Frequently Asked Questions About HRT II Glaucoma

1. How does corneal curvature (c-curve, average K-value) affect the data?
2. Do I have to enter in the corneal curvature (c-curve, average K-values)?
3. Why do I need to correct for astigmatism?
4. When do I need to correct for astigmatism?
5. How do I correct for astigmatism?
6. Do I always need to use the same method to correct for astigmatism?
7. What is the proper patient position?
8. What is important when acquiring images?
9. How do I get the reflection off of the screen when the patient is wearing glasses?
10. How do I make sure the laser is centered on the pupil?
11. How do I focus an image correctly?
12. How do I adjust or bracket the focus?
13. How important is it to have the optic nerve head centered?
14. What does the sensitivity number indicate?
15. What if the sensitivity is above 94%?
16. What can I do if the images are really dark?
17. What does the error message “Uncorrected astigmatism or too high too deep” mean?
18. Why has the green button at the bottom of the acquisition window turned to red?
19. The images I just acquired do not appear on the screen, where are they?
20. What does the box symbol above an image mean?
21. Why would I get a failed topography?
22. How do I review the movie of an acquired image?
23. Why are there black borders around the image
24. Why has the follow-up image shifted from the center of the screen?
25. Can I change the date of an examination?
26. Can I place contour line points on blood vessels?
27. Does adjusting the pivot point when drawing a contour line affect the measurements?
28. How do I know if a contour line is placed properly?
29. How many points should I use to draw the contour line?
30. Can I modify or change a contour line?
31. When should I use the manual alignment feature?
32. Why does the Moorfields classification change if I modify the contour line?
33. Why isn’t the contour line importing properly?
34. Why is there an x or an ! in the center of the image?
35. What are follow-up images compared to?
36. How do I get a progression analysis?
37. What does each graph measure on the Progression Trend Report?
38. What is the Moorfields Regression Analysis classification based on?
39. What does “Cup Shape Measure” mean?
40. What is the Linear Cup/Disc area ratio?
41. Why does the cup/disc ratio not match my clinical assessment of cup/disc ratio?
42. On a follow-up printout, how do I determine how much change has occurred?
43. Why do I have a black and white topography image on the follow-up printout?
44. Is there a printout for the Topographic Change Analysis (Progression)?
45. How can I print the 3-D image?
46. What is the memory size of an image?
47. How often should I archive?
48. Do I have to manually select which patients to archive?
49. Do I need to format my new magneto optical (MO) disk?
50. How do I format a new Magneto Optical (MO) disk?
51. How many exams does a Magneto Optical (MO) disk hold?
52. If the “Shortcut to Removable Disk” is broken or missing, how can I fix it?

1. How does corneal curvature (c-curve, average K-value) affect the data?

   Corneal curvature information is used in combination with focus information to correct for magnification. The focal length of the eye and, therefore, the absolute scaling of the acquired image is dependent on the radius of curvature of the anterior corneal surface. If no other value is entered, the HRT software uses a default value of 7.7 mm. However, if the correct radius of corneal curvature is different from that of the default value and is not entered properly, the measurement results will not be correct. The amount of error in the HRT results increases with increasing deviation of the actual radius of corneal curvature from the assumed default of 7.7 mm.

2. Do I have to enter in the corneal curvature (c-curve, average K-values)?

   Yes, the corneal curvature (average K-reading) must be entered at all baseline examinations. C-Curve information is used in combination with focus information to correct for magnification. The C-Curve does not need to be updated at follow-up examinations unless it changes by more than 0.50 diopters. Changes of more than 0.50 diopters can occur due to cataract surgery, refractive surgery, corneal pathology, etc.

3. Why do I need to correct for astigmatism?

   Astigmatism introduces an optical rotation into the image. This rotation must be corrected for using astigmatic corrective lenses. Astigmatism greater than 1.0 diopters leads to changes of the focal plane of the eye which are greater than the HRT's depth resolution, affecting image quality.

4. When do I need to correct for astigmatism?

   Astigmatism greater than 1.0 diopters must be corrected for by using Heidelberg Engineering’s astigmatic magnetic lenses, the patient’s glasses, or the patient’s contact lenses. Heidelberg Engineering's astigmatic magnetic lenses are the recommended correction method. You do not need to correct for astigmatism less than or equal to 1.0 diopters.

5. How do I correct for astigmatism?

   Astigmatism may be corrected for by using Heidelberg Engineering’s astigmatic magnetic lenses, with the patient’s glasses or with the patient’s contact lenses. Heidelberg Engineering’s astigmatic magnetic lenses are the recommended method.

   If the patient’s cylinder is less than or equal to 1.0 diopter, do NOT use any corrective lens.

   If the patient’s cylinder is greater than 1.0 diopter, the select the type of corrective lenses being used for imaging in the Eye Data box before continuing on with image acquisition.

6. Do I always need to use the same method to correct for astigmatism?

   Yes. The method you choose to correct for astigmatism should be consistent throughout a patient’s exams so that images may be compared over time.

   If the patient’s first examination is conducted with glasses, contact lenses, or astigmatic lenses, then all subsequent examinations for this patient should be conducted in the same manner. If the patient does not have an astigmatism greater than 1.0 diopter, then the patient does not need to wear corrective lenses.

7. What is the proper patient position?

   The patient should have their head fully against the headrest and chinrest. The patient chair, table and the chinrest should be adjusted so that the patient's eye is level with the canthus mark (red hatch mark) on the side of the headrest.

   --------------------------------------------------------------------------------
   Ask the patient to position their head firmly against the headrest and chinrest. The height of the chinrest should be adjusted so that the eye being examined is located at the height of the canthus mark on the headrest. Adjustment of the table and/or chair height may be necessary to ensure patient comfort. Ensure that the patient's head is not tilted.

8. What is important when acquiring images?

   [Insert Image]

   The patient position, correct focus settings, and laser alignment are all important when acquiring images.

   --------------------------------------------------------------------------------
   - Patient comfortable and in proper position (fully in head and chin rest, and not tilted)
   - Patient properly fixated on internal (glaucoma module) or external (retina module) target
   - Camera distance just outside the eyelashes
   - Laser centered directly into the pupil without any halos of light falling onto the iris
   - Optic nerve head or fovea centered
   - Focus on brightest point of retinal surface (clear orangish-yellow color)
   - Light evenly distributed across image
   - Review movie for eye movement

9. How do I get the reflection off of the screen when the patient is wearing glasses?

   Tilt the earpieces down with a pantoscopic tilt, still keeping the lenses close to the patient’s head in order to move the reflective artifact off-screen.

10. How do I make sure the laser is centered on the pupil?

    Carry out a visual check to be sure the laser is centered in pupil and that no light is falling onto the iris. In the case of a small pupil, dilation is recommended.

    --------------------------------------------------------------------------------
    For fine adjustment of the image, move the camera slightly up and down, and then sideways until the image appears brightest. This is the point at which the laser beam falls directly into the center of the pupil of the eye being examined.

    PLEASE NOTE: if you dilate the patient for one exam, all subsequent exams should be performed with dilation as well.

11. How do I focus an image correctly?

    HRT II - Glaucoma & Retina Modules

    If the patient is not wearing glasses or contact lenses, start with the focus dia at the spherical equivalent (1/2 cylinder + sphere)
    If the patient is wearing glasses or contact lenes, start with the focus set to 0 diopters
    Adjust or "bracket" the focus
    Focus on the highest part of retinal surface
    Evenly distribute light across the image
    Maximize the number of blue quality bars
    Minimize sensitivity to be as low as possible by re-checking laser alignment to center of the patient's pupil

    HRT3 Glaucoma & Retina Modules and v3.0 Glaucoma software for HRTII

    If the patient is not wearing glasses or contact lenses, start with the focus dial set at the spherical equivalent (1/2 cylinder + sphere)
    If the patient is wearing glasses or contact lenses, start with the focus dial set to 0 diopters
    Adjust or "bracket" the focus
    Focus on the highest part of retinal surface
    Evenly distribute light across the image
    Maximize length of the image quality control bar to be as far to the right as possible
    Adjust focus to try to obtain a "green" image quality control bar
    Maximize image quality score (100% being the maximum)

12. How do I adjust or bracket the focus?

    Begin by setting the focus at the patient's spherical equivalent, and then adjust the focus dial in each direction until the light is distributed evenly (no shadowing)on the retina and there is even illumination.

    If the patient is not wearing corrective lenses (glasses or contacts), start by setting the focus dial - on the end of the camera - to the patient's spherical equivalent (1/2 cylinder + sphere)
    If the patient is wearing corrective lenses (glasses or contacts), start with the focus setting at 0 diopters. Adjust or "bracket" the focus until the overall image appears brightest. Turn the focus one click to the left, does the image brighten? If not, turn the focus to the right. If the image darkens, you have gone too far

13. How important is it to have the optic nerve head centered?

    It is very important to try to center the optic nerve head at each exam so that the exams may be easily compared over time. The effect of having the optic nerve head off-center in images compounds over time, reducing the data available to perform progression analysis.

    --------------------------------------------------------------------------------
    An optic nerve head not centered properly may affect proper import of the contour-line on subsequent images.

    Manual alignment of HRT II and HRT3 images is available when an image is acquired that is off-center.

14. What does the sensitivity number indicate?

    Sensitivity is an indicator of how much light the laser has to output to get the best image as well an indicator of quality.

    --------------------------------------------------------------------------------
    - Aim for a sensitivity between 60 – 80%
    - Try to keep the sensitivity as low as possible by centering the laser in the pupil, hydrating the cornea and dilating eyes with dense cataracts
    - High sensitivity numbers increase the standard deviation and the amount of noise in the data

15. What if the sensitivity is above 94%?

    Image quality is compromised when the sensitivity is too high. Try to keep the sensitivity as low as possible by centering the laser in the pupil, focusing properly (bracketing), hydrating the cornea and dilating eyes with dense cataracts.

16. What can I do if the images are really dark?

    A dark image indicates that the light is either focused too deep in the retina or the image is underexposed due to misalignment of the laser. The light needs to be focused up on the retinal surface or re-aligned in the pupil.

    --------------------------------------------------------------------------------
    - Have patient blink: if image brightens then the cornea was too dry. Either have patient blink more often or instill hydrating drops
    - Ensure camera is within 10mm of patient’s eye
    - Make sure laser is centered in pupil
    - If images have a red and black look rather than a red-orange and yellow look, double check focus settings
    - Adjust or “bracket” the focus to ensure optimal focus
    - If the patient has a small pupil, dilation is recommended to allow the laser light to fully enter the center of the pupil

17. What does the error message “Uncorrected astigmatism or too high too deep” mean?

    This message can indicate several things:

    - Soiled lens - clean the lens with micro-fiber cloth
    - Camera is misaligned - realign camera center in the pupil and ensure distance to eye is within 10 mm
    - Very small pupil - dilate if possible
    - Uncorrected astigmatism
    - Focal plane is too anterior for a deep cup or too posterior for an optic nerve with elevated areas – adjust focus if incorrect
    - In advanced glaucoma cases - the patient’s cup may actually be deeper than 4mm and an image cannot be acquired.

18. Why has the green button at the bottom of the acquisition window turned to red?

    The Red button indicates the laser is off due to an interruption in the communication between the camera and computer.

    --------------------------------------------------------------------------------
    - Green button indicates the laser is on
    - Yellow button indicates laser is paused
    - Check cables to be sure none are loose
    - Exit /Quit the Eye Explorer software and restart Eye Explorer software to reset

19. The images I just acquired do not appear on the screen, where are they?

    As more images are acquired, they are added to the end of the Image Viewing Window. Use the "down" arrows on the screen to scroll down to see your images.

20. What does the box symbol above an image mean?

    Black boxes with 1-2 red boxes above an image indicate that at least one topography failed while being calculated. The “failed topography” symbol indicates that the quality of image is poor.

    --------------------------------------------------------------------------------
    The topography should not be used as a baseline as it will not be included in the Topographic Change (Progression) Analysis.

    When you see this "topography failed" symbol above an image after acquisition, you should immediately re-take the image at that time.

    Topographies that have failed must be excluded from the image series. To do this:

    1. Right-click on the topography with the "failed topography" (black and red boxes) symbol above it.
    2. Left-click on the item "Exclude exam" from the context menu
    3. If a baseline exam, left-click on "OK" to confirm that you want to exclude this exam
    4. An "x" will appear above the image indicating that the patient did have an exam that day, but this exam will not be used for Progression Analysis or Topographic Change Analysis

21. Why would I get a failed topography?

    Failed topographies result from poor-quality images and excessive eye movement.

    --------------------------------------------------------------------------------
    - Re-instruct patient on fixation to minimize movement
    - Some patients might benefit from occluding the eye not being imaged
    - Ensure the cornea is well hydrated
    - Ensure the patient can focus on the fixation target
    - Review movie to check for eye movement
    - Images containing failed topographies cannot be used as baseline images
    - Progression analysis will not use images with failed topographies

22. How do I review the movie of an acquired image?

    Right-click on either the “3D image series” icon or the topography icon and then left-click on the item “show movie” from the context menu.

    --------------------------------------------------------------------------------
    Review movie, checking to be sure optic nerve head (or fovea in Retina acquisition) stays centrally located in all frames.
    Large and frequent eye movements will result in poor-quality images.

23. Why are there black borders around the image

    On a baseline image, black borders can be caused by patient eye movement. On follow-up images, black borders can be a result of eye movement and/or transposition of optic nerve head or fovea.

    --------------------------------------------------------------------------------
    Black borders are normal unless the contour line did not import properly on follow-up images (glaucoma software only).

    - Eye movement should be minimal in saved images
    - Excessive eye movement results in images with increased standard deviations
    - Review movie to check for eye movement
    - Exclude images with excessive eye movement

24. Why has the follow-up image shifted from the center of the screen?

    On follow-up images, a shifted optic nerve head can be a result of eye movement. This shift is normal unless the contour line did not import properly on follow-up images.

    --------------------------------------------------------------------------------
    - Eye movement should be minimal in saved images.
    - Excessive eye movement results in images with increased standard deviations.
    - Review movie to check for eye movement.
    - Exclude images with excessive eye movement

25. Can I change the date of an examination?

    No, examinations are time-stamped by the software at image capture and cannot be altered after acquisition. This is to ensure compliance with Federal guidelines and that patient data is not illegally altered. If the date and time on the computer is not correct, it will incorrectly date acquired images. Immediately amend an correct the computer clock's date and time through the Date and Time option in the Control Panel in the Microsoft Windows software.

26. Can I place contour line points on blood vessels?

    Yes, points can be placed on blood vessels. However, be sure to keep this in mind when reviewing the interactive height display graph. The interactive height display graph depicts the surface height along a cross-sectional line; when at the top of a blood vessel, the surface graph will peak.

27. Does adjusting the pivot point when drawing a contour line affect the measurements?

    No, moving the pivot point will not affect the measurements. Moving the pivot point to the deepest part of the optic nerve head (cup) is sometimes necessary to make the interactive display graph more useful.

28. How do I know if a contour line is placed properly?

    Review the 3D view of optic nerve head. The contour line should be placed on top of the disc margin and should not dip into the cup. The contour line should also be on the inside edge of the scleral ring and not dip into any areas of atrophy.

    Review the individual optical section images and look for change in reflectivity to demarcate the anatomical disc margin (using movie or “Select Series Image” feature).

    Review the horizontal and vertical cross section graphs or the interactive height display graph. The contour line should intersect surface profile at stable retinal surface or edge of the disc. The contour line should not intersect the surface on the slope of the rim.

29. How many points should I use to draw the contour line?

    6 to 8 points should be used to place the contour line, making sure to keep it symmetrical both horizontally and vertically.

    --------------------------------------------------------------------------------
    - Too many points makes it difficult to control the shape of the contour line.
    - Too few points do not accurately define the shape of the disc margin and can make the import of the contour line to subsequent exams difficult.
    - Points can be dragged and manipulated to match the shape of contour-line to the disc margin.
    - The contour line should be symmetrical when disected in half either horizontally or vertically.

30. Can I modify or change a contour line?

    Yes, you may modify the contour line any time you feel it has been placed improperly.

    WARNING! Modifying the contour line on one topography image will modify it on all the current images, including those before and after the image you are working with and each exam must be re-printed.

    WARNING! If a contour line did not import properly, see the FAQ “Why isn’t the contour line importing properly?”

    To modify the contour line:

    Select “Modify Contour” from the Contour menu in the “Show Results” window
    Select “Yes” to the question “Do you really want to modify the contour line?”
    Adjust the points as necessary
    When finished, select “Accept Contour” from the Contour menu
    The contour line has now been modified on all images, and each exam must be reprinted and the patient’s chart updated with the new reports.

31. When should I use the manual alignment feature?

    The Manual Alignment feature should be used when a contour line does not import properly AND quality checks have been performed to determine why the contour line did not import properly. It may also be used when the optic nerve head is not centrally located in both the baseline and follow-up images.

    --------------------------------------------------------------------------------

    Perform the following quality checks before performing the manual alignment procedure:

    - Standard Deviation: Review the standard deviations of both images. Often, you will see a baseline standard deviation over 50 (e.g. 67) and a follow-up image in the 20's (e.g. 21). When there is a quality issue with one of the images, there may not be enough good quality data for the contour line to be imported properly. This is the case if one image is in the 40's, and the next image is in the teens. Standard deviations should be under 50 and/or consistent (e.g. 43 and 41 or 20 and 19, not 43 and 19).
    - Focus and Depth: The focus and depth should be very similar between the two images. If one image was at +8, and now the next image is at a +1, it is possible that the patient has an astigmatism that was not corrected for the first time, and now is being corrected for with astigmatic lenses (or glasses/contacts). A difference of 1-2 diopters with focus is normal, but any difference greater than 2 diopters should be looked at more closely.
    - Eye Movement: While the machine does correct for eye movement, you will want to go back and review the movies for both images and make sure there is not excessive eye movement. Excessive eye movement is defined as the optic nerve head moving more than ¼ of the screen in any direction. You will want to exclude the image if the optic nerve head goes off the screen at any point during the movie.
    - Centering: An image being off-center can cause the contour line to be off. An extreme example of this would be the baseline image is in the lower left hand corner and now the follow-up image is in the upper right hand corner.
    - Contour Line Points: Re-check the contour line. We recommend drawing the contour line with 8 points. If a contour line was drawn with 4 or 5 points, sometimes modifying it to be drawn with 8 points will resolve the problem. If the contour line is modified, remember to reprint all exams and update the patient’s chart (see section “Can I Modify the Contour Line?”).
    After looking at these things, you have two options:

    - If there is a quality issue of any kind (Standard Deviation, Uncorrected Astigmatism, Problem with Focus/Depth, or Excessive Eye Movement), we recommend EXCLUDING the poor quality image. To do this, right-click on the topography of the image in question and select the option "exclude". A small "x" will appear above the image. If it is the baseline image you have excluded, you will need to re-draw the contour line on the follow-up image and re-establish baseline.
    - If the quality of the two images looks good, but there was just enough combination of centering and eye movement to cause the contour line to not import properly, you can MANUALLY ALIGN the follow-up image. To do this, open up the follow-up topography image and select "Align" from the menu bar. From there, follow the directions in your HRT manual for the Manual Alignment feature.

32. Why does the Moorfields classification change if I modify the contour line?

    The Moorfields classification is based on a linear regression analysis between the optic disc area and the log of the neuro-retinal rim. Since the disc area is the area within the contour-line, adjusting the contour line changes the disc area.

    --------------------------------------------------------------------------------
    The contour-line should be placed at the disc margin

33. Why isn’t the contour line importing properly?

    There are several factors that effect contour line import: standard deviations between exams, focus settings between exams, eye movement, centering and the number of points used to draw the contour line.

    --------------------------------------------------------------------------------

    There are several reasons why a contour line will not import properly:

    1. Standard Deviation: Review the standard deviations of both images. Often, you will see a baseline standard deviation over 50 (e.g. 67) and a follow-up image in the 20's (e.g. 21). When there is a quality issue with one of the images, there may not be enough good quality data for the contour line to be imported properly. This is the case if one image is in the 40's, and the next image is in the teens. Standard deviations should be under 50 and/or consistent (e.g. 43 and 41 or 20 and 19, not 43 and 19).
    2. Focus and Depth: The focus and depth should be very similar between the two images. If one image was at +8, and now the next image is at a +1, it is possible that the patient has an astigmatism that was not corrected for the first time, and now is being corrected for with astigmatic lenses (or glasses/contacts). A difference of 1-2 diopters with focus is normal, but any difference greater than 2 diopters should be looked at more closely.
    3. Eye Movement: While the machine does correct for eye movement, you will want to go back and review the movies for both images and make sure there is not excessive eye movement. Excessive eye movement is defined as the optic nerve head moving more than ¼ of the screen in any direction. You will want to exclude the image if the optic nerve head goes off the screen at any point during the movie.
    4. Centering: An image being off-center can cause the contour line to be off. An extreme example of this would be the baseline image is in the lower left hand corner and now the follow-up image is in the upper right hand corner.
    5. Contour Line Points: Re-check the contour line. We recommend drawing the contour line with 8 points. If a contour line was drawn with 4 or 5 points, sometimes modifying it to be drawn with 8 points will resolve the problem. If the contour line is modified, remember to reprint all exams and update the patient’s chart (see section “Can I Modify the Contour Line?”).

    After looking at these things, you have two options:

    1. If there is a quality issue of any kind (Standard Deviation, Uncorrected Astigmatism, Problem with Focus/Depth, or Excessive Eye Movement), we recommend EXCLUDING the poor quality image. To do this, right-click on the topography of the image in question and select the option "exclude". A small "x" will appear above the image. If it is the baseline image you have excluded, you will need to re-draw the contour line on the follow-up image and re-establish baseline.
    2. If the quality of the two images looks good, but there was just enough combination of centering and eye movement to cause the contour line to not import properly, you can MANUALLY ALIGN the follow-up image. To do this, open up the follow-up topography image and select "Align" from the menu bar. From there, follow the directions in your HRT manual for the Manual Alignment feature.

34. Why is there an x or an ! in the center of the image?

    The Moorfields Regression Analysis has calculated a global classification that differs from the classification of each individual sector.

    --------------------------------------------------------------------------------
    Even though each sector has been classified with a green check, yellow exclamation point or red x, the value of the sector is sufficiently close to being borderline. When calculated in combination, this triggers a global classification of borderline or outside normal limits. Classification is then displayed in the center of the image.

35. What are follow-up images compared to?

    Follow-up images are always compared back to the baseline image, and the amount of change between the two images is calculated for the stereometric parameters. For the Topographic Change Analysis (Progression), the last 3 exams are compared back to the baseline to determine if significant change has occurred over time.

    --------------------------------------------------------------------------------
    1. Each stereometric parameter of a follow-up image is compared to each stereometric parameter of the baseline image, and the amount of change between the two images is then calculated.
    - These calculations are listed under the “Change” column of the Standard Reports and in the "Change" sections of the OU Reports
    - To see the change of stereometric parameters between two follow-up images, you must exclude all exams except the two you are interested in comparing.
    2. The TCA anlaysis is automatically printed on the black and white image of the Standard Report and the Standard Report with Moorfields.
    3. The TCA analysis may also be viewed and printed from the "TCA" icon or the "Progression" icon in the Image viewing window.

36. How do I get a progression analysis?

    Topographic Change Analysis (change-probability progression-analysis) automatically calculates once you have acquired 1 baseline image plus 2 consecutive follow-up images.

    --------------------------------------------------------------------------------

    • It is recommended to acquire 3 consecutive follow-up images (4 exams total) to maximize the power of the analysis
    • You may view and print the entire progression analysis by double-left-clicking on the Topographic Change Analysis (TCA) icon in the HRT3/v3.0 software, or on the "Progression" icon in the HRT II software, in the Image Viewing window
    • This analysis automatically is printed on the black and white image of the "Standard Report" and the "Standard Report with Moorfields"
    • With the HRT3/v3.0 Glaucoma Software, you may print out the TCA Progression Report from the "Print" menu of the TCA window
    • With the HRT II Glaucoma software, only the "Print Screen" option is avaialble (hold down the Ctrl key and the P key on the keyboard at the same time, and then press the Enter key)

37. What does each graph measure on the Progression Trend Report?

    The Trend Report displays three different sector combinations:

    1st: Global, Temporal Superior (45º to 90º), and Temporal Inferior (-90º to -45º) octants.
    2nd: Global, Superior (22.5º to 112.5º), and Inferior (-112.5º to -22.5º) sectors..
    3rd: Global, Upper (0º to 180º), and Lower (-180º to 0º) hemispheres.

38. What is the Moorfields Regression Analysis classification based on?

    The Moorfields classification is based on linear regression analysis between the optic disc area and the log of the neuro-retinal rim. It is a measure of one point in time, not a measure of progression, and characterizes the rim only with optic disc size taken into account.

    --------------------------------------------------------------------------------
    - Discriminates between normal and glaucomatous eyes
    - Classification is utilized globally and for each sector
    - When the data is measured, Moorfields compares the rim area and the age-dependent rim area, which is predicted from the actual disc size on the basis of a regression analysis of the normative database.

39. What does “Cup Shape Measure” mean?

    Cup shape measure is a measure of the skew-ness of the frequency distribution of depth values within the contour-line and below the curved surface of the retina. It is an indicator of the overall shape of the cup.

40. What is the Linear Cup/Disc area ratio?

    Linear cup/disc area ratio = average of the cup/disc diameter ratios (square root of cup/disc area ratio). The linear cup/disc ratio should be similar to the clinician’s assessment of cup/disc ratio, as it is an average of all cup/disc ratio measures along all the meridians.

41. Why does the cup/disc ratio not match my clinical assessment of cup/disc ratio?

    The HRT determines the cup as the area below the reference plane and the area within the contour-line as the disc area. A clinician may choose a landmark in the optic nerve head and call the area below it cup while estimating the appropriate disc area for the nerve.

    --------------------------------------------------------------------------------
    The linear cup/disc ratio should be similar to the clinician’s assessment of cup/disc ratio, as it is an average of all cup/disc ratio measures along all the meridians.

42. On a follow-up printout, how do I determine how much change has occurred?

    Each stereometric parameter of a follow-up image is compared to each stereometric parameter of the baseline image, and the amount of change between the two images is then calculated.

    --------------------------------------------------------------------------------
    These calculations are listed under the “Change” column of follow-up Standard Reports, and in the "Change" area of the OU Report.

43. Why do I have a black and white topography image on the follow-up printout?

    The topography image of the optic nerve head in the upper left corner of the Standard Report and the Standard Report with Moorfields is black and white on all follow-up exams, allowing for the Topographic Change Analysis progression data display. These printout cannot be modified.

44. Is there a printout for the Topographic Change Analysis (Progression)?

    The results of the analysis are automatically printed on the follow-up printouts "Standard Report" and the "Standard Report with Moorfields". For the HRT3 and v3.0 Software for the HRT II, a separate TCA Report may be printed from the "Print" menu of the TCA Window.

    --------------------------------------------------------------------------------
    For the HRT II with v1.7 software or earlier:

    - To see the Topographic Change Analysis on screen, double left-click on the “Progression” icon in the image window
    - To print this Topographic Change Analysis screen, press the Ctrl key and the P key on the keyboard at the same time, and then press the Enter key. The Progression window will be printed.

    For the HRT3 and HRTII with v3.0 software for the HRT II:

    - Double-left click on the TCA icon in the Image Window
    - Go up to "Print" on the menu bar and select "TCA"

45. How can I print the 3-D image?

    First, open the 3-D Window by right-clicking on the topography icon in the Image Window and select the menu item “Show 3D”; for the HRT3 and v3.0 software for the HRT II, simply left-click on the "3D" button" in the Results window.

    While viewing the 3-D view window, hold down the CTRL key and P key on the keyboard simultaneously, then press the Enter key. The 3-D view of the topography will print.

46. What is the memory size of an image?

    Image size depends on the number of optical sections acquired for the image. 16 optical sections are acquired per 1 mm of depth, so an image with a depth of 4 mm will have a memory size of ~32MB (uncompressed). All HRT Glaucoma images range in depth from 0.25 - 4 mm. HRT3 Retina and HRT II Retina Upgrade images are acquired at a depth of 4 mm, while HRT II Retina images are acquired at a depth of 2 mm.

47. How often should I archive?

    Archiving protects images from being irretrievably lost due to a system crash. It is recommended to archive daily or at least once per week to protect acquired images.

48. Do I have to manually select which patients to archive?

    No, the Eye Explorer software automatically keeps track of which images have to be archived and therefore images do not have to be manually selected.

49. Do I need to format my new magneto optical (MO) disk?

    Yes, new magneto optical (MO) disks must be formatted through the “Microsoft Windows” software before they can be used to archive data.

    1. Insert the new magneto optical disk with the "B" side facing up
    2. Double-left-click on the "My computer" icon on your Windows desktop
    3. Double-left-click on "Removable disk drive D
    A. If the D-drive Window opens and there are files listed on the disk, do NOT continue with formatting. All patient data will be lost if you proceed to format this disk
    B. If the D-drive Window opens and there are no files listed on the disk, this side of the disk has already been formatted and is ready for archiving
    4. Select “Yes” when asked if you would like to format the disk now
    5. Check the box in front of "FULL"; If you do not have a box that says "Full", check the box in front of "QUICK"
    6. Select "START"
    7. Select “OK” to the warning of the drive being either a large hard disk or a removable disk
    8. Formatting will take only a few seconds
    9. After formatting is complete, select "Close", then press "OK"
    10. If prompted to run a scan disk, select the "x" in the upper right-hand corner to close the Windows help screen; you do NOT have to run a scan disk after the MO has been formatted
    11. Select “Close”
    12. Click on the "x" to close the disk contents screen
    13. Repeat steps 3-12 for side "A" of the MO disk

    --------------------------------------------------------------------------------
    © 2007 Heidelberg Engineering GmbH
    Use of this site signifies understanding and compliance with our terms of use and privacy policy

50. How do I format a new Magneto Optical (MO) disk?

    MO disks may be formatted by going through the “My Computer” icon on the Windows Desktop, with the Windows Explorer or through a desktop shortcut icon entitled “Shortcut to Removable Disk.”
    --------------------------------------------------------------------------------
    Insert the new magneto optical disk with the "B" side facing up
    Double-left-click on the "My computer" icon on your Windows desktop
    Double-left-click on "Removable disk drive D
    If the D-drive Window opens and there are files listed on the disk, do NOT continue with formatting. All patient data will be lost if you proceed to format this disk
    If the D-drive Window opens and there are no files listed on the disk, this side of the disk has already been formatted and is ready for archiving
    Select “Yes” when asked if you would like to format the disk now
    Check the box in front of "FULL"; If you do not have a box that says "Full", check the box in front of "QUICK"
    Select "START"
    Select “OK” to the warning of the drive being either a large hard disk or a removable disk
    Formatting will take only a few seconds
    After formatting is complete, select "Close", then press "OK"
    If prompted to run a scan disk, select the "x" in the upper right-hand corner to close the Windows help screen; you do NOT have to run a scan disk after the MO has been formatted
    Select “Close”
    Click on the "x" to close the disk contents screen
    Repeat steps 3-12 for side "A" of the MO disk

51. How many exams does a Magneto Optical (MO) disk hold?

    - 4.1 GB MO disk holds ~ 150 - 200 exams on each side of the disk. - 2.3 GB MO disk holds ~ 75 - 100 exams on each side of the disk.

52. If the “Shortcut to Removable Disk” is broken or missing, how can I fix it?

    - If the link is broken, first delete the old shortcut by right-clicking on the icon and selecting “Delete”; Select “Yes” to send it to the “Recycle Bin”
    - Go to the “My Computer: icon on the Window’ desktop and open it by double left-clicking on it
    - Select the “Removable Disk” icon by left-clicking once on it
    - Right-click on the “Removable Disk” icon and select “Create new shortcut” from the menu
    - The new shortcut will be placed on the Windows desktop

Question 1