using OCT, and 17 (36%) eyes using HRT. In early NTG, SAP detected progression in 44% of eyes, and this increased to 70% in advanced NTG. In contrast, OCT and HRT detected progression in 50 and 7% of eyes during early NTG, but only 30 and 0% of eyes in advanced NTG, respectively. Among several parameters, the rates of change that differed significantly between patients with and without progression were the MD of SAP (p = 0.013), and the inferior RNFL thickness (p = 0.041) and average RNFL thickness (p = 0.032) determined by OCT.

Conclusions

SAP had a higher detection rate of NTG progression than other tests, especially in patients with advanced glaucoma, when we defined progression as the enlargement of a localized RNFL defect. The rates of change of the MD of SAP, inferior RNFL thickness, and average RNFL thickness differed between NTG patients with and without progression.

A strategy for averaged estimates of visual field threshold: spark

PURPOSE

The purpose of this work is to design a rapid perimetric strategy to provide averaged results.

METHODS

We designed a simulation examination model using the distribution frequency of local deviations or defects, based on a retrospective study of 90,335 examinations performed in a glaucoma department.

RESULTS

Threshold deviation from normal age-adjusted values of 6 points representative of the main areas of glaucomatous visual field allowed estimating the real mean deviation (MD) with a correlation coefficient r=0.995 (SE=0.71 dB) when original values were used, and r=0.984 (SE=1.26 dB) when values from a rapid simulated test model were used. SE of the local deviations (average=3.06 dB) was close to usual mean threshold fluctuation in patients with different degrees of defect. In patients with early glaucoma (MD<6 dB) the SE of the estimated MD was <0.9 dB and the SE in estimating the local point-to-point deviations was 1.8 dB. We included 3 additional phases to obtain 3 additional results and a final averaged result. For the average and median of the 4 phases, the SE of MD ranged from 0.4 to 0.5 dB for the whole sample and from 0.3 to 0.4 in early glaucoma. Local deviation SE was close to 2 dB in the whole sample and between 1.2 and 1.5 dB in early glaucoma.

CONCLUSIONS

Bearing in mind threshold fluctuation, the strategy allows for several possible outcomes, and provides averaged and theoretically more stable results.

Oculus-Spark perimetry compared with 3 procedures of glaucoma morphologic analysis (GDx, HRT, and OCT)

PURPOSE

To compare diagnostic capabilities and agreement between Oculus-Spark perimetry and 3 procedures of glaucoma morphologic analysis.

METHODS

A total of 102 normal eyes and 104 consecutive eyes with suspected or confirmed glaucoma (1 eye per subject) were analyzed in a prospective observational case-control study, using Spark strategy (Oculus Easyfield Perimeter), Heidelberg retinal tomograph (HRT), Zeiss laser polarimetry (GDx), and Cirrus optical coherence tomography (OCT).

RESULTS

Spark first phase lasted 37 seconds and all 4 phases 2:34 minutes. Specificities and sensitivities were as follows: Spark mean deviation (MD) first phase (95.1%, 85.6%), MD second and final phases (95.1%, 86.5%), GDx-nerve fiber indicator (95.1%, 57.4%), HRT-Reinhard Burk discriminant function (95.1%, 52.9%), HRT glaucoma probability score (95.1%, 71.2%), Cirrus OCT vertical cup/disc ratio (96.1%, 85.6%), and Cirrus OCT retinal nerve fiber layer thickness (95.1%, 68.0%). Diagnostic agreement between second and final Spark MD phases was kappa=0.92; between phase 1 Spark/MD and Cirrus OCT/vertical C/D ratio was kappa=0.78. Agreements between the 2 Cirrus OCT indices was kappa=0.69 and between the 2 HRT indices was kappa=0.559. The correlation coefficient between second and final MD and PSD was 0.99, and 0.98 between the number of scotomatous points. There was high concordance in scotoma position in both phases (kappa=0.86). The linear correlation coefficients between the morphologic indices were 0.48-0.78, and between morphologic and functional indices 0.51-0.76. Correlation coefficients comparing morphologic and functional indices were similar in the first and the last phase (p>0.05 in all cases).

CONCLUSIONS

Spark perimetry appears to show useful sensitivity and specificity, even in the first phase, and good agreement with the morphology.

The use of the G1 and Octosmart programs in detecting temporal changes in the visual field

PURPOSE

The Octopus program Octosmart is able to classify visual fields into six classes. In the program a horizontal bar indicates these classes, and an indicator points to the most probable position, related to the measured pathology. The width of this dashed indicator shows the range of possible fluctuations in the measurement and, therefore, its precision. This study sets out to analyse the suitability of this display mode using other visual-field index data.

METHODS

The visual fields of 83 glaucomatous eyes of 61 patients of various etiological groups and glaucoma suspects were studied for periods varying from 1 to 5 years in a retrospective study. All examinations were performed with the G1 Octopus program and analyzed with the Octosmart program. The statistical significance of linear trends of the visual-field indices, mean defect (MD) and corrected loss variance (CLV), and the class shown by the indicator (POI = position of indicator) were determined, and their regression coefficients were analyzed by means of a linear trend test as a function of time.

RESULTS

Of the sample of 83 tested eyes, a total of 18 significant trends were recorded after five examinations. All visual-field indices showed a trend towards amelioration.

CONCLUSIONS

The 18 significant trends observed must be attributed to perturbing long-term fluctuations and, despite their statistical significance, are of little clinical value. It is questionable whether an increased number of examinations per eye would have attenuated the threshold fluctuations sufficiently to make the change in field class more reliable.

Effects of pupillary dilation on automated perimetry in glaucoma patients receiving pilocarpine

The authors studied 18 glaucoma patients receiving pilocarpine 2% therapy with automated static threshold perimetry using the Humphrey Field Analyzer 30-2 and STATPAC programs before and after instillation of 10% phenylephrine. The mean defect improved by an average of 3.14 decibels (dB) (standard deviation, 1.89 dB0 after administration of phenylephrine (P less than 0.001). The pattern standard deviation and the corrected pattern standard deviation also improved with dilation by 1.42 dB (P less than 0.01) and 1.73 dB (P less than 0.05), respectively, after dilation with phenylephrine. Comparisons of the unweighted means of threshold values in three zones of increasing eccentricity showed that the outer zone of the visual field had the greatest improvement after dilation. These findings indicate that pupillary dilation in glaucoma patients receiving pilocarpine therapy produces a nonuniform increase in threshold sensitivities and support the importance of consistent pupillary diameters on serial automated visual field examinations.

Effects of pupillary constriction on automated perimetry in normal eyes

The authors studied the effects of pupillary constriction (pilocarpine 2%) on automated static threshold perimetry in 20 normal subjects using the Humphrey Field Analyzer 30-2 and STATPAC programs. The mean defect (MD) worsened by an average of 0.67 decibels (dB) (standard deviation, 0.67 dB) in constricted fields compared with baseline visual fields (P less than or equal to 0.001). Independent comparisons of the unweighted means of threshold values for the central 30 degrees, 24 degrees, and 10 degrees were also done and showed significant reductions in sensitivity after constriction (P less than or equal to 0.001). These findings indicate that changes in pupillary diameter may produce significant declines in threshold sensitivities and support the importance of consistent pupillary diameters on serial automated visual field examinations.

Quantitative office perimetry

This study presents a preliminary comparison of six commercially-available automated threshold static parameters, consisting of three projection perimeters (Humphrey Field Analyzer, Squid, and Octopus 500) and three light-emitting diode (LED) perimeters (Dicon 2000, Fieldmaster 50, and Digilab 350). Eighteen individuals were included in the study: 6 normal observers (31-58 years old), six patients with glaucomatous field loss in both eyes (55-70 years old), and six patients with neuro-ophthalmologic or retinal visual field abnormalities in both eyes (12-61 years old). Three aspects of quantitative testing were evaluated: (1) the patients' and normal observers' acceptance and subjective impressions of the test procedure; (2) the technician's ease of operating the device and related tasks; and (3) practitioner-oriented considerations such as test-retest reliability, comparability of test results and testing time. Our results showed that no device was clearly superior to the others in all respects. Patients were most favorably impressed with the Octopus 500, Squid, and the Fieldmaster 50, while technician impressions were most favorable to the Humphrey Field Analyzer and the Squid. The projection perimeters (Humphrey Field Analyzer, Squid, and Octopus 500) were the easiest to perform cross-comparisons of test results, although there was considerable variation in the clarity of data interpretation from one case to another. Test-retest reliability and the time of testing varied among the six automated perimeters.

The prognosis of glaucoma investigated with computerized perimetry

The efficacy of glaucoma therapy in preventing progression of glaucomatous field loss was investigated in a retrospective study. Hundred eyes with glaucomatous field defects of 71 patients were enrolled in the study. The mean observation period was 3.8 years. The evaluation of potential visual field changes was made with the biostatistical program Delta of the Octopus computerized perimeter. All field examinations were done with the same automated perimeter (Octopus, model 201). In 19% of the eyes adequate medical or surgical therapy failed to arrest the disease process. Improvement or deterioration of the whole field can be simulated by changes of the pupillary diameter, whereas deterioration in the pathologic area only is highly specific for progression of the glaucomatous process.

Variation in visual field measurements with an automated perimeter

Using the Octopus automated perimeter, we conducted visual measurements on four separate occasions during a four-week period in six subjects with normal eyes. In 11 of 12 eyes, we found at least one point at which the threshold for light detection determined for that point showed a variance of more than 4 dB between tests. Thus, automated visual fields must be interpreted cautiously because an apparent pathologic change may only represent normal variation.

Comparative material on automated and semiautomated perimeters-1983

In reviewing all the responses from the private practitioners and clinicians in Departments of Ophthalmology throughout the United States and Canada, it would appear that the majority of individuals are quite happy with the automated perimeters they have purchased. Clinicians should be aware that this is a rapidly changing field and several devices which were previously available are no longer being manufactured. In addition, because of the competition which has recently developed in the automated perimetry industry, prices are continuing to come down. Some practitioners have been unhappy with the fact they paid a higher price for a device which is currently selling at a lower price. However, a similar phenomenon has happened in the computer world and is to be expected as competition increases. The major problems which seem to be of concern to all ophthalmologists, are the difficulty in interpreting data and the management of the data. We believe one of the major frustrations of all practitioners using automated perimeters relates to the fact that this is a totally new technique, which requires time and practice to gain familiarity. In general, it would appear that most of the practitioners have been happy with the service provided by various companies, although there are a few exceptions. Read the enclosed responses and develop your own conclusions. We hope you find the information useful.

Programs SARGON and DELTA: two new principles for the automated analysis of the visual field

The new Octopus programs SARGON and DELTA are described. The SARGON program makes possible the arbitrary distribution of a maximum number of 66 test locations with a resolution of up to 0.2 degrees across the 60 degrees visual field. Eighty user-defined self-created programs can be permanently stored and recalled later at will from the program diskette.. The program DELTA evaluates perimetric examination results with the aid of a series of statistical tests and investigates whether the data base is sufficient to assume a significant deviation, or alternatively, whether a visual field defect can be explained simply by spontaneous fluctuations or if a true pathologic defect should be assumed at a particular level of significance. Furthermore, the program tests changes in the visual field as a function of time for their statistical significance.