Admin Settings

The Administrator Settings are designed to be accessed by users who want to look "under the hood" of Ocula. The default Administrator Settings are set in such a way that it makes it difficult for a user to make a mistake when conducting an exam, for example environmental conditions such as light and sound are measured to ensure that they do not interfere with the accuracy of the exam. Therefore, interfering with these settings is not advised unless you have a specific goal in mind that can only be attained by changing these advanced user settings.

Noise Check

Environmental noise can impact pupil size. This can interfere with the exam, causing accuracy issues. Therefore, Ocula measures environmental noise both before and during the recording. If the set Upper limit measured in decibels (dB) is breached, it will not be possible to start a recording, or an in progress recording will be aborted. With this setting, you can disable Noise Check before recording and/or during recording, or change the threshold noise level in decibels at which the Noise Check will trigger.

Minimum starting pupil width

In order for a PLR (pupillary light reflex) test to be meaningful, the pupil response to light must be large enough that a difference can be measured. Therefore, if the environment is too bright, the starting pupil width will be too small for a large enough difference in response to light to be measured. When the Min. pupil size setting is enabled, if the measured pupil size is less than the specified width in millimetres (mm), Ocula will not allow an exam to begin. With this setting, you can disable the minimum pupil width requirement, which allows the exam to begin in any lighting condition. Furthermore, with this setting you can change the threshold pupil width at which the minimum starting pupil width will trigger.

Pupil Detection Sensitivity

Eye position

Improper positioning of the eyes relative to the device taking an Ocula exam can cause accuracy issues. When the eye positioning check is enabled, Ocula will not allow an exam to begin unless the eyes have been correctly positioned in the yellow boxes on the exam screen. By disabling this setting, it will be possible to begin an exam regardless of eye placement.

Machine Learning

The Confidence threshold percentage refers to the minimum level of confidence the machine learning model should use to identify the pupil. You may notice that the model labels many round things on the examination screen, this is okay because of all the occurrences of a pupil the model identifies, it will only use the two it is most confident about to extrapolate exam results. Increasing the Confidence threshold value will result in less potential pupils being identified and decreasing the Confidence threshold value will result in more potential pupils being identified.

Graphing

By default Ocula smoothes out the recorded pupil measurements via a low pass filter to increase data readability. By disabling Low pass filter smoothing, the data will be presented unfiltered. Alternatively, the strength of the filter can be increased or decreased by modifying the value of the Low pass filter smoothing setting (where 1 is strongest and 0 is weakest).

Torch Brightness

Torch Brightness refers to the brightness of the 5 second torch exposure which occurs during the Ocula exam.

Background Torch:
In some cases, the subject's pupil is difficult to detect due to very low contrast between the pupil and iris. To help with this, you can enable a background light to illuminate before the stimulus torch begins and continues until after the stimulus ends. Torch Level: sets the intensity from 0-5% (defaults to 0, which means no background light). Torch delay (ms): The time at which the background torch illuminates after the recording starts. Torch duration (ms): The time for which the background torch is illuminated.

We recommend a torch level of 2% to enable Ocula to detect the pupil, but not evoke a full pupillary light reflex. However, this is strongly dependent on the colour of the iris and the room illumination. You may need more or less background light for the best results.
Background torch delay defaults to 500ms and duration to 14500ms so that it's effects on pupil size are observable when compared with ambient room illumination.

The total time of the background delay + duration must be less than the total time of the exam (17000ms).

For comparison, the stimulus torch turns on with a 2000ms delay and 5000ms duration

Severity Threshold

Severity Threshold is used to determine the severity of an out or range biomarker. Out-of-range biomarkers are either marked yellow or red. The default Severity Threshold value is 33%, which is one standard deviation from normal. Green, in-range results are within one standard deviation of the mean. When the Severity Threshold value is 33%, out of range results marked yellow are within 2 standard deviations and results marked red are outside of 2 standard deviations. Increasing the Severity Threshold value will mark more out of range results as yellow, whereas decreasing the Severity Threshold will mark more out of range results as red.

Iris Diameter

The Iris Diameter value is used to perform a pixel to millimetre calculation, based on which all measurements taken by Ocula are referenced.