Hello,
Does he have any itching in his eyes? Or redness?
If so,then he needs a consultation. If that's not the case, start him on genteal eye drops. Four times a day. Apart from his online classes, avoid giving him screen. (Including tv) . Take him outdoors,a shady place , get him involved in outdoor activities.. anything like cycling or just running around.
Next Steps
wash his eyes twice with cool tap water.
Health Tips
If he has too much light sensitivity,or pain or itchiness, redness in eyes,he needs consultation.