Eye strain, also known as asthenopia, occurs when the eyes become tired from intense use. This can happen after prolonged activities like reading, using a computer, or staring at a smartphone screen. Symptoms may include discomfort, dryness, blurred vision, and headaches. To alleviate eye strain, it's important to take regular breaks using the 20-20-20 rule, which suggests looking at something 20 feet away for 20 seconds every 20 minutes. Proper lighting and maintaining a comfortable distance from screens can also help reduce strain on the eyes.