oxymap analyzer instruction manual

Oxymap

Retinal Oximeter For use with Oxymap Analyzer version 2.2.1 revision 3844

Instruction manual

Oxymap ehf. Hamrahlid 17 105 Reykjavik Iceland

Tel: +354 552 6677 E-mail: [email protected] Website: www.oxymap.com

Date of issue: November 30, 2010

Copyright ©2010 Oxymap ehf. All rights reserved.

Instruction manual Oxymap Retinal Oximeter Oxymap Analyzer version 2.2.1 revision 3844

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Contents

Introduction ................................................................................................................................ 3

Intended use............................................................................................................................ 3

Clinical investigations......................................................................................................... 3

Cautions for use.......................................................................................................................... 4

Disposal .................................................................................................................................. 4

Environmental conditions for use .............................................................................................. 4

Storage........................................................................................................................................ 4

Environmental conditions for packaging in transportation ........................................................ 4

Checkpoints for maintenance ..................................................................................................... 5

User maintenance ................................................................................................................... 5

Replacing the fuse in the control box.................................................................................. 5

Validating the Oxymap Analyzer database......................................................................... 5

Backing-up the Oxymap Analyzer database....................................................................... 5

Escape clauses ............................................................................................................................ 5

Description ................................................................................................................................. 8

Main hardware components of the Oxymap Retinal Oximeter.............................................. 8

Oxymap Analyzer: Data manager – Patients view............................................................... 10

Oxymap Analyzer: Data manager – Analyses view............................................................. 11

Oxymap Analyzer: Main view ............................................................................................. 12

Basic operations ....................................................................................................................... 13

Starting up the oximeter ....................................................................................................... 13

Preparation for oximetry....................................................................................................... 13

Acquiring measurements with the Oxymap Analyzer software........................................... 13

Opening an image from the database ................................................................................... 17

Analysing oximetry image measurements............................................................................ 17

Data manager – Patients view .................................................................................................. 19

Window description.............................................................................................................. 19

Toolbar.................................................................................................................................. 20

Data manager – Analyses view ................................................................................................ 24



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Toolbar.................................................................................................................................. 25

Main view................................................................................................................................. 27


Toolbar.................................................................................................................................. 27

Additional tool...................................................................................................................... 29

Menus ....................................................................................................................................... 30

‘File’ menu ........................................................................................................................... 30

Commands ........................................................................................................................ 30

‘Tools’ menu......................................................................................................................... 33

Commands ........................................................................................................................ 33

‘Display’ menu ..................................................................................................................... 37

Commands ........................................................................................................................ 37

Appendix I – Oxygen saturation calculations .......................................................................... 41

Appendix II – Partial pressure of oxygen calculations ............................................................ 42

Appendix III - Fuse replacement.............................................................................................. 43

Appendix IV – Master switch .................................................................................................. 44


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Introduction

Intended use

The Oxymap Retinal Oximeter system is intended for non-invasive measurement of the retinal vessel oxygen saturation and the vessel width. The Oxymap Retinal Oximeter device captures images of the retina which are taken with a fundus camera. The Oxymap Retinal Oximeter software (Oxymap Analyzer) grabs, stores, displays and analyzes those images.

Clinical investigations

The Oxymap Retinal Oximeter is an investigational device intended for use in hospitals, eye clinics, research institutions or other research facilities for clinical investigations only. It is not intended to aid in diagnosing or monitoring diseases of the eye in individual patients.

The Oxymap Retinal Oximeter can be used by researchers to study retinal oxygenation in health and eye diseases. Such studies will add to earlier and more indirect evidence for the role of retinal oxygenation in eye diseases. The Oxymap Retinal Oximeter can also be used to compare oxygenation in groups of individuals or to compare oxygenation before and after treatment, such as medicinal or laser treatments. Retinal vessel width can be used in combination with oxygen saturation measurements in these studies.


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Cautions for use

Disposal

When disposing of Oxymap Retinal Oximeter parts, follow the local regulations for disposal and recycling.

Environmental conditions for use

Temperature: 10°C ~ 30°C Humidity: 30% ~ 75% (without dew condensation) Air pressure: 700hPa ~ 1060hPa

Storage

1. Environmental conditions (without package) Temperature: 10°C ~ 30°C Humidity: 30% ~ 75% (without dew condensation) Air pressure: 700hPa ~ 1060hPa

2. When storing the Oxymap Retinal Oximeter, ensure that the following conditions are met:

- The Oxymap Retinal Oximeter must not come in contact with water. - Store the Oxymap Retinal Oximeter away from environments where air

pressure, temperature, humidity, ventilation, sunlight, dust, salty/sulphurous air, etc. could cause damage.

- Do not store or transport the Oxymap Retinal Oximeter on a slanted or uneven surface or in an area where it is subject to vibrations or instability.

- Do not store the Oxymap Retinal Oximeter where chemicals are stored or gas is generated.

Environmental conditions for packaging in transportation

Temperature: -20°C ~ 50°C Humidity: 10% ~ 95%


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Checkpoints for maintenance

1. Periodically inspect the Oxymap Retinal Oximeter and its parts. 2. Before using the Oxymap Retinal Oximeter again after a long period of inactivity

make sure that it operates safely and normally. 3. Read the chapters concerning maintenance in the fundus camera instruction manual.

User maintenance

To ensure the safety and performance of the Oxymap Retinal Oximeter all maintenance work, unless specified in this manual, shall be conducted by trained service engineers.

Replacing the fuse in the control box

The fuse which is in the control box may be replaced by users. Information on the master switch may be found in Appendix III, page 43.

Validating the Oxymap Analyzer database

Users may test the integrity of the Oxymap Analyzer database before exiting the software. Further information may be found in this manual, page 32.

Backing-up the Oxymap Analyzer database

It is recommended to back-up the Oxymap Analyzer database regularly (cf. pages 32 and 35).

Escape clauses

• Oxymap shall not take any responsibility for damage due to fire, natural disasters, actions by third persons or other accidents, or damage due to negligence or misuse by the user or any use under unusual conditions.

• Oxymap shall not take any responsibility for damage resulting from inability to properly use this instrument, such as loss of business profit or suspension of business.

• Oxymap shall not take any responsibility for damage caused by using this instrument in a manner other than that described in this instruction manual.


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Warnings and Cautions

Before using the system, users must be trained by Oxymap or an authorized agent and read all safety information.

CAUTION--Investigational device. Exclusively limited by American and European laws to investigational use.

CAUTION : To avoid injury while installing or removing the Oxymap Retinal Oximeter, tighten the inclination mechanism of the fundus camera.

CAUTION : When installing the Oxymap Retinal Oximeter on top of the fundus camera, secure it firmly by fastening the upper mount locking lever. If installed loosely, the oximeter may fall off, leading to severe damage and bodily injury.

WARNING : To avoid discomfort or damage to the patient's eye, do not brighten the illumination lamp more than necessary.

WARNING : To avoid discomfort or damage to the patient's eye, do not illuminate the eye longer than necessary.

WARNING : To avoid discomfort or damage to the patient's eye, do not make a flash intensity level higher than necessary.

CAUTION : Set the filter switching knob of the fundus camera to F2 for retinal oximetry. The filter located in the F2 slot of the filter frame of the fundus camera passes wavelengths from 545 nm to 615 nm and thus filters ultraviolet and infrared wavelengths.

CAUTION : Select the 50° field of view on the fundus camera for retinal oximetry. If 20° or 35° fields of view are selected, the vessel detection algorithm of Oxymap Analyzer may not function correctly and make wrong retinal vessel oxygen saturation and vessel width measurements.

WARNING : To prevent damage and injuries, use the power supply provided with the Oxymap Retinal Oximeter.

WARNING : To avoid electric shock, do not splash any liquids or insert any objects into any vents or slots of the Oxymap Retinal Oximeter.

WARNING : To avoid fire and electric shock in case of leakage, be sure to use a grounded receptacle. Do not connect to receptacles that are not grounded.


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WARNING : To avoid electric shock do not handle the plugs with wet fingers.

CAUTION : The Oxymap Retinal Oximeter is built on Topcon TRC-50DX, TRC-50IX and TRC-50EX fundus cameras. Trying to use another model of fundus camera may adversely affect the system.

CAUTION : Unauthorized modifications or additions to the Oxymap Retinal Oximeter and accessories may adversely affect the system.


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Description

Main hardware components of the Oxymap Retinal Oximeter

Figure 1. The Oxymap Retinal Oximeter mounted on the Topcon TRC-50DX fundus camera

Control box

(Electronic circuit)

Digital cameras

Optical adapter

Angle changing

lever

Oxymap

Retinal Oximeter

Topcon

TRC-50DX

Fundus camera

Filter switching

knob


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The following hardware components are used to:

Topcon TRC-50DX/IX/EX fundus cameras: Observe and photograph the fundus of the eye.

Filter switching knob Select different kinds of photography.

Angle changing lever Select the angle of coverage.

Other components Further instructions may be found in the fundus camera user manual.

Optical adapter: Mount the digital cameras on the fundus camera.

Lenses and filter set Select the wavelengths used for oximetry and direct the light in the digital cameras.

Diagnostic Instruments SPOT Insight IN1800 digital cameras: Capture the images taken with the fundus camera and produce spectral images.

Communication cable (IEEE 1394) Transfer the spectral images from the digital cameras to the computer.

Control box (electronic circuit): Turn on the Oxymap Retinal Oximeter and initiate the photography.

Power supply Power the Oxymap Retinal Oximeter.

Control cable (serial DB-9) Connect the electronic circuit to the fundus camera’s CONTROL terminal.

Power cables (2.5 mm Barrel Plug) Power the digital cameras.

Signal cables (TS connectors) Synchronize the digital cameras with the fundus camera flash.


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Oxymap Analyzer: Data manager – Patients view

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Oxymap Analyzer: Data manager – Analyses view

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view


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Oxymap Analyzer: Main view

Fig

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4. M

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Basic operations

Starting up the oximeter

1. Check the cable connections. 2. Power up the fundus camera.

Note: An alarm will sound and “Err8” will be displa yed on the control panel screen. To dismiss the error notification, press the photography switch on top of the joystick of the fundus camera for a few seconds. The error notification will disappear and the beep will stop.

3. Power up the Oxymap Retinal Oximeter: a. Make sure that both digital cameras are turned on (|). b. Then turn the control box master switch on (|).

The power switch on the control box is the master switch for both digital cameras (cf. Appendix IV, page 44).

Preparation for oximetry

1. Read the chapters about preparation for photography and preparation of the patient in the fundus camera instruction manual.

2. Select the UPPER port of the fundus camera to enable photography using the Oxymap Retinal Oximeter.

3. Select the 50° field of view on the fundus camera. 4. Set the filter switching knob to F2 on the fundus camera.

Acquiring measurements with the Oxymap Analyzer software

1. Start up Oxymap Analyzer. 2. In the Data manager:

- Select an existing patient. - Or click the ‘New patient’ button in the Patients view toolbar to create a new

patient. The ‘Patient editor’ dialog box opens.


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Figure 5. ‘Patient editor’ dialog box

Fill in patient information and click the ‘Save’ button. The created patient should be selected in the patients list. Please be aware that there are some restrictions on patient information:

o Every patient must have a first and last name. o The personal number, if entered, must be unique. o No two patients may be exactly identical. In the case where the

names are identical and no personal number has been entered a different date of birth or a comment may be used to distinguish between the patients.

3. Click on ‘New session’ in the Patients view toolbar to create a new session. The ‘Session editor’ dialog box opens:

Figure 6. ‘Session editor’ dialog box


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Fill in the session information, if desired, and click on ‘Save’. The new active session is added to the ‘Session’ list.

4. Begin the image acquisition by pressing the photography switch on the fundus camera joystick. The images will be automatically processed by Oxymap Analyzer.

5. Large views of the images being acquired can be opened by double-clicking on a particular image in the ‘Processing queue’ dialog box:

Figure 7. ‘Processing queue’ dialog box

6. Once the images have been processed, they appear as thumbnails in the rightmost panel. Image can be closed or deleted by right-clicking on their thumbnail. It is also possible to close all the images.


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Figure 8. Thumbnails options

The ‘Delete image’ option is only active when a session is in progress.

Patient and session information can be edited or a session ended at any time using the dedicated buttons in the ‘Session in progress’ toolbar:

Figure 9. ‘Session in progress’ toolbar


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Opening an image from the database

1. Click the ‘Data manager’ button in the Oxymap Analyzer toolbar to open the Data manager (cf. Figures 2 and 13, pages 10 and 19).

2. Select a patient and a session: - Select one image in the ‘Images’ lists. - Or hold Shift to select several images of interest.

3. Click on ‘Open’ in the ‘Information’ panel. Open images appear as thumbnails on the right panel of the screen.

Analysing oximetry image measurements

1. Scroll down to the bottom of the thumbnail panel if many images are open to find the image of interest.

2. Double-click on the image of interest in the thumbnail panel to open a large view of it with a colour-coded saturation map (cf. Figures 4 and 20, pages 12 and 27).

3. Should the parameters used to calculate the retinal oxygen saturation values for that image be different from the parameters set in the Oxymap Analyzer software, a dialog box pops up to recalculate the oxygen saturation:

Figure 10. ‘Recalculate saturation values?’ dialog box

4. Press in the Oxymap Analyzer toolbar to select the vessel selection tool. 5. Select a vessel segment:

- Click once on the vessel in question on the large view of the image to select a whole vessel segment.

- Hold the left mouse button down and drag it along the vessel in question to select only parts of it.

Selected vessel segments appear white on the saturation map. 6. To deselect a vessel segment click on the background of the large view of the image,

i.e. an area of the retina without vessels. 7. To view measurement details for a selected vessel, open an analysis table by selecting

‘New analysis table’ in the ‘File’ menu or pressing Ctrl+N. Select ‘Add selected vessel segment to analysis’ in the ‘Tools’ menu, or press Ctrl+D, to add the vessel in question to the analysis table.


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Figure 11. Analysis table with measurements

8. Right-click on the analysis table to open additional analysis tools and copy measurements to the clipboard:

Figure 12. Analysis table, additional options

Paste the copied measurements in a spreadsheet. More details on the copied data may be found pages 31, and 33-34.


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Data manager – Patients view

Figure 13. Data manager – Patients view

Window description

The Patients view contains all the data about existing patients, i.e. patient information, photography sessions, and images.

The ‘Patients’ list contains all the existing patients, listed by family name, first name and personal number. By default, the columns order is ‘Family name’, ‘First name’ and ‘Personal number’. It can be changed by dragging and dropping the column headers but will not be saved after the software has been closed. By default, patients are sorted by family name in alphabetical order. Clicking on the column headers reverses the alphabetical order in the columns ‘Family name’ and ‘First name’ and the numerical order in the column ‘Personal number’. Those changes are not saved when the Oxymap Analyzer is closed.


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The ‘Quick search’ field enables to look for a patient in the Oxymap Analyzer database. First, middle or family names, personal numbers, and comments on patients can be used to search for a patient in the patient list. The ‘Reset’ button clears the search results.

The ‘Sessions’ list contains all the photography sessions carried out for a particular patient. Photography sessions are ordered chronologically.

The ‘Images’ list contains all the images taken during a particular photography session. Images are ordered by their creation date in descending order.

It is possible to navigate between the ‘Patients’, ‘Sessions’ and ‘Images’ lists using the keyboard arrow keys.

The ‘Information’ panel displays information about a patient, a session or an image depending on whether a patient, a session or an image is selected in the respective lists. Click ‘Edit’ to edit patient, session or image information. Click ‘Cancel’ to cancel the changes made or ‘Save’ to save them.

To open an image, select a patient, a particular session and the image in question. Double-click on the image name or click on the ‘Open’ button in the ‘Information’ panel. To open multiple images, press Shift and select the images of interest. Click on the ‘Open’ button in the ‘Information’ panel. Thumbnails of open images appear in the rightmost panel. Right-click on the thumbnail of an image to close the image or close all images. The “Delete image” option is only active when a session is in progress.

Toolbar

Figure 14. Patients view toolbar

New Patient Creates a new patient


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1. Click on the ‘New patient’ button to open the ‘Patient editor’ dialog box:

Figure 15. ‘Patient editor’ dialog box

2. Fill in patient information. Please be aware that there are some restrictions on patient information: - Every patient must have a first and last name. - The personal number, if entered, must be unique.

- No two patients may be exactly identical. In the case where the names are identical and no personal number has been entered a different date of birth or a comment may be used to distinguish between the patients.

3. Confirm in order to add new patients to the Oxymap Analyzer database.

New Session Creates a new session for a selected patient

1. Select a patient in the ‘Patients’ list. 2. Click the ‘New session’ button to open the ‘Session editor’ dialog box.


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Figure 16. ‘Session editor’ dialog box

3. Fill in the session information, if desired, and click on ‘Save’ to start a new session for the selected patient.

Import Imports data into the Oxymap Analyzer database

1. First: - To import an image select a patient and a session. - Or to import a session select a patient. - Or to import a patient unselect any patient selected in the ‘Patients’ list by

pressing Ctrl and clicking on the particular selected patient. 2. Click on the ‘Import’ button. 3. Find the directory where the data to import is. 4. Select the data to import. 5. Start importing.

Export Exports patients, sessions or images from the Oxymap Analyzer database

1. Select a patient, a session or an image in the respective columns. 2. Click the ‘Export’ button. 3. Choose a directory where to export the data. 4. Start exporting.

Patients are exported in the .pat format, sessions in the .ses format and images in the .ret format.


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Delete Deletes patients, sessions or images from the Oxymap Analyzer database.

1. Select a patient, a session or an image in the respective columns. 2. Click on the ‘Delete’ button. 3. Confirm.


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Data manager – Analyses view

Figure 17. Data manager – Analyses view

Window description

The Analyses view contains the analyses which have been previously carried out and saved.

Analyses are listed in the central column called ‘Analyses’. It is possible to navigate in the ‘Analyses’ column using the keyboard arrow keys.

The ‘Quick search’ field enables to look for an analysis in the Oxymap Analyzer database. Patient or image names, and comments made within an analysis can be used to search for an analysis in the database. The ‘Reset’ button clears the search results.

The ‘Information’ panel displays information about a selected analysis. Click ‘Edit’ to edit the analysis information. Click ‘Cancel’ to cancel the changes made or ‘Save’ to save them.


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Click ‘Open’ to open an analysis or double-click on the analysis name. The analysis table and associated retinal images open.

Toolbar

Figure 18. Analyses view toolbar

New analysis Opens a new analysis table

Figure 19. Analysis table

Measurements from different vessel segments can be collected in the table and saved in the database.

Save search Saves the search words used in the ‘Quick search’ field

Saved searches are listed in the leftmost column called ‘Saved searches’.

Copy analysis Creates an exact copy of a selected analysis

1. Select an analysis in the ‘Analyses’ list. 2. Click the ‘Copy analysis’ button. 3. A copy of the selected analysis is automatically created and added to the ‘Analyses’

list.

‘Copy analysis’ is only active when an analysis has been selected in the central ‘Analyses’ column.


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Delete Deletes selected saved searches or analyses

1. Select an analysis in the ‘Analyses’ list. 2. Click on ‘Delete’. 3. Confirm.

‘Delete’ is only active when a saved search or an analysis have been selected.


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Main view

Figure 20. Main view

Window description

The Main view contains a large view of an image that has been opened from the data manager and then selected in the thumbnail panel. The thumbnail of the image selected appears in a yellow frame.

Toolbar

Figure 21. Main view toolbar

Data manager Opens the Oxymap Analyzer database


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Vessel selection tool Selects vessels on the large view of an image

A vessel segment on the large view of an image can be selected for detailed analysis:

1. Choose the vessel selection tool. 2. Select a vessel.

- Select a whole vessel segment by clicking once on the vessel in question on the large view of the image.

- Select a vessel segment part by holding the left mouse button down and dragging it along the vessel in question.

A selected vessel appears white on the saturation map.

Zoom tool Zooms in or out on the large view of an image

- To zoom in, select the zoom tool and left-click on the image. - To zoom out, click the image while holding the Ctrl key down.

It is also possible to zoom in and out with the scroll wheel of the mouse.

/

Exclusion tool / Un-exclusion tool Excludes or un-excludes vessel segments areas

Areas of the retina can be excluded and un-excluded from the calculation of oxygen saturation. By selecting the exclusion tool, it is possible to mark the area that is to be excluded with a brush tool (cf. Figure 40, page 39).

Excluded areas can be un-marked by using the un-exclusion tool.

It is possible to adjust the size of the exclude and un-exclude brushes. The option is available after the exclusion or un-exclusion button has been pressed:

Figure 22. Brush size tool

Those tools are only active when an analysis table has been opened.


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The toolbar changes when a session or an analysis is in progress:

Figure 23. Session in progress toolbar

Figure 24. Analysis in progress toolbar

Additional tool

Brightness and contrast tool Adjusts the brightness and contrast of the large view of an image

Figure 25. Brightness and contrast tool

1. Click on on the bottom left corner to open the brightness and contrast tool. 2. Adjust the brightness and/or the contrast as desired.

Changes to image brightness and contrast values are saved.


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Menus

All the commands are accessible with a shortcut.

‘File’ menu

Figure 26. ‘File’ menu

The ‘File’ menu has the following commands: - ‘Data manager’, Ctrl+B - ‘New analysis table’, Ctrl+N - ‘Back up database’, Alt+K - ‘Quit’, Alt+Q

Commands

Data manager (Ctrl+B) Opens the Oxymap Analyzer database

The window has two views selected by clicking the following icons on the left of the screen.

In the Patients view it is possible to view and open previously acquired images which are stored with patient information and session date (cf. page 24).

In the Analyses view data related to the analysis of vessel segments can be managed (cf. page 19).

New analysis table (Ctrl+N) Opens a new analysis table


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Figure 27. Analysis table

Measurements from different vessel segments can be collected in the table and saved in the database.

Analysis tables have eight columns: - ‘Image name’: name of the image in which the selected vessel segment is. - ‘ODR (mean)’: mean ODR of the selected vessel segments (cf. Appendix I,

page 41). - ‘ODR (SD)’: standard deviation of the ODR of the selected vessel segments. - ‘SatO2 %’: calculated oxygen saturation of the selected vessel segments, in

percentage. - ‘PO2 [mmHg] (derived)’: calculated partial pressure of oxygen of the selected

segments, in mmHg (cf. Appendix II, page 42) - ‘Width (pixels)’: mean width of the selected vessel segments, in pixels. - ‘# points’: number of points along the selected vessel segments used for

calculations. - ‘Notes’: notes for each selected vessel segment can be written after a double

click, for example to label the segment for later analysis in a spreadsheet program.

Rows of the following table contain measurements of selected vessel segments:

Figure 28. Analysis table with measurements

The first row is highlighted in blue, which means that this vessel segment has been selected in the table. This particular vessel appears white on the large view of the image it belongs to. The second row is yellow, i.e. the corresponding vessel segment belongs to the image whose large view is currently opened. The last rows appear white: the vessels which are measured are from open images accessible in the thumbnail panel.

Save To save the current analysis table to the Oxymap Analyzer database click on the ‘Save’ button on the lower right corner of the table. Name the analysis and confirm.


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Closing an analysis closes the analysis table and all the pictures that belong to the analysis.

Additional analysis tools

Figure 29. Analysis table, additional options

Right-click on the analysis table to open additional analysis tools: - ‘Copy row values’: copies one selected row to the clipboard. - ‘Copy selected row values’: copies several selected rows to the clipboard. Hold

Ctrl and click to select multiple rows. - ‘Copy all rows’ (Ctrl+A): copies all the rows to the clipboard. - ‘Copy vessel point data’: copies the point data of a selected vessel segment to

the clipboard. - ‘Delete analysis item’ (Del): deletes a selected vessel segment from the

analysis table. Go to a spreadsheet program to paste (Ctrl+C) the selected data.

Back up database (Alt+K) Opens the ‘Backup manager’ dialog box in order to back up the Oxymap Analyzer database

Figure 30. ‘Backup manager’ dialog box

Quit (Alt+Q) Closes the program.

It is also possible to check the database integrity here. In that case the program will be closed automatically after the test has been performed.


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Figure 31. ‘Confirm exit’ dialog box

All unsaved data is lost when the Oxymap Analyzer is closed.

‘Tools’ menu

Figure 32. ‘Tools’ menu

The ‘Tools’ menu has the following commands: - ‘Add selected vessel segment to analysis’, Ctrl+D - ‘Copy selected vessel segment point info to clipboard’, Ctrl+C - ‘Preferences’, Alt+P - ‘About’, Alt+A

Commands

Add selected vessel segment to analysis (Ctrl+D) Adds a selected vessel segment to an analysis table

Vessel segments can be selected from the large image by a simple mouse click. The selected vessel segment becomes white. A part of a vessel segment can also be selected by holding down the left mouse button while dragging the mouse pointer along the vessel.

Copy selected vessel segment point info to clipboard (Ctrl+C) Copies the point data of a selected vessel segment to the clipboard

Pasting into a spreadsheet reveals details on each measurement point along the selected vessel. Each row contains information on one measurement point (cf. Appendix I, page 41).


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Column details are: - Outside intensity for isobestic wavelength (570 nm), I_0_570nm. - Vessel intensity for isobestic wavelength (570 nm), I_570nm. - Outside intensity for non-isobestic wavelength (600 nm), I_0_600nm. - Vessel intensity for non-isobestic wavelength (600 nm), I_600nm. - Optical density for isobestic wavelength (570 nm), OD_570nm. - Optical density for non-isobestic wavelength (600 nm), OD_600nm. - Optical density ratio calculated with OD _600nm/OD_570nm. - Optical density ratio calculated from vessel values. - Oxygen saturation. - Vessel width in pixels. - X: pixel position on the horizontal axis. - Y: pixel position on the vertical axis.

Note: The optical density ratio calculated with OD_600nm / OD_570nm is calculated with the values of OD_570nm and OD_600nm, themselves calculated with the intensity values I_0_570nm and I_570 nm, and I_0_600nm and I_600nm. The optical density ratio calculated from vessel values is calculated after filtering the intensity of light inside and outside the vessels (noise reduction). Those intensity values are not given in the table. This option is currently not in use.

Preferences (Alt+P) Opens a dialog box which allows to set preferences

Saturation calculation view Parameters for saturation calculations can be changed here. For a brief overview of how the oxygen saturation values are derived, cf. Appendix I, page 41.

Note: Care should be taken while modifying any of the parameters set in the Oxymap Analyzer software since any modification will have an outcome on measurements and thus on research results.


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Figure 33. ‘Preferences’ dialog box – Saturation calculation view

The saturation calculations preference dialog box has the following options: - ‘a’ and ‘b’ parameters: The linear equation that converts from ODR values to

oxygen saturation can be changed by editing the parameters a and b (slope and intercept).

- ‘Outside vessel averaging area’: controls the length of the edge of the square used to sample the background area outside the vessel.

- ‘Inside vessel averaging area’: controls the length of the edge of the square used to average the vessel segments intensity values.

- ‘Display O2 saturation calculation parameters on images’: The values of the parameters a and b used for calculation appear in the lower right corner of the images, below the oxygen saturation scale.

- ‘Minimum valid vessel width’: The vessels whose width is below the set value are excluded from calculations and appear grey on the large view of images.

Misc options

Select or unselect “Quit without asking”.

Enable or disable daily backups. Choose the daily backup time and the backup location. Oxymap Analyzer must be open so that automatic backups are carried out.

Note: It is recommended to back-up the Oxymap Analyzer database regularly.


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Figure 34. ‘Preferences’ dialog box – Misc options view

About (Alt+A) Gives information about the Oxymap Analyzer revision, the camera driver and the digital cameras configuration:

Figure 35. ‘About’ dialog box


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‘Display’ menu

Figure 36. ‘Display’ menu

The ‘Display’ menu has the following commands. - ‘Hide/Show vessel map’, F1. - ‘Display isosbestic band’, F2. - ‘Display measurement band’, F3. - ‘Hide/Show exclusion map’, F4. - ‘Hide/Show selected vessel measurements points’, F7. - ‘Hide/Show color map’, F9.

The ‘Display’ menu is only active when an image has been opened.

Commands

‘Hide/Show vessel map’ (F1) Toggles the vessel map overlay:

Figure 37 Vessel map overlay


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Blue pixels are defined as belonging to a vessel. The vessel map is the output from the vessel detection algorithm and is used for the vessel width calculations.

Display isobestic band (F2) Displays the isobestic spectral band (570nm), which is almost insensitive to oxygen saturation:

Figure 38. Isobestic spectral band (570nm)

Display measurement band (F3) Displays the 600nm spectral band which is sensitive to changes in oxygen saturation:

Figure 39. Measurement spectral band (600nm)


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600nm is the oxygen sensitive wavelength; the arteries become almost transparent on the image.

Press alternatively F2 and F3 to switch between the two spectral band images.

Hide/Show exclusion map (F4) Toggles the exclusion map (map visibility does not affect the calculations):

Figure 40. Exclusion map

The exclusion map is displayed in white on the image on the top. It is hidden on the image on the bottom after having pressed F4. The selected segment is highlighted in white, while the excluded areas are grey.

Hide/Show selected vessel measurement points (F7) Displays measurement points positions after a vessel segment has been selected


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Figure 41. Position of measurement points

Small red points show the position of measurement points outside the selected vessel segment. Green points show measurement points on vessels for the oxygen insensitive wavelength. Yellow points show the position of the vessel measurement points for the oxygen sensitive wavelength.

Hide/Show saturation colour map (F9) Toggles the oxygen saturation colour map overlay:

Figure 42. Oxygen saturation colour map overlay


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Appendix I – Oxygen saturation calculations

According to Beer-Lambert law, light transmission through a solution diminishes logarithmically as the concentration of the solution and the distance through it increase. This is expressed as

where I is the intensity of light transmitted through the solution, I0 is the original intensity, d is the thickness of the solution, C is the concentration and ε is the extinction coefficient, which specifies the fraction of light lost to absorption per unit distance and unit concentration in a particular medium at a specific wavelength of light. We define optical density as

In retinal oximetry I and I0 are estimated based on the amount of light reflected from the retina. Retinal oximetry assumes that a large fraction of the incident light is reflected back by the tissues surrounding the vessels. The optical density is then defined as

The optical density ratio (ODR) is defined as

where OD600 is the optical density calculated using light at 600 nm, a wavelength of light sensitive to the saturation of oxygen in blood and used in our system. OD570 is the optical density calculated using light at 570 nm, which is insensitive to oxygen saturation. It can be shown that it exists a linear relationship

where SatO2 is the oxygen saturation of haemoglobin in the blood.


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Appendix II – Partial pressure of oxygen calculations

The PO2 calculations are based on the following publications: - Severinghaus, JW. Simple, accurate equations for human blood O2 dissociation

computations. J Appl Physiol 1979; 46 (3):599-602. - Severinghaus, JW. Determination of PO2 from saturation [reply]. J Appl

Physiol 1989;67:902. Note: The calculations assume pH = 7.4 and T = 37.0°C.


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Appendix III - Fuse replacement

The fuse which is in the trigger box can be replaced by opening the box.

1. Turn the power switch off and unplug the power cord. 2. Loosen the four screws holding the cover of the box. 3. Carefully take the cover off with the circuit inside and lay them on a table. 4. If the fuse has blown out, the whole instrument will not operate. Replace the fuse with

a new one.

Fuse specifications:

Termination Style: Cartridge

Fuse Type: Fast Acting

Body Material: Glass

Fuse Size / Group: 3AG

Current Rating: 4 Amps

Voltage Rating: 250 Volts

Interrupt Rating: 10 KAmps at 125 VoltsAC / 35 Amps at 250 VoltsAC

Packaging: Bulk


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Appendix IV – Master switch

The power switch on the control box should be used as the Oxymap Retinal Oximeter master switch.

Turn the master switch OFF (O) to turn the device OFF. This means that both the cameras can be switched ON (|) all the time since no power is supplied to them if the master switch is turned OFF.

Trigger box

Camera 2

Camera 1

ON

ON

Master switch

ON

Figure 43. Master switch is turned ON (|) and both digital cameras are turned ON (|).

Camera 2

Camera 1

Trigger box

Off

Master switchOff

Off

Figure 44. The whole device is turned OFF since the master switch is turned OFF (O). No power is supplied to the

cameras in this stage although the power switch on each camera is switched ON (|).

Oxymap ehf. Hamrahlid 17 105 Reykjavik Iceland

Tel: +354 552 6677 E-mail: [email protected] Website: www.oxymap.com

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