PROGRESSOR
IP in PROGRESSOR
The IP in PROGRESSOR is owned by the Institute of Ophthalmology (part of University College London) and Moorfields Eye Hospital NHS Foundation Trust. Medisoft markets PROGRESSOR on behalf of the owners of the product.
PROGRESSOR
The detection and quantification of change in visual fields is one of the most important and problematic areas of glaucoma management. An early, accurate measure of whether a field series shows progressive damage is essential: significant deterioration is likely to prompt a change in treatment, whereas confirmed stability provides more convincing reassurance than lowered intraocular pressure (IOP) alone that therapy is successful.
PROGRESSOR is a software package which analyses visual field progression using pointwise linear regression of sensitivity on time. The pointwise linear model has been demonstrated to provide a valid framework for detecting and forecasting glaucomatous loss. PROGRESSOR produces a cumulative graphical output as shown below.
Each test location is shown as
a bar graph in which each bar represents
one test. The length of the bar relates to
the depth of the defect (longer bars represent
lower sensitivities) and the colour of the
bar relates to the p value of the regression
slope. Thus undamaged locations are seen
as series of short grey bars,
damaged but stable locations are seen as long series of long grey bars,
and progressing locations are
seen as series of progressively
lengthening bars which change colour as the regression
slope becomes more significant.
PROGRESSOR has been compared directly with Statpac 2, the 'native' statistical Glaucoma Change Probability software available as an add-on for the Humphrey Field Analyzer, in terms of ability to detect visual field deterioration. PROGRESSOR was consistently superior in terms of the speed of detection (Viswanathan AC, Fitzke FW, Hitchings RA. Early Detection of Visual Field Progression in Glaucoma: A Comparison of PROGRESSOR and Statpac 2. Br J Ophthalmol 1997;81(12):1037-1042.).
PROGRESSOR has many other features, including those described
below.
Status bar information
As the mouse cursor is moved over the cumulative graphical display, the information shown in the status bar changes from the default "for Help, press F1" to show information about the test location to which the cursor is moved. Sensitivity in decibels, rate of change of sensitivity (slope of the regression line) and the p-value of the regression line are shown. These data relate to the most recent test for the location under consideration unless a subset of dates are being analysed (see below).
Magnification
magnified, detailed image of the cumulative
bar graph at any test location may be
viewed using the 'click and drag' technique
familiar to Windows users. An example of the results of this
process is shown below.
Cumulative graphical display after magnification
of a central test location.
Progressing points
As already shown on page 1, test locations which satisfy progression criteria may be highlighted in red. It is possible to specify progression criteria within a wide range of values for both regression slope and p-value for both inner (non-edge) and edge points. The dialog box used to control progression criteria is shown below.
Progression criteria dialog box.
Subset analysis
By default, all the visual field test
results from both eyes of a subject are
analysed by PROGRESSOR. However, any
subset of tests may be readily
analysed by means of the dialog box shown below. This may
be useful for re-analysing results when other clinical parameters
change, for example before and
after surgery. It may also be used to exclude test results
which are regarded as outliers.
Date selection dialog box.
The dates of tests from each eye required for inclusion
in the sub-analysis are selected and then the Reanalyze button
is clicked. To return the program to a full analysis of all
field tests from both eyes, the Restore button is clicked.
Progression indices
For any selected tests, summary measures of progression status may be displayed as shown below. These consist of the number of progressing points which satisfy progression criteria, the mean value of the regression slopes for all test locations and the mean value of the regression slopes for progressing points only.
Progression indices dialog box.
The mean slope value has been used to investigate the effect of surgery on visual field progression in normal tension glaucoma.
Gaussian filtering
This technique improves the repeatability
and predictability of visual field tests (Crabb
DP, McNaught AI, Fitzke FW, Hitchings RA. Spatially
enhanced modelling of sensitivity decay in low-tension
glaucoma. In: Wall M, Heijl A, editors. Perimetry
Update. Amsterdam / New York: Kugler
Publications, 1994/1995:73-81.) Below is shown
the results of Gaussian filtering on an example cumulative
graphical display.
An example of Gaussian filtering. The left pane shows the unfiltered PROGRESSOR analysis. The right pane shows the same visual field series after the filter has been applied. The progressing locations in the superonasal area of the field appear to decay more regularly and to reach high statistical significance (as shown by white bars, p < 0.001) sooner after filtering has been performed.
Binocular simulation
The results of bilateral monocular visual field tests may be merged to give a representation of the central binocular visual field. In order to achieve this, the sensitivity value of any given test location in the left eye is compared with the sensitivity value of the corresponding test location in the right eye and the higher of the two sensitivity values is taken as the value to be displayed in the binocular simulation. The result is displayed in a gray scale format similar to the gray scale produced by the Humphrey Field Analyzer.
Binocular simulation display. The left
and middle panes show grayscales for
left and right eyes respectively. The right pane
shows the results of binocular simulation.
In addition, test locations in the binocular simulation with a sensitivity of less than 10 decibels may be highlighted, along with a ring which corresponds to the boundary of the central 20 degrees of the visual field. Locations which have a binocular sensitivity of less than 10 decibels and lie within the central 20 degrees of the visual field have an important bearing on the subject's legal fitness to drive in the United Kingdom.
Binocular simulation display identical
to that shown in Figure 3.6 except that
points in the binocular simulation with
a sensitivity of less than 10 dB and a blue ring
corresponding to the central 20 degrees of the visual
field are shown.
The binocular simulation analysis performed
by PROGRESSOR has been formally validated
and has been shown to be in good agreement
with the results of true binocular testing.(Crabb
DP, Viswanathan AC, McNaught AI, Poinoosawmy
D, Fitzke FW, Hitchings RA. Simulating binocular
field status in glaucoma. Br J Ophthalmol
1998;82(11):1236-1241.)
Help system
A comprehensive context-sensitive Help system has been built into the program. Users who are familiar with other Windows programs are able to use the software without a lengthy training period.
Download a demo and slide show presentation of PROGRESSOR
The PROGRESSOR demo and slide show presentation download contains a PowerPoint presentation which explains the theory and function of the PROGRESSOR software, and a demo version of the PROGRESSOR software itself.
Download progressor_demo.zip (9.92MB)
When prompted as below, click 'Save', and select a destination location on your computer:
To run the slide show and demo, extract this file to a destination on your hard drive, or other device such as a USB memory source. To extract the file using Windows XP, right-click on the file and select 'Extract All...'. You will be prompted to choose a destination location to extract the files to. If you do not have this option (e.g. Windows 2000) you will need to install WinZip or an equivalent unzipping program, in order to extract the files (www.winzip.com)
Once you have extracted the zip file to your destination location, browse to that location, for example, by double-clicking on your 'My Computer' icon and then navigating to your destination location. In the example below this is the D:\ drive. Double click on the file called 'Play' which you will subsequently see as highlighted in the following example:
'PowerPoint Viewer' will start. You may be asked to accept a licence agreement:
If so, simply click 'Accept' and the presentation will start. You do not need to have PowerPoint installed on your computer. The viewer, presentation and PROGRESSOR demo all run directly from disk, and no files are installed on your hard drive.
Once the presentation starts, you will have 4 options:
Demo - Click to run PROGRESSOR as a demo version.
Show - Click to view a presentation explaining PROGRESSOR (approx 10 mins).
NB: the presentation has a commentary throughout, so make sure your volume / speakers are switched on if you computer has speakers.
Buy - Click for an e-mail link to contact Medisoft about purchasing PROGRESSOR.
Quit - Exit the demo and presentation.
NB: When you click the 'Demo' button you may be asked the following question:
If so, click 'Yes' to run the demo. This may then be followed by another question:
If you see this message, click 'Run'.
For further information on running the slide show and demo download one of the following files:
progressor_demo_and_slide_show_set_up.pdf (pdf format) (147KB)
progressor_demo_and_slide_show_set_up.doc (Word format) (172KB)
For technical assistance contact support@medisoft.co.uk or call Medisoft on +44 113 384 6060.