Henson 9000: Technical profile

Detect glaucoma with Smart Supra

The newest visual field test on the market, uses the latest research to incorporate 24-2 and 10-2 patterns in a uniquely fast test. The result is increased sensitivity to shallow defects in the central ten degrees of the visual field commonly missed by 24-2 patterns. As a result, Smart Supra is fast. Its 26 point initial phase (sufficient to screen low risk patients) can be completed in under a minute, whilst its 24-2 plus 10-2 test pattern (86 points) takes around 3.5 minutes*. (The same patterns would take closer to 10 minutes to complete on a standard threshold test.) Further details.

Monitor and manage glaucoma with ZATA

For the ongoing management of patients with suspected or diagnosed glaucoma, the Henson 9000 offers the ZATA threshold algorithm and a full suite progression analysis tools. Using the latest research findings to optimise performance, ZATA is uniquely able to use prior patient data to shorten test times and improve the accuracy of results in patients with established loss. Further details.

Put it into practice

We understand that our equipment must fit seamlessly into your practice and processes. We have designed a low maintenance, compact perimeter for flexible positioning with networking facilities available as standard. Our suite of tests and associated analytical techniques give you all the information you need to support the best patient outcomes. Learn more.

Technical specification | NEW product brochureVideos | FAQs

Smart Supra

The best of supra-threshold and threshold perimetry combined

Smart Supra is unique supra-threshold algorithm designed to provide a solution to the 3 main problems affecting visual field tests today…

Smart Supra increases sensitivity to shallow defects in the central ten degrees of the field by using probability-based supra-threshold increments, as opposed to the fixed ones used in standard supra-threshold tests.

The use of probability-based increments means that the supra-threshold increment increases with eccentricity, accounting for the known issue of increased variability at eccentric locations. Including test points from both 24-2 and 10-2 test patterns further increases the likelihood of detecting small central defects that can be missed with the 24-2 test pattern when used in isolation¹.

As a result, Smart Supra is fast. Its 26 point initial phase (sufficient to screen low risk patients) can be completed in under a minute, whilst the 24-2 plus 10-2 test pattern (86 points) takes around 3.5 minutes*. (The same patterns would take closer to 10 minutes to complete on a standard threshold test.)

Download our new Henson 9000 brochure to learn more.

¹ De Moraes CG, Hood DC, Thenappan A, Girkin CA, Medeiros FA, Weinreb RN, Zangwill LM, Liebmann JM. 24-2 Visual Fields Miss Central Defects Shown on 10-2 Tests in Glaucoma Suspects, Ocular Hypertensives, and Early Glaucoma. Ophthalmology. 2017 Oct;124(10):1449-1456.
PMID: 28551166

* Test times are approximations only and will differ according to patient response time and level of loss.

3 problems with current visual field tests for glaucoma

  1. High variability at moderate to severely damaged test locations (<20 dB)² ³ [Fig.1, below]
  2. Poor sensitivity to small central defects when testing with the 24-2 test pattern¹
  3. Long test times only get longer with the inclusion of more test locations
Henson Smart Supra Fig.1
Fig. 1: Test re-test variability at different levels of loss, redrawn from Gardiner [3]

² Henson DB, Chaudry S, Artes PH, Faragher EB, Ansons A. Response variability in the visual field: comparison of optic neuritis, glaucoma, ocular hypertension, and normal eyes. Invest Ophthalmol Vis Sci. 2000 Feb;41(2):417-21.
PubMed PMID: 10670471

³ Gardiner SK, Swanson WH, Goren D, Mansberger SL, Demirel S. Assessment of the reliability of standard automated perimetry in regions of glaucomatous damage. Ophthalmology. 2014 Jul;121(7):1359-69.
PMID: 24629617

3 solutions from Smart Supra

  1. Smart Supra replaces the need to test at locations below 20dB where variability is so high that meaningful measures of threshold are not attainable [Fig.1, above] by setting the threshold increment according to the normal variability found at each location, allowing it to test at levels which have a 95, 98 and 99% probability of being seen [Fig.2, below].
  2. Smart Supra uniquely incorporates a 10-2 test pattern in response to recent research showing that small central defects can be missed by 24-2 field tests¹.
  3. Smart Supra is fast even with three levels of testing. Its easy, in-test extension from 26 points (~1 min.), to 24-2, then 24-2 plus 10-2 (3.5 mins.), as required, allows Smart Supra to test more points in less time.
Henson Smart Supra Fig.2
Fig.2: Test levels based on 95, 98 and 99% probability of being seen by an age-matched eye with no visual field loss

3 reasons to choose to Version 4.0

Smart Supra is only available with Version 4.0 Software for Henson 9000. 

  1. Improved practice efficiency – redesigned interfaces make tests easier to setup, run and save; virtual tree view allows patient records to be found more quickly
  2. New Smart Supra test – uniquely intelligent algorithm enables a 24-2 plus 10-2 test to be done in ~3.5 mins; standard screening test takes less than 1 minute*
  3. Fewer false referrals – minimising admin for high street optometrists, lessening the burden on hospital eye services  and reducing impact on quality of life for patients

Version 4.0 software is included as standard on all Henson 9000s sold from June 2018. It is available as an upgrade for all existing Henson 9000 users. Please contact your local distributor for more information.

ZATA threshold testing

Uniquely patient-centred

For the management of patients with suspected or diagnosed glaucoma, the Henson 9000 offers the ZATA threshold algorithm. ZATA uses the latest research findings to optimise performance and keep test times short. Uniquely, ZATA can use prior test result data (where available) to shorten test times and improve the accuracy of results in patients with established loss. ZATA is defined by

Innovation – prior test values can be used to intelligently vary test criteria for more accurate thresholds
Efficiency – ZATA tests can be completed in ~2.5 minutes per eye
Ease of use – software is easily operable by all levels of optical staff

A brief history of threshold testing

Threshold tests are used when there is a need to accurately measure the depth of any visual field loss.

The first threshold algorithm (Full Threshold) was developed in the 1970s. It was reasonably accurate but took in excess of 10 minutes per eye to perform. A later development (FastPac, Fast Threshold) shortened the test time but was less accurate and as such was not widely adopted. In the 1980/90s a series of papers were published by vision scientists on the more efficient Bayesian approach to obtaining thresholds. One of the algorithms promoted by these researchers (King-Smith 1994) was called ZEST (Zippy Estimate by Sequential Testing). In 1997 a Swedish group of ophthalmologists utilised this work to develop a new perimetric algorithm called SITA (Swedish Interactive Threshold Algorithm). The ZEST algorithm has also been used to develop ZATA (Zippy Adaptive Threshold Algorithm) the threshold test used on the Henson 9000.

An important characteristic of these new algorithms is what is known as their terminating criteria. This specifies how accurate the threshold measure should be. As a general rule the more accurate you want a threshold test to be the longer it will take to perform. The Swedish (SITA) group set their terminating criteria to give an accuracy similar to the 1970s Full Threshold technique (termed SITA Standard), later producing a second version that was faster, but less accurate (SITA Fast). Since the development of SITA a lot more has been learnt about how patients with glaucoma respond to stimuli and the importance of keeping test times down to a minimum. These findings have been used to develop ZATA, the fastest, most accurate threshold test available today.

5 reasons to choose ZATA for glaucoma management

While ZATA is based upon the same principles as SITA it differs in some important ways.

  1. When possible it uses prior data as a starting level. In instances where patients have been tested previously, ZATA will build on this prior data for subsequent tests, rather than starting a new test from age normative data, as is common in other perimeters. This helps negate false positive responses early in a test by patients with established loss and serves to reduce patient anxiety, too, by reducing the number of unseen presentations. It can also speed up test times – benefiting patients and enhancing practice workflow.
  2. ZATA does not just use single terminating criteria. ZATA varies the terminating criteria to give more accurate thresholds at damaged and neighbouring locations. This reduces test times, both for patients with advanced visual fi eld loss and for those with no loss at all.
  3. ZATA uses looser terminating criteria in severely damaged locations (<10 dB) ZATA does not attempt an accurate measurement of thresholds below 10 dB where variability is high and attempts at accurate measures do not yield any useful additional data.
  4. ZATA allows both 24-2 and 30-2 stimulus patterns in a single test. Via a simple ‘extend’ facility operators can extend the 24-2 test pattern to a 30-2 test pattern during or at the end of each test so avoiding the need to retest the 24-2 locations if later opting for a 30-2 test.
  5. ZATA uses the standard printout for universal compatibility. The standard print format is used to aid interpretation and comparison with data from other perimeters. The Henson 9000 software also allows users to switch between multiple views – threshold, grayscale, or defect values – at the end of each test.

Henson 9000: all the tests and tools you need

You have all the tools you need to detect and monitor functional loss with our range of supra-threshold and threshold tests, as well as monitoring the whole visual field with the Esterman binocular driving tests (Groups 1 & 2).

Our Smart Supra results are designed to be compatible with threshold results, whilst our ZATA results include all recognized global indices (mean defect, standard deviation defect, hemifield), plus threshold and grayscale, total deviation and pattern deviation values.

ZATA progression analysis tools display global indices (mean defect and pattern standard deviation) against the age of the patient and the mean defect rate of change displayed with confidence levels.

Threshold data can also be presented on Glaucoma Staging System II. Using both the mean defect and pattern standard deviation is better than using either index in isolation.

The ZATA threshold test includes foveal threshold measurement facility as standard.

Technical specification

Download in PDF

Test specifications
Visual field range (degrees) 60° (monocular) / 160° (binocular)
Visual field testing distance 25 cm
Stimulus intensity (maximum) 10,000 ASB
Background illumination 31.5 ASB
Stimulus duration 200 ms
Stimulus size Goldmann III
Test methods Standard Automated Perimetry (SAP), white-on-white
Screening tests/patterns
Smart Supra – single stimulus 26, 54 and 86 point tests (incorporating both 24-2 and 10-2 test pattern points)
Suprathreshold – multiple stimulus 26, 54 and 86 point tests (incorporating both 24-2 and 10-2 test pattern points)
Esterman (Driving) Groups 1 (120 point) and 2 (124 point) (EU standard)
Customised tests Test locations can be manually added to all Smart Supra tests
Threshold tests/patterns
ZATA Standard – threshold central 10-2; 24/30-2 (extendable in-test)
ZATA Fast – threshold central 10-2; 24/30-2 (extendable in-test)
Average testing times*
Smart Supra – single stimulus ~1 min  (26 points); 3.5 minutes for fully extended 24-2 plus 10-2 test (86 points)
Suprathreshold – multiple stimulus <30 seconds per eye (26 points)
ZATA Standard ~2.5 minutes per eye
ZATA Fast ~2 minutes per eye
Fixation control  
Fixation target Single or 4-point LED diamond pattern
Heiji-Krakau Yes (ZATA)
Video eye monitor Yes
Software features
Patient management database MS Windows compatible; networkable
Practice management integration EMR compatibility (parameter passing and text file)
Hemifield Analysis Yes
Progression Analysis Yes
HFA data import Yes
Languages English, Chinese, French, German, Italian, Japanese, Norwegian, Portuguese, Brazilian Portuguese, Spanish (Peninsula), Spanish (Latin America)
Connectivity
DICOM Yes (images)
Ethernet Yes, via connected computer
Database backup Removable, network or cloud storage
Dimensions
Weight (kg) 13.5
Measures (W x D x H / mm) 440 x 400 x 452
Classification
Mains operated Yes
Medical device Class 1
Applied part Type B
Control device External PC/laptop running MS WindowsTM Professional, v. 7, 8 & 10
Patient unit inputs/outputs C13 mains input; Patient Response Button; 2 x USB Type B connector
Electrical requirements 85 – 263Vac, 50/60Hz, 60VA
Optional printer Any compatible with controlling computer

* Test times are approximations only and will differ according to patient response time and level of loss.

Henson 9000 video library

The structure/function relationship in glaucoma and recent developments in functional measures

Professor Henson presents on the importance of structural and functional techniques in detecting and managing glaucoma and explains why his new Smart Supra visual field test is a significant step forward in glaucoma detection and management.

Video length: 46:00

Screening with Henson perimeters

Professor David Henson explains how screening works on Henson perimeters.

Video length: 11:25

Henson screening test patterns

Professor Henson explains the test patterns available on the Henson 7000 and Henson 8000. (The Henson 8000 has now been superseded by the Henson 9000 which has the same three  suprathreshold screening patterns – 26, 68 and 136.)

Video length: 0:54 secs

Multiple stimulus tests and their benefits

Professor David Henson explains the rationale for the faster, more precise and “patient-friendly” multiple stimuli test and how this differs from single stimulus testing.

Video length: 5:40

ZATA vs. other threshold tests

Professor David Henson explains the similarities and differences between his ZATA threshold algorithm and others available.

Video length: 11:33

HFA compatibility

Professor David Henson explains the ways in which the Henson 9000 and its ZATA algorithm are compatible with the Humphrey. (Please note, the 8000 model referred to in the video has now been superseded by the Henson 9000.)

Video length: 1:55

The Hensons and practice management integration

Professor David Henson explains that the Henson software has a patient database that can be easily incorporated in practice management systems.

Video length: 3:33

Frequently asked questions

Which is more important sensitivity or specificity?

  • 100% sensitivity = every screening test would capture those with a visual field defect, i.e. result = fail
  • 100% specificity = every screening test would not fail those with a healthy visual field, i.e. result = pass

Ideally, a screening test would be 100% sensitive and 100% specific, but in reality there will always be anomalies – i.e. ‘false negatives’ (those with the condition who pass the test) and ‘false positives’ (those without the condition who fail the test).

The sensitivity/specificity of a visual field screening test can be altered by changing the fail criteria, e.g. if the fail criteria of a supra-threshold visual field test were to be changed from a single missed point to a cluster of three missed points, then the sensitivity would go down and the specificity would go up.

So, which is the more important? To answer this question you have to answer another. What are the relative costs of a false positive and false negative? When screening for glaucoma in an unselected population, where the prevalence of the disease is low (<2%), it is generally accepted that the specificity should be ≥95%. If it falls much below this figure then we end up failing a relatively large number of people that do not have the disease. If the study population is a high risk one (higher percentage of true cases) then the sensitivity should be increased at the cost of lowered specificity.

How can I screen with the Henson 9000?

There are 2 ways in which you can screen the visual field with the Henson 9000.

You can use the fast and accurate supra-threshold strategies (Smart Supra on Version 4.0 software), with a choice of single or multiple stimulus presentations for additional flexibility, or the rigorous and detailed ZATA threshold test.

Screening with the supra-threshold strategies is certainly the fastest option but the testing times of ZATA, compared to other threshold algorithms, make it feasible to offer a threshold strategy by default as a form of enhanced screening test.

How long does a ZATA threshold test take?

The length of a ZATA test will be determined by the extent of a patient’s field loss.

  • A normal patient with no field loss will complete the test in approximately 2.5 minutes (with average response times)
  • A patient with significant field loss tested from previously stored data will likely complete the test in under 4 minutes due to the ZATA test’s variable termination criteria.
  • A patient with moderate field loss, or one who has no prior data stored, will take approximately 4-5 minutes per eye to complete the test.

How does the ZATA test differ from standard full threshold?

ZATA was developed to counter all of the problems associated with testing patients with field loss on a full threshold type test. It runs the 24/2 test pattern but uses supra- as well as full threshold testing with different terminating criteria. Furthermore, it uses data from surrounding points as well as prior data (if available).

All of these strategies combine to make ZATA an easier test for patients to perform while offering the same level of accuracy as a standard full threshold would in monitoring glaucoma progression.

How does the ZATA algorithm differ from SITA?

The ZATA algorithm is able to make use of prior patient data. If the Henson database contains a record for a previous threshold test then ZATA uploads the previous threshold measures to use as starting values for the new test. This reduces test times and improves accuracy.

Nor does ZATA use a fixed terminating criteria. In areas of severe loss, where thresholds estimates are very variable, and at locations near to normal values, it uses looser terminating criteria, reserving more accurate measures for locations where there is existing mild damage. This again speeds up test times by focusing on locations where change is expected to occur.

In other ways ZATA and SITA are similar. They both use the same test patterns (24/30-2). The threshold values are compatible as are the global indices.

Can the Henson 9000 test a patient's peripheral isopter?

All Hensons are static only perimeters. Isopters require kinetic testing, i.e. a stimulus that moves across the visual field. Kinetic perimetry is only available on selected HFA and Octopus perimeters.

The Henson 9000 performs static determination within the central 30° and qualitative automated threshold perimetry, including the 30-2 and 24-2 patterns of test locations. It is very fast, although exact test times are dependent upon the number of test locations and the type of visual field loss.

In a recent as yet unpublished project with 17 patients, the test time for a 24-2 ZATA Standard test with a superior arcuate defect was 3:01 mins, compared to 7:45 for a Full Threshold test with the same patient sample.

Is the Henson Esterman test DVLA Compliant?

The Henson Esterman test is approved for testing Group 1 and Group 2 drivers.

Can the 9000 be operated from any PC?

Yes, it can be operated from any PC running the MS Windows™ Professional operating system (version 7, or above).

The control device must also have two spare USB ports for interfacing with the Henson 9000.

Is the software easy to install?

Yes. The software is supplied on a USB memory stick and is a single file installer. Simply click on it and it will install all parts of the software.

Both Henson machines are supplied with a quick start guide that takes you through the whole process step-by-step.

Why do I get an “internal error has occurred” message when trying to save even though I can see the record has saved in the database?

This relates to a problem with the settings for your backup.

Firstly, check the location of the backup allows files to be created. If it has been set to a read-only drive, or one that is protected by Windows, then the record will save in the database successfully but the backup will fail – hence the error message you are receiving.

Such read-only locations may be: the root of the C drive; a fundus camera (these often show up in Windows as USB flash drives); a Windows system folder or a mapped drive on a computer that is not switched on.

To ensure a successful backup set the location to a mapped network drive on your PC or a removable hard drive/USB flash drive.

Can I use any printer with the Henson software?

Yes.

The Henson software prints the test result to the default installed printer on the laptop/computer being used as the control device. Printing is done via the default installed PDF viewer (Adobe Reader in the case of Henson 8000). Essentially, as long as the installed printer is Windows-compatible it will work without a problem.