A student prepares for board exams in New Delhi on Saturday. HT photo Sanjeev Verma
Most students prefer to study at night to avoid any disturbance. However, studying under a lamp for the entire night can result in eye strain. And prolonged eye strain can cause damage to eye muscles and sometimes ruin eyesight.
Eye strain is a common result of reading in dim light. It occurs when the iris expands to take in more light, yet attempts to contract to read text, causing a confusion of signals that hampers vision. Symptoms of eye strain include dry and itchy eyes and blurry vision. Sometimes, the symptoms dissipate shortly after a person stops the activity that caused them, but if the habit persists, permanent damage can occur.
Therefore, reading in dim light should be avoided as it makes the pupils larger to maximise the amount of light entering the eye. This means more light rays enter the eye through the edge of the pupil, which causes the light rays to be refracted differently and create a slightly blurred image at the edges of the retina. This is particularly true for children who do a lot of reading and writing. The eye strain on young eyes can lead to myopia.
Dim light makes it difficult for the eyes to focus and causes short-term eye fatigue. It can also lead to drying of eyes because you blink less often. You tend to squint, and that can give you a headache.
Don’t study in poor light. Use a soft white light that doesn't produce glare and shine directly on your eyes.
Avoid constant long hours at the book in the night. Try the 20-20-20 rule: Every 20 minutes, look away about 20 feet in front of you for 20 seconds. This can help reduce eye strain, especially if you are studying at night. Blinking is also beneficial as it lubricates the eyes. Sometimes being too engrossed in your work makes you forget to blink and rest your eyes
As eyes get fatigued by reading in dim light, overtired eyes can get dry and achy, and may even make your vision seem less clear, but a good night’s rest will help your eyes recover just fine.
If correct vision behaviour is maintained, we can even benefit from challenging activities like reading fine print in dim light.
You can also avoid eye strain when you’re reading by blinking frequently and taking a moment to focus on something out the window or across the room every 15 to 30 minutes.
The author is additional director and head, department of ophthalmology, Fortis Healthcare