Does looking at a computer damage your eyes?

          The old saying goes that watching too much TV will make your eyes go square. Nowadays, we seem to spend most of our time looking at screens: be it a computer screen at work, a mobile phone screen to make a call or a TV screen to relax. But how bad is looking at screens for our eyes? Is there really any truth behind the old saying?


        According to Dr Blakeney, an optometric adviser to the College of Optometrists, computers will not permanently damage the eyes; however, they can cause strain or exacerbate existing eye conditions. (1)
What problems do looking at computer screens cause?

      People who look at computers frequently, (in particular those that look at a computer for more than three hours a day), (2) may experience symptoms such as:
*Eye discomfort
*Headaches
*Itchy eyes
*Dry or watering eyes
*Burning sensations
*Changes in color perception
*Blurred vision
*Difficulty focussing (1, 2, 3)
*Eyestrain

*Eyestrain is a type of repetitive strain injury (RSI) that is caused by insufficient rest periods, incorrect working conditions and so forth. (2, 4)

*There are many causes of eyestrain. One of these is glare.

*There are two types of glare, direct and indirect. Direct glare is where light shines directly in your eyes; whereas indirect glare is caused by light reflecting off surfaces into your eyes. (3)

*Glare often results from computer screens being too dark or too bright. (2, 5)

*Glare leads to eye muscle fatigue, for the eyes have to struggle to make out the images on the screen. (2)

*Another major cause of eyestrain is the position of the computer screen.

Naturally, the eyes are positioned so that they look straight ahead and slightly down.

If the eyes have to look in a different direction, the muscles have to continually work to hold this position.

Thus, if your computer monitor is positioned incorrectly, the eye muscles must constantly work to hold the eyes in the correct position to view the monitor. (2)

In order to prevent the eyes becoming strained in this way, the top of your computer screen should be no higher than eye level. (3)
Dry eye syndrome
         According to the NHS, using your computer correctly can also help to prevent dry eye syndrome.

Dry eye syndrome is a condition in which the eyes become inflamed due to a lack of tears. This lack of tears is commonly due to a blockage of the oil secreting glands in the eyes.

Although this condition causes discomfort, it does not usually affect vision. (6)
Ways to minimise damage to your eyes caused by computer screens

There are several ways you can minimise the potential damage to your eyes caused by looking at computer screens.

Firstly, it is important to set up your computer screen so that it is in the correct position in relation to your eyes.

As previously mentioned, the top of the screen should be in line with your eye level. In addition, the screen should be placed approximately 18-30 inches from you.

The screen should also be tilted slightly back – between 10 to 15 degrees depending on the person’s particular preference. This is so that you do not receive glare from lights in the ceiling. (3, 7)

Glare can also be avoided by placing blinds over nearby windows, or using a glare screen. (2, 5)

In addition to adjusting the position of your screen, you can also minimise eye problems by simply blinking more frequently.

Many people don’t realise that they actually blink less when they look at a screen. (2)

Blinking is important, however, as it washes your eyes in their naturally therapeutic fluids. (5)

It is also important to take breaks from looking at your screen. One easy way to remember this is to think of 20-20-20. This reminds you that every 20 minutes you should try to look at something 20 feet away for a minimum of 20 seconds. (5)

It is also recommended to take breaks from your screen altogether, in particular every 2 hours. (2)
Can looking at screens improve eyesight?

Despite the potential eye problems caused by looking at a screen too frequently, research carried out in the US has actually found that some screen viewing can be of benefit to the eyes.

Specifically, they found that playing video games can improve vision.

This is because playing video games gives the users chance to improve their contrast sensitivity. (8)

Contrast sensitivity refers to how faded an object can be before it is impossible to differentiate it from the same field of view. It is something that is affected by ageing. (8, 9)

Contrast sensitivity is particularly important for activities such as driving in poor visibility, like in fog or at night. (8)
Overall does looking at computers damage your eyes?

Overall it seems that although looking at a computer may not cause permanent eye damage, it can cause some irritating problems, such as eye strain and dry eyes.

It is also important to remember, that there are many other potential problems associated with sitting down and staring at a computer for long periods of times, such as deep vein thrombosis (DVT). (10)

History of DNA Research

DNA was first isolated by the Swiss physician Friedrich Miescher who, in 1869, discovered a microscopic substance in the pus of discarded surgical bandages. As it resided in the nuclei of cells, he called it "nuclein". In 1919, Phoebus Levene identified the base, sugar and phosphate nucleotide unit. Levene suggested that DNA consisted of a string of nucleotide units linked together through the phosphate groups. However, Levene thought the chain was short and the bases repeated in a fixed order. In 1937 William Astbury produced the first X-ray diffraction patterns that showed that DNA had a regular structure.

In 1928, Frederick Griffith discovered that traits of the "smooth" form of the ''Pneumococcus'' could be transferred to the "rough" form of the same bacteria by mixing killed "smooth" bacteria with the live "rough" form. This system provided the first clear suggestion that DNA carried genetic information—the Avery-MacLeod-McCarty experiment—when Oswald Avery, along with coworkers Colin MacLeod and Maclyn McCarty, identified DNA as the transforming principle in 1943. DNA's role in heredity was confirmed in 1952, when Alfred Hershey and Martha Chase in the Hershey-Chase experiment showed that DNA is the genetic material of the T2 phage.

In 1953 James D. Watson and Francis Crick suggested what is now accepted as the first correct double-helix model of DNA structure in the journal ''Nature''. taken by Rosalind Franklin and Raymond Gosling in May 1952, as well as the information that the DNA bases were paired—also obtained through private communications from Erwin Chargaff in the previous years. Chargaff's rules played a very important role in establishing double-helix configurations for B-DNA as well as A-DNA.

Experimental evidence supporting the Watson and Crick model were published in a series of five articles in the same issue of ''Nature''. Of these, Franklin and Gosling's paper was the first publication of their own X-ray diffraction data and original analysis method that partially supported the Watson and Crick model; this issue also contained an article on DNA structure by Maurice Wilkins and two of his colleagues, whose analysis and ''in vivo'' B-DNA X-ray patterns also supported the presence ''in vivo'' of the double-helical DNA configurations as proposed by Crick and Watson for their double-helix molecular model of DNA in the previous two pages of ''Nature''. In 1962, after Franklin's death, Watson, Crick, and Wilkins jointly received the Nobel Prize in Physiology or Medicine. Unfortunately, Nobel rules of the time allowed only living recipients, but a vigorous debate continues on who should receive credit for the discovery.

In an influential presentation in 1957, Crick laid out the "Central Dogma" of molecular biology, which foretold the relationship between DNA, RNA, and proteins, and articulated the "adaptor hypothesis". Final confirmation of the replication mechanism that was implied by the double-helical structure followed in 1958 through the Meselson-Stahl experiment. Further work by Crick and coworkers showed that the genetic code was based on non-overlapping triplets of bases, called codons, allowing Har Gobind Khorana, Robert W. Holley and Marshall Warren Nirenberg to decipher the genetic code. These findings represent the birth of molecular biology.