NEARSIGHTEDNESS (MYOPIA)
Throughout the world, there has been a recent increase in the number of people who are nearsighted. Perhaps you know someone who is nearsighted. Maybe you have symptoms of nearsightedness yourself. Chances are becoming more and more likely that you or someone close to you will be affected by this condition. Nearsightedness can dramatically affect quality of life.
What is nearsightedness?
Nearsightedness or shortsightedness is when distance vision is blurred, but near vision is clear. The medical term for nearsightedness is myopia. Myopia is the most common type of vision impairment. It can affect all ages, genders and ethnicities. Common signs of myopia include squinting or sitting too close to see the television. Myopia not only affects clarity of vision, but is associated with other eye complications like retinal pathology. It is very common for myopia to occur and progressively increase during the growing and studying years even until graduation from college.
What causes myopia?
When light is focused by the eye, it is clear when the focal point lands right at the plane of the retina at the back of the eye. If, however, the light focuses before the retinal plane, then it is blurry and we are nearsighted. Two main situations can cause the light to focus before the retinal plane. First, the eye can be too long. Second, the eye’s focusing power can be too strong.
Most children are born a little farsighted (hyperopia). This occurs when the focal point is behind the plane of the retina. As the child grows and develops-especially the first year of life-the length of the eye tends to change to match the focusing power of the eye. This process usually ends with the child seeing clear and the light focusing at the retinal plane (emmetropia). The refractive condition (emmetropia, myopia, or hyperopia) of the eye can still change. In fact, as mentioned earlier, myopia most often begins age 6-10 in childhood.
What really causes myopia?
It appears there are multiple things that contribute to the development of myopia. Remember, most of us are not born nearsighted. First of all, genetics does play a role. Studies conclude that the risk of developing myopia is over six times greater for children with both parents who are nearsighted than if neither parent is myopic.
Ethnicity also has an influence. One study found the prevalence of myopia in the following ethnic groups: Asian 18%, Hispanic 13.2%, African-American 6.6%, and Caucasian 4.4%1. Not only does the genetic makeup influence the development of myopia, but the environment appears to also play a role.
Most notable is the contribution of near work. Higher education and income levels are associated with myopia1. These can both be linked to time spent studying. Also, as noted above, myopia tends to appear at the age most children begin school and often progresses through the studying and growing years even until graduating from college. Although there are multiple theories as to why near work may contribute to nearsightedness, there is not a good consensus at this time.
Another finding associated with myopia is less time spent outdoors5. Past generations spent much more time outdoors than the present. It has been proposed that the increased time indoors is spent doing near activities such as reading and video games. Others feel that the positive effect of being outdoors has to do with vitamin D production and collagen stability leading to less chances of eye lengthening2. This leads into the idea that diet plays a substantial role in the tendency to develop myopia and also the theory of stress having its part.
The bottom line is that there appears to be multiple factors that contribute to the development of nearsightedness. It is likely that all have a role and the more factors present, the higher the chance of developing myopia. So what can be done to prevent myopia and treat it when it does occur?
How can myopia be prevented?
You may have heard “an ounce of prevention is better than a pound of cure.” Well, there are many things that can be done to prevent children from developing nearsightedness. First, encouraging children to play outside for 2-3 hours daily can help decrease the risk2. Be mindful that hats and sunglasses are also wise to protect from the harmful effects of ultraviolet radiation. Because so much of our lives involve near work, good reading habits are also helpful in preventing myopia. Children should hold reading material at least 14 inches away from their eyes. Television viewing should be at least eight feet away.
Next, taking frequent breaks from reading is helpful. Follow the “20/20/20 rule.” This is a reminder that every 20 minutes you should take a 20 second or longer break from reading by looking 20 feet or farther away. Even better is to get up and walk away for a minute or two. Good, upright posture while avoiding reading and studying in bed is also very valuable.
Lastly, there is evidence to suggest that a diet low in refined carbohydrates can assist in preventing myopia. The idea here is that increased levels of sugar and insulin in the blood stimulate tissue growth which may lead to increased eye length2. So there are multiple environmental modifications that can be helpful in preventing nearsightedness. But what about those people that already have myopia? What can be done for them?
How can myopia be treated?
The most common way to treat myopia is through the prescription of glasses or contact lenses. These optical devices move the focal point that is too far forward in the nearsighted eye farther back so it is at the retinal plane. This is a simple and very effective way to treat myopia. However, it is common to have the amount of nearsightedness progressively increase during the growing and studying years. This is disconcerting to the child and parent.
How can myopia be treated and stopped from progressing?
Various theories have been formulated as to how to stop the progression of myopia. Under correction is prescribing glasses or contact lenses leaving the child a little nearsighted. Studies seem to demonstrate a mixed response with some showing decrease in progression and others an increase. Spherical rigid gas permeable contact lenses have also been thought to provide an arrest to myopic progression. Again the results seem equivocal to some slowing of the progression. Bifocals and progressive lenses is another idea that allows the child to see clear in the distance, but take away the eye strain when reading. The results here are mainly positive showing some slowing3. Although some studies point to no effect. Anti-muscarinic eye drops have consistently demonstrated slowing myopic progression for 2 years or more. However, with this option there are adverse side effects, namely light sensitivity and near blur.
Orthokeratology is another option to treat myopia and slow the progression of myopia with less side effects than medication eye drops4. Specialized contact lens retainers that are FDA approved for overnight wear change the shape of the front of the eye while the individual sleeps. The lenses are removed in the morning leaving clear vision without contact lenses or glasses during the day. I have been wearing orthokeratology lenses myself for many years and recommend it as a great option.
So if you have symptoms of nearsightedness, please don’t hesitate to make an appointment at my office in Mesa, Arizona. Don’t suffer through life squinting or worrying that your nearsightedness keeps worsening. Let’s do something about it. We are conveniently located in the east valley serving Mesa, Tempe, Chandler, Gilbert, Apache Junction, and Queen Creek.
References:
- Benjamin, William J. Borish’s Clinical Refraction 2nd Edition. 2006. Elsevier. St Louis, MO. Pgs 34-36; 1442-1443.
- Despotidis, Nicholas. My Children Are Nearsighted Too. Learning Success Center, LLC. USA. Pgs 33-34.
- Walline JJ, Lindsley K, Vedula SS, Cotter SA, Mutti DO, Twelker JD. Interventions to slow progression of Myopia in Children. Cocrane Database Syst Rev. 2011 Dec 7; (12): CD004916.
- Walline JJ, Jones LA, Sinnott LT. Corneal reshaping and myopia progression. Br J Ophthalmol. 2009 Sep; 93(9): 1181-5. Epub 2009 May 4
- Xiang F, Morgan IG, He MG. New perspectives in the prevention of myopia. Yan Ke Xue Bao. 2011. Mar; 26(1): 3-8.