Amblyopia and Stereoptic Games for Vision

Stereoacuity refers to the the smallest detectable depth difference that can be seen in binocular vision. When binocular vision is present, the binocular function is the best stereoscopic acuity, measured in arc seconds, achieved for any of the below mentioned tests:

Lang I and Lang II-Stereotest Titmus test Bagolini striated glasses test TNO-Test (TNO: Nederlandse Organisatie voor Toegepast Natuurwetenschappelijk Onderzoek)

Stereoacuity refers to the the smallest detectable depth difference that can be seen in binocular vision. Stereoacuity, expressed in arc sec, will be investigated with a novel, 3D tablet-based test called ASTEROID.

Interocular misalignment refers to the degree to which two eyes's axes are not parallel. It can be measured with the Cover test. Result of Cover test of one eye turning upon covering the other indicates eye misalignment. Red filter involves asking patient to fixate on a white circle at the end of the room and placing a red filter on the patient's fellow eye. If the patient reports a red pinkish light, their eyes are aligned, and they do not have strabismus. The location of the red circle in relation to the white circle will tell the examiner about also the type of the strabismus.

Five built-in tests in the Vivid Vision Home software will be performed to delineate the patient's treatment (in the amblyopia cohort) and to adjust the treatment to the potential improvements, by setting parameters to increase or decrease the amount of blur or occlusion needed for the patient to play the games. In the healthy cohort, the same tests will be done, but they rather aim to accommodate the prisms built in the VR headset to the participants' view.

A Composite Depth Score estimate is measured (1-30) where 0 indicates no stereovision and 30 - 20 arc sec. Patients need to choose which of 4 circular stimuli are floating off the surface, where with each correct response the stimuli become smaller and the disparity decreases.

Five built-in tests in the Vivid Vision Home software will be performed to delineate the patient's treatment (in the amblyopia cohort) and to adjust the treatment to the potential improvements, by setting parameters to increase or decrease the amount of blur or occlusion needed for the patient to play the games. In the healthy cohort, the same tests will be done, but they rather aim to accommodate the prisms built in the VR headset to the participants' view.

Degree of binocular vision is estimated with a virtual Worth 4 Dot test, revealing normal vision, double vision, or suppression of left or right eye.

Five built-in tests in the Vivid Vision Home software will be performed to delineate the patient's treatment (in the amblyopia cohort) and to adjust the treatment to the potential improvements, by setting parameters to increase or decrease the amount of blur or occlusion needed for the patient to play the games. In the healthy cohort, the same tests will be done, but they rather aim to accommodate the prisms built in the VR headset to the participants' view.

The minimal correction needed for patient's ocular posture in a horizontal, vertical and rotational prism is estimated in prism diopters through a Maddox rod like test, where patient aligns vertical and horizontal lines with a spot or a pair of horizontal lines

Five built-in tests in the Vivid Vision Home software will be performed to delineate the patient's treatment (in the amblyopia cohort) and to adjust the treatment to the potential improvements, by setting parameters to increase or decrease the amount of blur or occlusion needed for the patient to play the games. In the healthy cohort, the same tests will be done, but they rather aim to accommodate the prisms built in the VR headset to the participants' view.

The speed of patient's ability to switch between difference vergence demands is estimated in seconds as the participant is aligning a series of shapes or symbols until they make up a single line.

Five built-in tests in the Vivid Vision Home software will be performed to delineate the patient's treatment (in the amblyopia cohort) and to adjust the treatment to the potential improvements, by setting parameters to increase or decrease the amount of blur or occlusion needed for the patient to play the games. In the healthy cohort, the same tests will be done, but they rather aim to accommodate the prisms built in the VR headset to the participants' view.

Participant's maximal horizontal and/or vertical vergence ability is estimated in prism diopters as the the participant is aligning a series of shapes or symbols until they make up a single line.

For this purpose, we will use the MNRead test. The test is administered through an app on an iPad©, electronically recorded (connected to a computer), and is designed to assess reading skills in people with low vision (MNRead, French electronic version, 2016). The MNRead test measures the smallest print readable by the person without making significant errors, as well as the smallest print that the person can read with maximum speed and the maximum reading speed.

Spatial cuing task designed by Folk et al. (1992), adapted to the current project's aims, will be administered separately for the amblyopic/fellow and the dominant eye. Participants search for a target diamond of a predefined color (e.g. blue) in an array of differently colored bars and need to report the bar's orientation (horizontal or vertical) by pressing keyboard keys. On every trial, this search array is preceded by an array where a task-irrelevant visual distractor is present that can have the same or a different color than the target. On 50% of the trials the cues are accompanied by trials.

Selective attention is measured behaviorally by cuing effects, i.e., the difference in speed of responding when the cue and target are in the same versus different locations.

Strength of visual selective attention is measured by the the difference in cuing effects elicited by distractors that matched the color of the target compared to distractors that matched a different color.

EEG will be recorded while participants are doing the adapted Folk et al.'s spatial cuing task (see Outcome 10).

Traditional EEG processes of visual selective attention is measured by the N2pc event-related potential (ERP)component, a traditional marker of visual selective attention. The N2pc is a negative-going voltage deflection observed app. 200-300ms after presentation of the stimulus of interest, larger over electrodes contralateral than ipsilateral to the side of the stimulus.

Strength of visual selective attention here is measured by the difference in the mean amplitude in the N2pc time-window elicited by distractors that matched the colour of the target compared to distractors that matched a different colour.

EEG will be recorded while participants are doing the adapted Folk et al.'s spatial cuing task (see Outcome 10).

Topographic analyses of the EEG/ERPs focus on the reference-independent, multivariate characteristics of the electrical field across the whole scalp. Here, the topographic analyses involve using clustering of the group-averaged EEG/ERP activity over the time-window of the N2pc (see Outcome 11) to identify periods of stable topographic activity (topographic maps). After identification of an optimal number of the topographic maps, they are fit back into single-subject data; parameters like map duration (map onset, map offset) and global explained variance will be analysed.

Strength of visual selective attention here is measured by the difference in the duration of maps present over the N2pc time-window elicited by distractors that matched the colour of the target compared to distractors that matched a different colour.

EEG will be recorded while participants are doing the adapted Folk et al.'s spatial cuing task (see Outcome 10).

Global Field Power (GFP) of the EEG/ERPs is a standard deviation of the moment-by-moment voltage of the electrical field across the whole scalp. Here, the GFP analyses are conducted over the time-window of the N2pc (see Outcome 11) to identify if EEG responses across different conditions were modulated by differences in strength of the response the same, statistically indistinguishable brain network.

Strength of visual selective attention here is measured by the difference in the GFP present over the N2pc time-window elicited by distractors that matched the colour of the target compared to distractors that matched a different colour.

Audiovisual selective attention will be measured, like the visual attention processes, with the Folk et al.'s spatial cuing task (see Outcome 10).

Selective attention is measured by cuing effects, i.e., the difference in speed of responding when the cue and target are in the same versus different locations.

Strength of audiovisual selective attention here is measured by the the difference in cuing effects elicited by colour distractors accompanied by sounds compared to colour distractors presented without sounds.

EEG will be recorded while participants are doing the adapted Folk et al.'s spatial cuing task (see Outcome 10).

Traditional EEG processes of visual selective attention is measured by the N2pc event-related potential (ERP)component, a traditional marker of visual selective attention. The N2pc is a negative-going voltage deflection observed app. 200-300ms after presentation of the stimulus of interest, larger over electrodes contralateral than ipsilateral to the side of the stimulus. The N2pc has been observed during studies of attention to audiovisual stimuli.

Strength of audiovisual selective attention here is measured by the difference in the mean amplitude in the N2pc time-window elicited by colour distractors accompanied by sounds compared to colour distractors presented without sounds.

EEG will be recorded while participants are doing the adapted Folk et al.'s spatial cuing task (see Outcome 10).

Topographic analyses of the EEG/ERPs focus on the reference-independent, multivariate characteristics of the electrical field across the whole scalp. Here, the topographic analyses involve using clustering of the group-averaged EEG/ERP activity over the time-window of the N2pc (see Outcome 11) to identify periods of stable topographic activity (topographic maps). After identification of an optimal number of the topographic maps, they are fit back into single-subject data; parameters like map duration (map onset, map offset) and global explained variance will be analysed.

Strength of audiovisual selective attention here is measured by the difference in the duration of maps present over the N2pc time-window elicited by colour distractors accompanied by sounds compared to colour distractors presented without sounds.

EEG will be recorded while participants are doing the adapted Folk et al.'s spatial cuing task (see Outcome 10).

Global Field Power (GFP) of the EEG/ERP processes is a standard deviation of the moment-by-moment voltage of the electrical field across the whole scalp. Here, the GFP analyses are conducted over the N2pc time-window (see Outcome 11) to identify if EEG responses across different conditions were modulated by differences in strength of the response the same, statistically indistinguishable brain network.

Strength of audiovisual selective attention here is measured by the difference in the GFP present over the N2pc time-window elicited by colour distractors accompanied by sounds compared to colour distractors presented without sounds.

Motor planning and execution deficits will be evaluated during a visually guided reach-to-grasp task at different reaching depths using reflective markers attached to the upper limb.

To evaluate the movement duration, we will calculate the time passed from the start to the end of the movement. We will split it into: reaching phase, manipulating phase and withdrawal phase.

This will be done for 3 conditions: monocular dominant, monocular non-dominant, and binocular.

Motor planning and execution deficits will be evaluated during a visually guided reach-to-grasp task at different reaching depths using reflective markers attached to the upper limb.

To evaluate the reaction time, we will calculate the time passed from the start of the trial (indicated with a custom script) to the start of the movement.

This will be done for 3 conditions: monocular dominant, monocular non-dominant, and binocular.

Motor planning and execution deficits will be evaluated during a visually guided reach-to-grasp task at different reaching depths using reflective markers attached to the upper limb.

To evaluate the smoothness, we will extract the information from the marker placed on the hand and we will calculate its trajectory straightness. The straighther, the smoother the data is, which indicates better motor control. We will split it into: reaching phase, manipulating phase and withdrawal phase.

This will be done for 3 conditions: monocular dominant, monocular non-dominant, and binocular.

Motor planning and execution deficits will be evaluated during a visually guided reach-to-grasp task at different reaching depths using reflective markers attached to the upper limb.

To evaluate the maximum grip aperture, we will extract the difference between the positions of the marker on the index and the marker on the thumb. The maximum difference will be used.

This will be done for 3 conditions: monocular dominant, monocular non-dominant, and binocular.

Motor planning and execution deficits will be evaluated during a visually guided reach-to-grasp task at different reaching depths using reflective markers attached to the upper limb.

To evaluate the time to maximum grip aperture, we will extract the difference between the positions of the marker on the index and the marker on the thumb. The time at which the maximum difference occured will be used.

This will be done for 3 conditions: monocular dominant, monocular non-dominant, and binocular.

Motor planning and execution deficits will be evaluated during a visually guided reach-to-grasp task at different reaching depths using reflective markers attached to the upper limb.

We will use a 128-channel EEG system to record brain activity during this task. We will perform frequency analysis to investigate the power at a specific frequency band between the start signal (custom script) till the start of the movement, time in which the participant should have planned the movement.

This will be done for 3 conditions: monocular dominant, monocular non-dominant, and binocular.

Motor planning and execution deficits will be evaluated during a visually guided reach-to-grasp task at different reaching depths using reflective markers attached to the upper limb.

We will use a 128-channel EEG system to record brain activity during this task. We will perform frequency analysis to investigate the power at a specific frequency band after the start of the movement, time in which the participant is executing the movement.

This will be done for 3 conditions: monocular dominant, monocular non-dominant, and binocular.

Visually evoked potentials (VEPs) will also be measured as an electrophysiological (EEG) index of the integrity (strength) of the visual cortical pathway from the retina to the occipital cortex. VEPs originate from the occipital cortex that receives and interprets visual signals. They consist of a sequence of voltage peaks measured over the occipital electrodes: negative peak (N1), positive peak (P1), negative peak (N2). VEPs will be recorded, for each eye separately, from the responses to the color targets in the selective-attention tasks.

Rasch scores for each questionnaire item will be obtained from published look-up tables available at www.pedig.net, and used to calculate a score for each amblyopic participant (Parent-PedEyeQ for <18-year-olds; adapted Child-PedEyeQ for >18-year-olds) and each treatment arm and group at each visit. Scores will also be converted to a 0-100 scale to aid in interpretation.

Healthy individuals or their parents will not complete this questionnaire.

Child PedEyeQ: Functional Vision, Bothered by Eyes and Vision, Social, Frustration / Worry . Parent PedEyeQ: Impact on Parent and Family, Worry about Child's Eye Condition, Worry about Self-perception and Interactions, Worry about Functional Vision