FAQ Fp-Fit Pro App
FAQ - FP-Fit Pro App
A. GENERAL
1. How can I change the language of the FP-Fit Pro app?
The language of the FP-Fit Pro interface is linked to the language set in your tablet’s settings.
- Go into your tablet’s settings.
- In “General”, click on “Language & Region”.
- In the section “Preferred Languages”, put in first position the language in which you would like your tablet to be displayed, and which will be used for the FP-Fit Pro.
2. How do I ensure that the FP-Fit Pro is updated on a regular basis?
We recommend setting up automatic updates as it ensures the latest version of the app is running on the tablet for you to benefit from the latest features.
- Go into the tablet’s settings.
- In the “App Store”, go to the section “Automatic Downloads” and enable “App Updates”.
- Make sure your tablet is regularly connected to the internet to enable updates.
3. Does the FP-Fit Pro need to be calibrated from time to time?
No, the FP-Fit Pro uses the inclinometer of the tablet and there is no calibration to perform.
4. Do I need to charge the FP-Fit Pro?
The tablet must be charged to run the app and perform measurements.
5. How long are client files stored in the application?
By default, data is stored for 60 months (5 years). However, this setting can be adjusted in the application settings (Settings > FP-Fit Pro), according to the needs of your practice.
B. MEASUREMENTS
1. How precise are the measurements?
The FP-Fit Pro takes measurements to the nearest 0.1 mm. As a comparison, a pupillometer takes measurements to the nearest 0.5 mm.
2. When taking the measurements, what is the optimal position the patient should be in?
In order to obtain optimal measurements, the patient should maintain their natural posture (primary position) meaning their head should not be too raised (military position) or too lowered (slouched position), during the front-view measurements.
This is to ensure that they are taken in relation to exactly how the patient will wear the glasses.
3. What should the patient fix their gaze on when taking far vision measurements?
• Front-view measurements:
Your client should remain in their natural, comfortable posture. Ask your client to look straight ahead in front of them. When they are looking straight ahead, place the tablet’s camera in front of your client at the correct tilt and distance, with the help of the on-screen guidance.
Please note that the tablet’s camera is located in the top corner. Therefore, to place the tablet correctly, hold it slightly to the left to center the camera with the client’s face.
Once the tablet is placed correctly in front of the client, ask them to look at the camera. This ensures they are not influenced to change their head posture or gaze to focus on the tablet’s camera.
• 3/4 view measurements:
The patient must keep their gaze on the tablet’s camera and their head turned at a 20°(±5°) angle.
4. What are the key conditions to have results as accurate as possible?
The following factors should be followed to obtain the best results:
• Light conditions:
- The lighting where the measurements are taken is well diffused (no strong light in front of or behind the patient).
• Frames adjustment and positioning:
- Taking measurements with corrective lenses in place is not recommended. Remove demo lenses whenever it is possible.
- The frames are properly adjusted to the patient’s face before proceeding with the measurements.
• Clip adjustment and positioning:
- Place the clip onto the frames by positioning the central indicator of the clip at the centre of the bridge of the frames.
- The frames must rest against the back of the clip.
- The clip is not touched and/or moved during the measurements process.
• Natural posture of the patient:
- The natural posture of the patient is surveilled at all times by the practitioner: The patient’s posture will greatly impact the measurements: 1° of head / pantoscopic tilt will change the fitting heights by 0.5 mm.
- Refer to question 2 for further details on the patient’s posture.
• Tablet positioning:
- Make sure your client is looking straight ahead, then place the tablet’s camera in front of your patient as vertically as possible and at the correct distance. There is an on-screen guidance to correctly position the tablet.
- Center the tablet’s camera with the client’s face (refer to question 3 for further details).
- The distance is shown in red if you are too close or too far from your patient. If it is green, it is at the correct distance: we recommend being about 60 cm away from your patient.
- Use the green line to place the tablet’s camera at the patient’s sight level. The green line should pass through the patient’s eyes as closely as possible.
- Once the tablet is correctly positioned, the client should look at the tablet’s camera.
• Corneal reflections and boxing:
- Once the measurements photos are taken, validate that the corneal reflections and the clip markers are correctly detected.
- At the Boxing stage, place the boxing lines correctly, meaning on the interior border of the front of the frames, without including the groove depth (bevel).
5. Is it possible to take the measurements of very tall or short patients? What are the height limits for the FP-Fit Pro?
As the FP-Fit Pro is a mobile measurements solution, there is no height restriction. If there is a difference in height between the patient and the ECP, the ECP simply needs to use the green line on the interface as a guide to place the tablet at the correct sight level as mentioned before.
We always recommend taking measurements with the patient standing, in order to take measurements in far vision conditions, however it is still possible to take them seated, which is more practical for taking measurements of children, or patients using a wheelchair. However, the ECP will need to pay particular attention to the patient’s posture.
6. Is it possible to take measurements with the FP-Fit Pro on all patients?
The only cases where it is not possible to take measurements with the FP-Fit Pro are for the following cases:
- If the patient has a nystagmus
- if the patient has a strabismus
- if the patient has a severe ptosis
7. Can measurements be taken with corrective lenses?
Taking measurements with corrective lenses, even of low power, is not recommended due to the prismatic effects that can have an impact on the precision of the measurements.
8. How can the FP-Fit Pro simulate far distance if the client is placed at 60 cm from the tablet?
When the patient is looking at the tablet’s camera, their eyes are converging towards it. By detecting the clip markers on the frames worn, the FP-Fit Pro software will know the exact distance the patient is from the tablet’s camera, and will apply the appropriate corrective calculation to cancel the convergence effects on the measurements. This allows the software to simulate the position of the visual axes in far vision (as if the patient is looking straight ahead far in front of them).
9. The pupillometer gives me accurate readings for monocular PDs. What is the difference with the FP-Fit Pro?
A pupillometer takes monocular PDs in relation to the patient’s facial features, assuming that the frames always sit on the center of the nose. With the FP-Fit Pro, these measurements are taken in relation to the frames being worn, hence if the patient doesn’t have a symmetrical nose, the frames will not necessarily sit exactly on its center. When comparing the two, the FP-Fit Pro takes measurements with the frames worn are therefore more personalized. However, the total PD should not vary between the FP-Fit Pro measurements and the pupillometer, as this is a morphological measurement and does not change if different frames are chosen.
The FP-Fit Pro also takes the measurements in relation to the natural posture of the patient, meaning their head cape and their head tilt. However the head cape of the patient, meaning whether they put forward their right side or left side in their natural position, is neutralized on the FP-Fit Pro, therefore the head cape is set at 0°.
10. Is there any impact on the monocular PD measurements if the central notch of the clip is not properly centered on the frame?
It is always better to center the clip to the frames but there is a tolerance of a few millimeters (around 2 mm on either side of the center of the bridge). The precision of the monocular PD measurements depends on how well the practitioner places the Boxing lines, and not the centration of the clip on the frames.
11. How would one explain the differences between the fitting heights taken with the FP-Fit Pro and manual methods?
There are several advantages of using the FP-Fit Pro compared to a ruler, firstly, because of the patient being in their natural posture, and the 3D reconstruction of the eye-lens-frame structure. Secondly, taking into account the pantoscopic angle to determine the fitting heights, allows for this measurement to be taken with a natural head tilt. Determining the natural head tilt using a ruler is less evident. With the FP-Fit Pro, there is no risk of parallax which is one of the principle factors of error.
When there is a difference between fitting heights taken with a ruler and with the FP-Fit Pro, it generally means that the measurements were not taken in the same conditions.
In order to get the same measurements with both methods we would need to make sure the conditions in which the measurements are taken are the same:
- The head posture of the client is exactly the same for both methods. Head posture greatly influences the fitting heights.
- The frames should sit in the same position and be perfectly adjusted to the patient’s face.
- There are no parallax errors whilst taking the measurements by hand, meaning the optician has to be at the same height as the patient whilst taking the fitting heights.
- The optician takes the fitting height measurement from the centre of the pupil down to the furthest inferior edge of the frame (using Boxing and not Datum).
12. How much is the tolerance of the client’s head angle in the 3/4 view?
The 3/4 view is used to calculate the vertex distance, as well as the wrap and pantoscopic angles. The patient is asked to turn their head at an angle of around 20°, but keep their eyes fixed on the mirror. The tolerance of this angle is between 15° and 25°.
13. Why do we not include the depth of the grooves (bevel) when placing the boxing lines during the boxing stage?
The boxing lines should be placed at the edge of the interior border on the front face of the frames. In placing the boxing lines this way, the grooves of the frames are not taken into account. Once the boxing lines are placed, the optician then chooses what type of frames the patient is wearing. It is at this point that the groove depths are taken into account and the measurements are adjusted according to what type of frames is chosen.
15. How is the vertex distance calculated?
This calculation is based on the stereoscopic principle : 2 angles of view (front- & 3/4-view) of the frame, head and two eye positions provide a 3D reconstitution of the eye-lens-frame structure. Therefore the FP-Fit Pro provides Right and Left vertex distances.
17. The PD measurements do not seem correct. What should I check?
Make sure that all recommendations from point 6 have been followed. Carefully check the position of the corneal reflections (confirm that this is the reflection taken by the FP-Fit Pro and not a parasite lightning).
18. The Fitting height measurements do not seem correct. What should I check?
Make sure that all recommendations from point C-3 have been followed, especially the patient’s posture. The fitting heights on the FP-Fit Pro adhere to international standards of lens manufacturers and are therefore taken at the center of the pupil, in the Boxing frame of reference (and not datum).
Fitting height taken from the center of the pupil
Fitting height taken from the lower edge of the pupil
Boxing Datum
19. If the measurements seem abnormal, are there any warning signs on the results table alerting us to these measurements, and how to remedy?
A warning will appear next to the measurements that seem incoherent or abnormal in terms of value and range. Below is a table to show the ranges of each measurement:
Measurement | Min Value | Max Value | Max Diff |
Mono PDs | 20mm | 38mm | 7mm |
Fitting Heights | 0mm | 50mm | 5mm |
Wrap Angle | 0° | 30° | |
Pantoscopic | 0° | 25° |
20. How can I export the measurements data?
On the results page the measurements can either be:
- Exported to a lens ordering system (1) (to be set in the tablet’s settings of the FP-Fit Pro app).
- Emailed (2) (email address to be set in the tablet’s settings of the FP-Fit Pro app).
- Printed (3) (printer to be linked).
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