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Centerfield® 2

Perimeter

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  • Software
  • SPARK
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OCULUS Centerfield® 2

Thanks to its ergonomic design, user-friendly program navigation and ease of operation, the Centerfield® 2 Perimeter has proven itself to be an invaluable instrument in the Occupational Health area. The unit performs static perimetry up to 70° eccentricity. It also meets the requirements of the German Ophthalmological Society’s (DOG) Road Traffic Commission for conducting visual field testing in accordance with the regulations for the issuance of driver’s licenses and the Guidelines G25 and G41 issued by the German Institute for Occupational Health and Safety.

OCULUS Centerfield® 2 - Kompaktes Perimeter zur Gesichtsfeldprüfung

Functions

Ergonomic Design

The self-contained design and light-shielded viewer allow examinations to be conducted in normally lit rooms. Its robustness and light weight make the Centerfield® 2 perimeter the ideal unit for portable use, which is often a necessity in the Occupational Health area.

Reliable Results

The results of the perimetric measurements are summarized in a clearly structured printout. Areas of abnormality can be quickly recognized and re-examination of these areas independent of the test point grid gives the diagnostic analysis even greater reliability.

Modern Connectivity

The Centerfield® 2 perimeter can be operated via the USB port of a notebook or PC. Together with the supplied device software, this modern solution allows you to fully utilize all of the benefits of today’s IT systems, especially the network connectivity. This guarantees both safe storage of examination data and quick access to that data when needed.

The Examination Programs

The recommended series of pre-defined test programs provided for Centerfield® 2 perimeter covers the examinations most frequently needed in practice. The “Driver’s License Regulations“ program permits occupational and company physicians to test the field of vision in accordance with applicable German regulations (FEV and amendments thereto) governing the issuance of driver’s licenses. The macula and glaucoma programs allow early detection of various retinal diseases.

The OCULUS Test Strategies

Threshold related – suprathreshold strategies have proven to be time-saving and efficient examination methods. The Centerfield® 2 perimeter uses these strategies for all screening programs, including the Driver’s License eye exams. A variety of threshold testing strategies are available for measurement of the exact numeric values of the visual thresholds.

The OCULUS Test Point Grid

The patented projection method allows you to freely select test point grids on the Centerfield® 2. The central field of vision can be examined using functionally or orthogonally distributed test points. Grids such as the “FeV70” or “Esterman” are used for the periphery. This unlimited flexibility enables test grids to be modified if necessary.

Software

Perimetry-Software

Threshold Noiseless Trend (TNT) Progression Analysis
SPARK threshold strategy
Glaucoma Staging Program (GSP)
TNT provides a quantitative, statistical analysis of the visual field examinations conducted over time. For follow-up purposes the software uses all visual field results taken over the entire observation period and takes the patient's threshold values into account obtained on the 30-2, 30x24 or 24-2 patterns. TNT uses a specific filter to reduce the fluctuation range of the threshold values and to perform a consistent trend analysis. In conjunction with the fast SPARK strategy, the sensitivity of detecting progression in early stage glaucoma is greatly improved.

  • TNT creates a concise progression analysis report containing the most important parameters (MD increase, p-values, etc.).
  • TNT can differentiate between diffuse and focal progression based on the focality index (FI) value.
  • TNT applies multiple statistical criteria to establish possible progression.
  • TNT displays the prognosis of the expected visual field for a patient age-group selected by the examiner.

The SPARK examination strategy was primarily developed for glaucoma patients and is available for all OCULUS perimeters. It is based on data from more than 90 000 perimetric findings and allows a very fast, yet very precise measurement of thresholds in the central visual field. The modular structure of the method makes it suitable for a variety of applications:

  • SPARK Precision (optional software) is the full version of SPARK. The complete visual field examination of glaucoma patients takes only 3 minutes per eye. The greater stability of the results allows for more sensitive progression analysis.
  • SPARK Quick is used for follow-up or screening examinations. The test takes just 90 seconds per eye.
  • SPARK Training is ideal for patient training. The 40 second measurement can also be used as a screening examination.

The Glaucoma Staging Program (GSP) is based on pattern recognition and is dedicated to early detection of glaucoma.

The GSP software places examination findings into visual field classes (normal, glaucomatous, artifactual and neuro) based solely on their appearance. In addition, risk classes (normal, suspect, pre-perimetric, early stage, moderate and severe) are also assigned to findings that are classified as normal or glaucomatous. The evaluation results are presented in intuitive green-yellow-red color coding.

The striking novelty of the GSP is its ability to detect subtle changes in the visual field associated with early stage glaucoma. Findings of suspect and pre-perimetric risk classes may contain reductions in the visual field that cannot be readily seen by the examiner. They usually remain undetected also by standard perimetric indices.

The Glaucoma Likelihood Index (GLI) summarizes the results of the GSP classification into a single parameter presenting a value between 0 (normal) and 5 (severe glaucoma).

The Glaucoma Staging Program (GSP) is available for OCULUS Twinfield® 2, Centerfield® 2 and Easyfield® perimeters. This upgrade is available for the existing units.

Device
Threshold Noiseless Trend (TNT) Progression Analysis  SPARK threshold strategy Glaucoma Staging Program (GSP)

Title

Description

FAQ

There are four models in the OCULUS perimeter range. All four models can perform screening (supra-threshold) and threshold perimetry. Apart from being various sizes they differ as follows:

Model Easyfield® Smartfield Centerfield® Twinfield®
Maximum Eccentricity 30° 30°/25°
With fixation shift: 60°/50°
36°
With fixation shift: 70°
90°
Goldmann stimulus size III III III I, III & V
Static/Kinetic Static Static Static/Kinetic Static/Kinetic
Color perimetry White-white White-white White-white
Blue-yellow
White-white
Blue-yellow
Red-white
Stimulus presentation Light emitting diodes (LED) LCD display Back surface projection Back surface projection
All commercially available perimeters make use of the same basic testing principles. What makes one perimeter different to another is the way it performs fast thresholding test. Various fast threshold strategies are included in the OCULUS perimeters, one of which is the SPARK strategy – currently the fastest OCULUS strategy for glaucoma patients. It is the product of many years of research dedicated to obtaining reliable averaged results within the shortest possible time.

Furthermore all the perimeters include a unique glaucoma staging display called the Glaucoma Staging Program (GSP).

Lastly glaucoma progression is monitored by the Threshold Noiseless Trend (TNT) analysis method. The method can distinguish between diffuse or focal progression, and unlike methods based on event analysis, trend analyses make full use of the data pool of earlier examinations.

Yes, it may differ somewhat in appearance, but all the essential data known from other perimeters is available on the OCULUS perimeter printouts.
  • Full Threshold (4-2 dB Staircase) Strategy – the algorithm of this strategy can easily be implemented in any instrument and therefore it is available on most commercial perimeters. Results obtained with this strategy can be compared to results from any other perimeter using the same strategy.
  • OCULUS Fast Threshold Strategy – this strategy aims to reduce test time of the 4-2 dB Staircase strategy. The idea of the OCULUS Fast Threshold Strategy is to achieve a compensating gain in information by starting the measurement at each test point with a luminance value equal to the expected sensitivity value at that point. This expected value is calculated on the basis of measurement results already obtained at neighbouring test points.
  • CLIP (Continuous Light Increment Perimetry) Strategy – locations are tested individually by increasing the luminance of the stimulus continuously until the patient responds.
  • SPARK – the examination is performed in four phases. Each of these phases supplies a possible estimation of the functioning of the entire visual field, and the final result is obtained by averaging of the values obtained during each phase.

Yes. SPARK Precision is performed in four phases over a time period of three minutes. Each of the 66 points in the test pattern will be tested at least once during the three minutes.

Shorter examination time and better repeatability are the main benefits of SPARK. Testing time for this strategy will not exceed three minutes and this holds true even for patients with severely impaired visual field function. Compared to other known strategies, SPARK results have a much lower variability.

Various quick screening methods are available. Normally supra-threshold tests are used, however SPARK Quick has been designed specifically with screening in mind. The duration of the test is 1.5 minutes (90 seconds) on all patients and threshold values are generated after the examination.

Most perimeters only have Heijl-Krakau method to monitor patient fixation. This method uses the blind spot as reference. Glaucoma can cause absolute defects in the vicinity of the blind spot, which may increase as the disease progresses. Using the Heijl-Krakau method for these patients may be problematic. Central fixation control – only available in the OCULUS perimeters – uses the central luminance threshold as reference. This is a helpful method to control fixation for glaucoma patients.

All OCULUS perimeters allow for manual set-up of programs. When comparing current results from an OCULUS perimeter with previous results from other perimeters it is important to adapt the parameters of the current examination as closely as possible to those of the earlier examinations. This needs to be done in order to achieve the highest degree of comparability.

Examinations on the Easyfield®, Smartfield or Centerfield® can be performed in a normally lit room, provided the lighting is diffuse and there are no powerful light sources in the patient’s back. The Twinfield® requires a darkroom, as its perimetric hemisphere must be free of shadows.

GSP uses pattern recognition algorithms in order to assess the visual field results of the patient. For “Normal” and “Glaucomatous” visual fields a risk class can be determined by comparing the detected patterns to the visual field patterns stored in the database of the GSP. If the “Pre-perimetric” risk class dominates the bar chart, it means that the pattern of the measured visual field is similar predominantly to the patterns of patients with pre-perimetric glaucoma from the database. Pre-perimetric glaucoma is defined through glaucomatous changes to the optic nerve head and/or the retinal nerve fibre layer without detectable visual field losses. A “Pre-perimetric” result should be followed by a closer monitoring of the patient.

The software automatically chooses exams done with the same test pattern and the same strategy making comparison fast and easy to detect progression. Exams showing obvious learning effects are excluded by the software. The operator can also manually exclude exams if needed.

Technical Data

Specifications

Programs Pre-defined glaucoma, macula, neurological and screening tests; user-defined tests
Strategies Threshold strategies: OCULUS Fast Threshold, Full Threshold (4-2), CLIP
Optional: SPARK strategy
Age-adapted supra-threshold screening (2-zone, 3-zone, quantify defects)
Test patterns Orthogonal patterns (30-2, 24-2, 30 x 24, 10-2)
Physiological patterns (Area 1-8), Esterman, Profile, customised patterns
Stimulus size Goldmann III
Stimulus color White / Blue
Stimulus duration 200 ms / User-defined
Examination speed Adaptive / Slow / Normal / Fast / User-defined
Stimulus luminance range 0 – 318 cd/m² (0 – 1 000 asb)
Background luminance 10 cd/m² (31.4 asb)
Background colors White / Yellow
Maximum eccentricity 36° / 70° (with fixation shift)
Fixation control CMOS camera, through central threshold, Heijl-Krakau (over blind spot)
Reports Glaucoma Staging Program (GSP),
Progression report for Threshold Noiseless Trend (TNT)
Kinetic Perimetry Strategies: Automated tests along meridians with freely selectable density up to 35°
Stimulus speed: 2°/ s (Goldmann-Standard) or user-defined
Features

Bowl radius r = 11.8 in
Patient positioning Depth-adjustable headrest, optional motorised chinrest
Weight 25.8 lbs; chinrest: 2.4 lbs
Operating voltage 100 – 240 V
Operating system Windows® XP or above
Interface USB
Included in delivery Cover, Lens holder for trial lenses, Opaque occluder, Four trial lenses: ± 1.0 sph. and ± 3.0 sph.

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