More about Atropine Drops

-
 As it is potentially deadly, Atropine derives its name from Atropos, one of the three fates who, according to Greek mythology, choose how a person is to die. Atropine is a tropane alkaloid extracted from the deadly nightshade (Atropa belladonna) and other plants of the family Solanacea. Atropine degrades slowly, typically wearing off in 2 to 3 days. However, its effects can last up to two weeks.

Atropine lowers the “rest and digest” activity of all muscles and glands regulated by the parasympathetic nervous system. This is a part of the nervous system that regulates key involuntary functions of the body, including the activity of the heart muscle, the smooth muscles, including the muscles of the intestinal tract, and the glands. The autonomic nervous system has two divisions, the sympathetic nervous system, which accelerates the heart rate, constricts the blood vessels, and raises blood pressure, and the parasympathetic nervous system, which slows the heart rate, increases intestinal and gland activity, and relaxes sphincter muscles. This occurs because Atropine is a competitive antagonist of the muscainic acetylchloline receptors (Acetylchloline is the main neurotransmitter used by the parasympathetic nervous system). Therefore, it may cause swallowing difficulties and reduced secretions.

Atropine induces mydriasis (paralysis of the iris and focusing system) by blocking contraction of the circular pupillary sphincter muscle, which is normally stimulated by acetylcloline release, thereby allowing the radial pupillary dilator muscle to contract and dilate the pupil of the eye. 


Because of the pupillary dilating effect, ophthalmologists use a weak solution of Atropine to dilate the pupils of patients when they need to have a good look at the retina at the back of the eye. In some cases, Atropine is also used in order to eliminate pseudo myopia and latent hyperopia when eyes are examined. Atropine prevents the eye from focusing and this process is called refraction with cycloplegia. 

Other uses of Atropine are in the treatment of bradycardia (an extremely low heart rate). It is also useful as an antidote for poisoning by oraganophosphate insecticide and nerve gases used in warfare. Troops are likely to be issued Atropine syringes to be used in case they encounter chemical weapons. 

The side effects of Atropine

                  • Temporary stinging in the eyes after the drops are applied
                  • Temporary blurred vision and dilated pupils
                  • Raised pressure inside the eye
                  • With prolonged use, eye irritation and conjunctivitis    (Conjunctivitis is an inflammation of the thin clear tissue that lies over the white part of the eye and lines the inside of the eyelid)
                  • Redness or  swelling of the eye or eyelid 
                  • Dry mouth
                  • Flushing or dryness of the skin
                  • Increased body temperature
                  • Constipation
                  • Difficulty passing urine
                  • Altered heart rate

Atropine use for myopia control

First of all, Atropine is a non-specific muscarinic antagonist. It is unknown at this time how it acts to inhibit myopic progression. One per cent Atropine drops applied to children's eyes every night do indeed slow down the progression of myopia to about 0.33 Diopter a year compared to the normal progression of 1.20 Diopter a year. Recently, several studies, such as ATOM 1 and ATOM 2, (2011), have been published. ATOM 2 investigated the effect of reducing the Atropine concentrate to 0.5%, 0.1% and 0.01%. The results, of course, showed that the lower concentration of Atropine had less effect.

However, such studies usually cover only the effects as long as the drops are applied and important information is left out, such as the Louis Tong, (2008) report that myopia actually rebounds up to two times faster when the Atropine drops are discontinued.

Since Atropine does not prevent myopia we need to consider the benefits and side effects when this drug is applied to otherwise healthy children. There is an ethical issue here.

Atropine is a drug which affects not only the eyes of the child but also the functioning of the parasympathetic nervous system, which slows the heart rate, increases intestinal and gland activity, and relaxes sphincter muscles 

(any of the ring-like muscles able to contract or close a bodily passage or opening. One of the most important human sphincter muscles is the sphincter pylori, a thickening of the middle layer of stomach muscle around the pylorus (opening into the small intestine) that holds food in the stomach until it is thoroughly mixed with gastric juices. Other sphincters are involved in the excretion of waste: the sphincter ani externus keeps the anal opening closed by its normal contraction, and the sphincter urethrae is the most important voluntary control of urination. There is also a sphincter in the eye, the sphincter pupillae, a ring of fibres in the iris that contracts the pupil in the presence of bright light).


As far as controlling myopia is concerned, Atropine only slows down the progression while it is applied. So if a person was -2.00, just as those in the group in the ATOM study were, after two years the Atropine group would have -2.66 myopia (progressing 0.33 a year) and the control group -4.00. However, the crucial fact in order for a parent to make an informed decision is forgotten, namely that myopia tends to progress even faster when the Atropine drops are discontinued (Louis Tong, 2008). So a year after stopping the Atropine treatment the child would most likely be -3.50, not a huge difference considering the hardship the child has been subjected to.


Atropine drops have been used, especially in Taiwan, for years and the number of children prescribed this treatment increased from 36.9% in 2001 to 49.5% in 2007. Yet we are not seeing any significant decrease in the rate of myopia (currently 89%) in Taiwanese children. Atropine is prescribed less in Singapore and rarely in Hong Kong and never in other parts of the world.



What are the effects of Atropine drops?

A child with Atropine in his or her eyes will be light sensitive because of the enlarged pupils allowing 20 times more light into the eyes. Children will need sunglasses when outdoors. They will also look drugged or dazed because of their large frozen pupils. A common result is that children will have difficulty when moving their eyes from far (looking at the blackboard) to near (reading a book or writing) or


accommodative infacility. So to minimise the side effects of the Atropine, doctors will prescribe bi-focals or the more expensive progressive lenses to enable the child to do school work. Singapore, Taiwan and Hong Kong are, of course, famous for the amount of school work that is expected of children. Compared to its temporary benefit, Atropine treatment does not seem worth the hardship the children are subjected to.

What causes myopia?

Myopia is mainly caused by excessive near work such as video game playing and schoolwork. In populations where there is a healthier balance between near and far activities there is less myopia. Children’s distance vision needs to develop first before extensive near work is introduced. So if children are encouraged to look at iPads and video games from early on the natural development of eyesight is disturbed. Native populations in Africa and South America have eyesight that is up to eight times better than what we consider to be normal. A Masai child in Kenya can recognise his friend 1.5 kilometres away. Sailors who spend most of their time on the ocean can see the mast of a ship over the horizon. The rest of the ship is hidden by the curvature of the earth and the horizon is 25 kilometres away.


Therefore, to effectively control myopia, it might be better to send  children out to play more often, and delay school work until their distance vision has fully developed by the age of seven.

Leo Angart

www.vision-training.com

Vision Training for Kids

www.magiceyes.org


Comments

Post a Comment

Popular posts from this blog

More about Astigmatism

-
Image
Eye doctors generally believe that astigmatism is mostly inherited and perhaps partly environmentally caused. They also believe that it does not go away and will probably get worse over time. While the aim of the vision-training astigmatism exercise is to eliminate corneal astigmatism by releasing the tension, it is useful to understand the way astigmatism is corrected with glasses, contact lenses or surgery. First some historical background. Sir Isaac Newton, who himself appears to have been astigmatic, first considered this question of astigmatism in 1727. Seventy years later, in 1801, the renowned scientist Thomas Young investigated astigmatism in detail. Young is reported to have had 1.7 diopters astigmatism. It was Cambridge astronomer Airy (1827) who was the first to correct the astigmatism with a cylindrical lens. However, it was the invention of the keratometer by Helmholtz in 1856 and the treaties of Donders in 1864, “Astigmatism and Cylindrical Lenses,” that put astig
Read more

Principles of Vision Training

-
Image
Principles of Vision Training When it comes to vision training, not all optometrists seems to be on the same page about it. It is admittedly baffling and for many, it is an inference that could make them go out of business. Hundreds of near sighted patients including children are restoring their natural eyesight and omitting their dependence on glasses totally.   Near sightedness or Myopia is an incredibly common medical problem that causes the patient difficulty in seeing objects at a distance. Data shows that the incidence of Myopia has increased in the past few decades. In the 1970s, only 25% of the population had Myopia. But now, about 42% myopics exist.   Myopia is a leading vision problem Myopia can be genetically determined or environmentally determined. Heredity plays an essential role. If the parents have myopia, then the children are at a high risk of inheriting the condition as well.   Additionally, children who spend long durations of time engaged in near s
Read more

More about fluorescent lights

-
Image
Fluorescent light tubes was introduced by General Electric at both the New York and San Francisco World Fairs in 1932. Compact Fluorescent Light CFL was also developed by General Electric in 1973, but the 25 million dollars needed the build a factory was considered too expensive at the time so it was not produced outside the laboratory. The design was eventually copied by others. In 1995, helical CFLs, were manufactured in China and became commercially available. Since that time, their sales have steadily increased.   In 2005 the EU began phasing out incandescent light bulbs in favour of CFL’s the US followed in 2014. The rationale is energy sawing since the CFL are using less energy than the old-fashioned Edison incandescent lamp. However, the newer solid state Light Emitting Diodes L.E.D. technology is far more energy efficient. L.E.D lights use 80% less energy and has a lifespan approaching 40 years of continuous use and has no mercury. Naturalness of fluore
Read more