Frequently Asked Questions About HRT3 Retina

1. Can I change the date of an exam?
2. What is the memory size of an image?
3. Do I always need to use the same method to correct for astigmatism?
4. Do I have to enter in the K-values?
5. How do I adjust or bracket the focus?
6. How do I correct for astigmatism?
7. How do I focus an image correctly?
8. How do I get the reflection off of the screen when the patient is wearing glasses?
9. How do I make sure the laser is centered on the pupil?
10. How important is it to have the fovea centered?
11. What can I do if the images are really dark?
12. What is important when acquiring images?
13. What is the proper patient position?
14. When do I need to correct for astigmatism?
15. Why do I need to correct for astigmatism?
16. How high can the Standard Deviation of the Retina Reflectance Map be?
17. What does the box symbol above an image mean?
18. What does the error message “Uncorrected astigmatism or too high too deep”’ mean?
19. Why are there black borders around the image?
20. Why has the follow-up image shifted from the center of the screen?
21. Why would I get a failed topography?
22. Do I have to manually select which patients to archive?
23. How can I print the 3-D image?
24. How do I merge two patient records together or move images to another record?
25. How do I review the movie of an acquired image?
26. The images I just acquired do not appear on the screen, where are they?
27. Why has the green button at the bottom of the acquisition window turned to red?

1. Can I change the date of an exam?

   No, exams are time-stamped by the software 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 on the computer is not correct, it will incorrectly date acquired images. Immediately amend an incorrect date through the date and time control panel in the Microsoft Windows software.

   To amend the date and time on your instrument:

   Double-left-click on the time in the bottom right corner of your Windows desktop
   Correct the date and time
   Click on "Apply"
   Close the Date and Time Properties

2. 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 cup depth, so an images with a depth of 4 mm will have a memory size of ~32MB (uncompressed). All Retina images are acquired at a depth of 4mm.

3. 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.

4. Do I have to enter in the K-values?

   Yes, K-values must be entered once at baseline examination. K-values only need to be updated for exams acquired after the patient has an invasive surgery or any procedure/therapy that will dramatically effect corneal curvature.

   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 acquired HRT images 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.

   If the correct radius of corneal curvature is different from that default value and not entered properly, the measurement results will be not be correct.

   The amount of error in the measurement results increases with increasing deviation of the actual radius of corneal curvature from the assumed default of 7.7 mm.

   Corneal curvature only needs to be entered at baseline and does not have to be updated unless the patient undergoes invasive surgery. After surgery, the corneal curvature may change dramatically, and this can have an effect on the magnification of the acquired images. The c-curve should be updated in the Eye Data window after each invasive surgery the patient undergoes.

   If corneal curvature has not been entered in the past (default value 7.7mm was used), the operator may update the Eye Data page for those examinations with the correct c-curve measurement. However, the topographies will need to be recomputed and the patient’s chart updated with new printouts.

   The average k = (horizontal + vertical k-reading / 2) or alternatively, average k = (flat + steep k-reading / 2) and converted from diopters (dpt) to millimeters (mm)

5. 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

6. How do I correct for astigmatism?

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

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

   If the patient’s cylinder is greater than 1.0 diopter, the operator should select the type of corrective lenses to be used for imaging before continuing on with the acquisition.

   Select one of the following three methods:

   Method 1: Heidelberg Engineering Magnetic Astigmatic Lenses (preferred)

   Check box that says “Astigmatic Lens* [dpt]
   Choose the astigmatic lens by the number that is automatically filled in the box: (+1 to +6) or (-1 to -6). This corresponds to the cylinder power from the patient’s manifest refraction.
   Place this lens on the objective and rotate to the correct axis.
   Read axis from the 12:00 O’clock position on the objective (noted with a white dot).
   Press “OK” and continue on with image acquisition.

   Method 2: Glasses

   If using the patient’s own glasses while acquiring images, check the box that says, “Glasses* [dpt]
   The spherical equivalent (½ cylinder + sphere) will automatically be filled in for the operator, provided data was entered as described above in Step 2.
   Push the glasses as close to the patient’s forehead as possible, tilting the ear pieces up to remove any reflection.
   Press “OK” and continue on with image acquisition.

   Method 3: Contact Lenses

   If using the patient’s own contact lenses, check the box that says, “Contact Lens* [dpt]
   Check the box for either soft or hard contact lenses.
   The spherical equivalent (½ cylinder + sphere) will automatically be filled in for the operator, provided data was entered as described above in Step 2.
   Press “OK” and continue on with image acquisition.

7. How do I focus an image correctly?

   HRT II - Glaucoma & Retina Modules

   If the patient is not wearing glasses or contact lenes, 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 highest part of retinal surface
   Evenly distribute light across 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 leneses, start with the focus dial set at the spherical equivalent (1/2 cylinder + sphere)
   If the patient is wearing glasses or contact leneses, start with the focus dial set to 0 diopters
   Adjust or "bracket" the focus
   Focus on highest part of retinal surface
   Evenly distribute light across 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)

8. 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.

9. 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.

10. How important is it to have the fovea centered?

    It is very important to try to center the fovea at each exam so that the exams may be easily compared over time. The effect of having the fovea off-center in images compounds over time, reducing the data available to perform progression analysis. A fovea not centered properly may affect the ability to align subsequent images.

11. 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

12. 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

13. 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.

14. When do I need to correct for astigmatism?

    Astigmatism measured at greater than 1.0 Diopter must be corrected for by using Heidelberg Engineering’s astigmatic lenses, the patient’s eye glasses, or the patient’s contact lenses. Heidelberg Engineering Astigmatic Lenses are the recommended correction method.

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

    If the patient’s cylinder is greater than 1.0 diopter, the operator should select the type of corrective lenses to be used for imaging before continuing on with the acquisition.

    Select one of the following three methods:

    Method 1: Heidelberg Engineering Magnetic Astigmatic Lenses (preferred)

    1. Check box that says “Astigmatic Lens* [dpt]
    2. Choose the astigmatic lens by the number that is automatically filled in the box: (+1 to +6) or (-1 to -6). This corresponds to the cylinder power from the patient’s manifest refraction.
    3. Place this lens on the objective and rotate to the correct axis.
    4. Read axis from the 12:00 O’clock position on the objective (noted with a white dot).
    5. Press “OK” and continue on with image acquisition.

    Method 2: Glasses

    1. If using the patient’s own glasses while acquiring images, check the box that says, “Glasses* [dpt]
    2. The spherical equivalent (½ cylinder + sphere) will automatically be filled in for the operator, provided data was entered as described above in Step 2.
    3. Push the glasses as close to the patient’s forehead as possible, tilting the ear pieces up to remove any reflection.
    4. Press “OK” and continue on with image acquisition.

    Method 3: Contact Lenses

    1. If using the patient’s own contact lenses, check the box that says, “Contact Lens* [dpt]
    2. Check the box for either soft or hard contact lenses.
    3. The spherical equivalent (½ cylinder + sphere) will automatically be filled in for the operator, provided data was entered as described above in Step 2.
    4. Press “OK” and continue on with image acquisition.

15. Why do I need to correct for astigmatism?

    Astigmatism introduces an optical rotation into the image, affecting image quality. This rotation must be corrected for using astigmatic corrective lenses.

    --------------------------------------------------------------------------------
    In cases of high uncorrected astigmatism, a doubling of the blood vessels may be seen or blood vessels in one area may be out of focus while others are perfectly in focus.

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

    If the patient’s cylinder is greater than 1.0 diopter, the operator should select the type of corrective lenses to be used for imaging before continuing on with the acquisition.

    Select one of the following three methods:

    Method 1: Heidelberg Engineering Magnetic Astigmatic Lenses (preferred)

    1. Check box that says “Astigmatic Lens* [dpt]
    2. Choose the astigmatic lens by the number that is automatically filled in the box: (+1 to +6) or (-1 to -6). This corresponds to the cylinder power from the patient’s manifest refraction.
    3. Place this lens on the objective and rotate to the correct axis.
    4. Read axis from the 12:00 O’clock position on the objective (noted with a white dot).
    5. Press “OK” and continue on with image acquisition.

    Method 2: Glasses

    1. If using the patient’s own glasses while acquiring images, check the box that says, “Glasses* [dpt]
    2. The spherical equivalent (½ cylinder + sphere) will automatically be filled in for the operator, provided data was entered as described above in Step 2.
    3. Push the glasses as close to the patient’s forehead as possible, tilting the ear pieces up to remove any reflection.
    4. Press “OK” and continue on with image acquisition.

    Method 3: Contact Lenses

    1. If using the patient’s own contact lenses, check the box that says, “Contact Lens* [dpt]
    2. Check the box for either soft or hard contact lenses.
    3. The spherical equivalent (½ cylinder + sphere) will automatically be filled in for the operator, provided data was entered as described above in Step 2.
    4. Press “OK” and continue on with image acquisition.

16. How high can the Standard Deviation of the Retina Reflectance Map be?

    Image quality is expressed in terms of the average standard deviation, and should be as low as possible. A Standard Deviation of 50µm or higher indicates that the data should be used with caution. Standard Deviation should also remain consistent throughout the exams (20, 22, 25 not 45, 30, 12).

    --------------------------------------------------------------------------------
    Small and average standard deviation values (<20) indicate excellent image quality
    Topography Standard Deviation Guidelines:
    < 10µm EXCELLENT
    10-20 VERY GOOD
    20-30 GOOD
    30-40 ACCEPTABLE
    40-50 LOOK FOR WAYS TO IMPROVE
    > 50µm LOW QUALITY IMAGE, DO NOT USE AS BASELINE

17. 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

18. 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.

19. 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

20. 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

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. 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.

23. 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.

24. How do I merge two patient records together or move images to another record?

    Duplicate patient records or images acquired under the wrong patient name may be corrected for by using the "Change Patient Feature."

25. 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.

26. 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.

27. 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

Question 1