Investigating compliance and effectiveness of gamified and conventional vision training for people with convergence insufficiency.

Materials - Computerised virtual reality gaming head set with software for convergence insufficiency training in the form of a game of Snakes. The prescribed training regimen was 20 minutes, 3 times per week for 6 weeks. Participants were instructed to spend half the time in the converged position (where the two eyes are pointed inwards towards the nose, achieved by making the right eye image appear to the left and the left eye image appear to the right) and half the time in the diverged position (where the two eyes are pointed away from the nose achieved by making the right eye image appear to the left and the left eye image appear to the right) and to progressively increase the difficulty level whenever they felt the game became too easy. The task was the game of snakes (where a snake eats items and grows progressively longer and must avoid hitting its own growing body or the wall). The following modification enabled it to train convergence: items were cubes scattered on a sandpit with arrows drawn on them and the snake must eat the cubes from the correct approach direction as indicated by the arrows. Half the arrow was presented to the right eye view and the other half of the arrow was presented to the left eye view. Therefore, the participant must use both eyes to see the whole arrow and to correctly determine the approach angle. For patients who could not view both halves of the arrow, patients could lower the contrast of the half that is seen until the other half is visible, due to decreased suppression of one eye's view over the other eye's view. Patients control the movement of the snake using arrow keys on a regular computer keyboard. Patients change settings also using keys on a regular computer keyboard. Difficulty level was increased in 3 ways. Firstly by the game mechanics (must avoid the gradually increasing body length of the snake), by increasing the velocity of the snake and by increasing the level of convergence and divergence. Adherence was monitored by firstly observing whether the participant could carry out the tasks correctly after training, then assigning unique log ins to each participant and the computer software logging time spent in training and the settings used the participant for training. A phone number of the researcher who did the training was provided in case of difficulties next to the equipment, which was located in a university research laboratory that was left unlocked during business hours. Written instructions were also provided next to the equipment. Treatment assignment was determined by alternating the intervention based on the time of enrolment, however this was not the same as visit 1 hence it was not possible for the researcher assigned to assessing function before and after the intervention to predict the intervention on this basis. Care was taken so that there was no other identifying information of intervention in the record sheets of the participants.