How your eye works and why it gets tired
The eye works like a camera. The lens bends light and focuses it on the retina, a screen at the back of the eye. The retina sends the picture to the brain.
To see something close, tiny muscles squeeze the lens and make it thicker. To see something far away, the muscles relax and the lens becomes thin. If you look at near things for a long time, the muscles stay tight and get tired. This gives eye strain: dry, itchy or watering eyes, headache and blurry sight.
Doing a lot of close work with little time outdoors is linked to myopia (short-sightedness), where far things look blurry. A doctor can check your eyes and give glasses if you need them.
Habits that protect your eyesight
- Distance: hold books about 30 to 40 cm from your eyes and the screen at arm's length. Sit straight; do not read lying down.
- Light: read in good light that comes from behind or the side. Do not read in the dark or in moving vehicles.
- 20-20-20 rule: every 20 minutes, look at something 20 feet (about 6 m) away for 20 seconds. Blink often.
- Outdoors: spend 1 to 2 hours a day outside in daylight. This helps growing eyes.
- Screens: keep leisure screen time low and stop at least an hour before sleep.
- Care: do not rub your eyes, wash your hands, wear sunglasses in strong sun, and never share eye drops or make-up.
- Food and sleep: eat fruits, green vegetables, carrots and eggs, and sleep 8 to 10 hours.
- Check-ups: test your eyes every year, and as soon as you squint, sit too close to the board or get headaches.
What drugs do: harm to body, brain and life
A drug here means a substance that changes how the body and brain work, such as illegal drugs, tobacco (cigarettes, chewing tobacco), alcohol, and medicines that are misused. Medicines are safe only when a doctor prescribes them and you take the right dose.
- Body: damage to heart, lungs and liver; cancer risk from tobacco; infections from sharing needles.
- Brain: trouble with focus, memory and learning; anxiety, low mood or dangerous behaviour. The teen brain is still growing, so it is hurt more easily.
- Life: falling marks, broken trust in family and friends, money problems and accidents.
- Addiction: the body gets used to the substance and cannot stop easily. Treatment is possible, and asking for help is a sign of strength.
The law and where to get help
In most countries it is a crime to make, sell, carry or use illegal drugs, and the punishment is serious, especially for selling to young people. Rules also limit the sale of tobacco and alcohol to children, and some places ban smoking in public. Laws differ by country, but the message is the same: do not get involved.
If someone you know is using drugs, do not blame them. Talk to a trusted adult, a school counsellor or a doctor. Many countries have free helplines for children and families.
How to say no: refusal skills
Peers may say "try it once" or "everybody does it". Most teenagers do not use drugs, so it is not true. Prepare your reply in advance.
- Say no clearly: "No, thanks." Look at the person and keep your voice calm.
- Change the topic: "Let us play football instead."
- Walk away: leave the place and go to safe people.
- Tell a trusted adult: a parent, teacher or counsellor.
Real friends respect your no. Other helpful habits: sport, hobbies, enough sleep, and talking about stress instead of hiding it.
Try it: a one-week eye diary
For one week, write how many hours you used a screen and how long you were outdoors. Set a timer for 20 minutes during homework and do the 20-second far look. Measure your reading distance with a ruler. Then play the free-play step of the 3D to see your eye-care score. With a friend, act out the four refusal steps for three different pressure lines.
Key formulas and definitions
- Reading distance: about 30 to 40 cm.
- 20-20-20 rule: every 20 min, look 20 feet (6 m) away for 20 s.
- Outdoor daylight: about 1 to 2 hours a day.
- Near vision: lens thick; far vision: lens thin.
- Say no: refuse, change the topic, walk away, tell a trusted adult.
- Medicines: only as a doctor advises.
Worked examples
1. Riya reads for 1 hour 20 minutes without a break. How many 20-second far looks should she have taken?
She should look far once every 20 minutes. 80 ÷ 20 = 4 times, so 4 far looks of 20 seconds each.
2. Karan holds his phone 15 cm from his eyes. What is wrong and what should he do?
15 cm is much closer than 30 to 40 cm. The eye muscles are strained and eye strain or myopia risk goes up. He should hold the phone farther (about 30 to 40 cm), use good light and take breaks.
3. A friend says, 'Just one puff of this, it is harmless.' Write a reply using the refusal steps.
Say no: 'No, thanks, I do not smoke.' Change the topic: 'Are you coming for the match?' Walk away if he insists, and tell a trusted adult such as a teacher if you feel pressured.
Common mistakes
- Thinking only sitting too close to the TV damages eyes. Phones, books and tablets held close also strain the eyes.
- Skipping outdoor time. Daylight outdoors is part of eye protection, not only exercise.
- Believing 'just once' is harmless. Even one try can start a habit and the law still applies.
- Taking medicines of friends or family without a doctor. Misusing medicines is also drug misuse.