What Is Myopia?
Nearsightedness (myopia) is a condition in which objects that are far away appear blurred, while near objects can be seen clearly. The ability to see distant objects is usually impaired because a nearsighted person's eyeball is too long or the cornea is too curved.
Who Gets Myopia?
Myopia typically begins at about the age of 6 or 7 years old and increases gradually until early adulthood. The disorder affects more than 40% of people in the U.S., including one third of those 18 years and older.
What Are the Symptoms of Myopia?
Myopia tends to progress over time, but some affected individuals show no signs of myopia at all. Common symptoms include:
1. Difficulty reading close-up objects
2. Decreased near vision
3. Diplopia (fuzziness in the vision when looking at both eyes with both eyes open)
4. Blurry or double vision for short periods of time and/or when blinking
5. Tiredness after long periods of staring at a computer screen or television, including following exposure to bright light from a computer screen or television
6. Intense discomfort after prolonged exposure to near objects (e.g., computers) or to children's toy binoculars, unless wearing corrective lenses with myopic power correction. (These things generally can be corrected with digital contact lenses.) 7. Taste and smell abnormalities due to the overlaying of distant objects
8. Blurred vision, especially after prolonged staring at a computer screen or television (Dizziness, nausea, fatigue).
When to see a doctor?
You should talk to your doctor if you notice any of these symptoms if they are new, or they don't go away after being checked out by a family doctor.
Please remember that eye doctors have different definitions of myopia, so if you have been told that your eyesight is normal when it clearly isn't, then do not assume that you are cured and nothing needs to be done!
What Is the Cause of Myopia?
Knowledge about the cause of myopia is limited. Although it has been known since ancient times that nearsightedness can be induced by prolonged looking at close-up objects and by using non-prescription eyeglasses that cause a convex lens curve in the eye (summarized below), no causes have been identified.
The following factors are known to contribute to myopia:
1. Hereditary factors
2. Poor vision habits (near-point stress, including looking at objects close up for long periods of time without blinking or moving the eyes; far-point stress, such as staring at a computer screen for long periods of time, especially without using corrective lenses)
3. An individual's unique visual environment (e.g., whether reading is encouraged in early childhood and throughout the school years, whether the child participates in sports or other activities in which vision requirements change frequently, and whether the child has access to eye care services).
4. Some studies suggest that exposure to certain endocrine disruptors, including hormones and pesticides, may increase the risk of developing myopia.
5. There appear to be differences in susceptibility to myopia between races, with a higher prevalence in Caucasians and Asians than African-Americans.
6. Moderate -to- high amounts of time spent outdoors are protective against the development of myopia.
Regular eye exams:
Regular eye exams are important to detect and treat eye diseases early before vision is compromised. Your optometrist will be able to provide the best treatment for your needs, based on an assessment of your eyes' current condition and any concerns you may have about your vision, such as ametropia (out-of-focus vision), strabismus (misaligned or crossed eyes), presbyopia (loss of near vision), double vision or amblyopia (weakness in one eye which can also cause double vision).
A diagnosis is typically made based on a patient's symptoms, as well as results from a standard vision test that includes visual acuity testing using the Snellen chart, measurements of eye movement and responses to light stimuli (refraction).
Exposure to risk factors:
While it is generally believed that there are no changes to prevent someone from developing myopia, certain activities may affect the rate at which myopia progresses. Studies suggest that near-point stress and far-point stress increase the development of myopia. Near-point stress (or nearwork) refers to focusing one's eyes on something close up such as a book or computer display for long periods of time without allowing the eyes to relax. Far-point stress refers to staring at something far away, such as an object on the horizon. The risk of progression from myopia to nearsightedness is higher in children and teens who are exposed to a high level of near-point or far-point stress compared to those who have lower levels. Children who spend long hours playing computer games also experience a higher rate of myopia progression than those who spend only short periods of time playing these games.
A variety of treatment options are available to reduce or lessen symptoms related to myopia. Treatment can range from prescription and non-prescription lenses and contact lenses to surgery.
Treatment options include:
Prescription eyeglasses are often used to correct the nearsighted eye. Prescription eyeglasses with a high power of myopia control can help reduce the risk of progression to myopia in many people. Most prescription eyeglasses have a thin lens and are designed to provide correction for nearsightedness without causing discomfort to the eyes. If a person is not wearing prescriptions, consider talking with your optometrist about correcting your vision with an eye drop (e.g., bifocal or progressive lenses).
2. Contact Lenses:
Contact lenses may be used as a way to correct far-point stress while allowing normal near-point vision. A contact lens that provides some correction for distant vision but has little or no correction for near vision is sometimes referred to as a "monovision" contact lens. Monovision contact lenses can be used as an alternative to eyeglasses, or they may be used together with eyeglasses to get the best visual correction possible.
Some people are not happy with their glasses or contact lenses and want a permanent solution for their myopia. Two of the most common surgical options for correcting myopia include LASIK and PRK [photorefractive keratectomy]. LASIK is a laser-assisted in situ keratomileusis (LASIK) procedure. PRK is also a laser procedure for correcting refractive errors in the cornea.
Many people prefer to use eyeglasses instead of contact lenses or other optical devices that require daily cleaning and disinfection, or that only provide the corrections necessary for normal distance vision. Eyeglasses can be worn by themselves or with daily close-up lenses to provide focused near vision or multifocal contact lens therapy (MRt). Both multifocal contact lenses and close-up glasses allow for adequate distance viewing and can be used to effectively prevent refractive errors without causing discomfort.
5. Eye drops (e.g., bifocals or progressive lenses):
Some people may choose to use eye drops, known as bifocals or progressive lenses, to correct nearsightedness. These types of lenses can be added to an eyeglasses prescription to provide no-hassle reading enhancement and distance vision correction combined into one lens for each eye, avoiding the need for multiple pairs of glasses or contacts.
Although many studies have been carried out with conflicting results, a growing body of evidence suggests that myopia, if untreated, may lead to early onset cataracts and retinal detachment.
Lifestyle and home remedies:
- Smoking and caffeine consumption: Cigarette smoking and caffeine consumption have been associated with increasing myopia.
- High levels of indoor light exposure: Some research suggests that exposure to high levels of indoor light may cause myopia.
- Vitamin D deficiency: It has been found that a deficiency in vitamin D may contribute to the development of myopia.
- Excess exposure to nearwork: Much like nearwork can lead to myopic progression, excessive viewing distance for near tasks can, as well.
- Computer usage: According to the American Optometric Association, there has been some evidence that extended periods of computer use may lead to developing myopia. Additional research has disputed this claim, however.
Previous studies have associated the following factors with myopia:
- Age over the age of 20: Myopia begins to increase rapidly after age 20.
- High levels of education: Myopia has been found to be higher in more highly educated groups, particularly college graduates.
- Low consumption of fruits and vegetables: Some research has suggested that low fruit and vegetable consumption could be responsible for increased incidence of myopia.
- Frequent use of video screens as entertainment devices: Research suggests that children and teens who frequently use computer or television screens as entertainment devices may face a higher risk of developing myopia.
- Frequent reading: In some cases, myopia may have been found to be associated with the level of reading done by a student.
- Frequent computer use: Recent studies have suggested that frequent use of a computer can increase one's chances of developing myopia.
- High levels of contact lens use: It has been suggested that the high rates of contact lens use could cause or influence the development and progression of myopia.
- Frequent nearwork: Although research has not consistently verified this link, some studies suggest that the more time spent near work the greater risk for development of myopia.