Modification of Brain Rhythms on Intensity of Chronic Eye Pain

This study will be conducted using a single-case experimental design (SCED) with multiple baselines across participants. The SCED method involves repeatedly assessing the dependent variables (i.e., pain intensity, pain interference) for each of the participants for the duration of the trial, across all phases. This study will use a design of AB + follow-ups, where 'A' refers to the baseline phase, 'B' is the intervention phase, and there will be two follow-up phases that follow. Four participants will be randomly assigned to different baseline durations of the SCED. In this study, one week (i.e., 7 days of observation) will be considered as a stable baseline. Each baseline phase will be followed by the intervention phase, where participants will complete twenty days of 30-minute EEG neurofeedback sessions over a 4-week period. There will be a 1-week follow-up for each participant immediately after completion of the intervention. Staggered baseline phases will be used under the SCED to ensure that stability is achieved. This will mean that all participants will start their baseline phase on the same day, but the baseline for the first participant will be 7 days, the second participant will have a baseline of 10 days, the third participant will have a baseline of 13 days and the fourth participant will have a baseline of 16 days. Each baseline phase will be followed by the intervention phase, where participants will each complete twenty days of 30-minute EEG neurofeedback sessions over a 4-week period. Following the intervention phase, there will be a 1-week follow up for each participant immediately after completion of the intervention. In addition, a further 1-week follow-up will take place five weeks after completion of the intervention. At the beginning of the baseline phase, each participant will complete self-report questionnaires for the primary and secondary outcomes in the form of a pain journal. Participants will continue to complete this pain journal during the intervention and follow-up phases, in order to monitor for changes in pain intensity and pain interference. Participants will be contacted every day to ensure that they're completing their pain journals at the appropriate times. Each EEG neurofeedback session will be self-administered by participants in their homes. Each participant will complete twenty days of 30-minute EEG neurofeedback sessions over a 4-week period. Each session is comprised of three 5-minute intervals of EEG neurofeedback, with 3-minute breaks in between. Before starting each EEG neurofeedback session, participants will run an impedance check, to ensure the EEG device is positioned correctly and is accurately recording brain activity. The EEG neurofeedback treatment incorporates an EEG headset used to record and capture brain activity to be developed in-house and the interactive gaming interface that has been developed using the Unity3D game engine (Unity Technologies, USA). The neuromodulation treatment protocol targets and suppresses theta and low alpha (4-8 Hz) and high beta (20-30 Hz) frequency band powers and enhances high alpha (9-12 Hz) frequency band powers, which teaches participants to enter a mindful state, dampening pain signalling. During each EEG neurofeedback session, neurofeedback will be performed by recording and capturing the frequency bands of interest (i.e., 4-8 Hz, 9-12 Hz and 20-30 Hz) and relaying the information to the interactive gaming interface, which then provides visual feedback based on the activity recorded: when only one EEG frequency band power is suppressed or reinforced as desired, the game avatar will change colour; when two frequency band powers are activated correctly, the game avatar starts to move forward; and when all three frequency band powers are activated, the gaming background changes colour which indicates that participants have entered a mindful state. Participants will accumulate points for the amount of time they spend in this mindful state (i.e., number of seconds that a participant keeps all three frequency power bands activated). Hence, the aim of the game is to accumulate as many points as possible.