Frequent blinking is due to either mental stress or dryness or nerve irritation. Please identify the cause and act accordingly.
If he is a regular computer user if so it might be computer vision syndrome please use lubricant eye drops e.g. teardrop 2to3 times daily and rub ocupol d's eye oint twice daily on lids
Next Steps
Follow 20.20.formula ie close ask to close his eyes for 20seconds after every after every 20minutes.keep proper distance between eyes and screen wash eyes with freshwater frequently and don't sit facing towards acorn blowers consume lots of fresh fruit and vegetables and also do cold compresses with ice.