What is Nearsightedness?
Evaluating patients for nearsightedness and farsightedness during vision testing is one of the most common things we do. Nearsightedness -- known medically as myopia -- refers to a person who can see objects close at hand clearly in focus while objects in the distance cannot be clearly distinguished or seen at all. It is an extremely common condition and affects approximately one-third of the American population.
How is Nearsightedness Diagnosed?
Myopia is diagnosed through a series of visual tests to measure visual acuity, a measurement of a person's ability to see at a distance and expressed in the form of a fraction. The primary test that indicates a problem is conducted with a distance chart where a patient reads a series of different sized letters or numbers from 20 feet away. This is why a person with "normal" vision is said to have 20/20 vision: they are able to read letters from 20 feet that normally sighted individuals can also read at that distance. Patients who suffer from nearsightedness have visual acuity fractions where the bottom number is greater than 20. For example, someone diagnosed with 20/40 vision would have to stand 20 feet away from the chart to correctly read the letters that a normally sighted person could easily see at 40 feet.
What Causes Nearsightedness?
Research indicates that two factors can ultimately result in myopia. Heredity is known to be a factor. In addition to family background, a person's work or regular hobby can contribute to the condition. This type of occupational or recreational myopia is said to be secondary to the visual stress that prolonged focus on close objects places on the eyes. Diseases such as diabetes and other serious conditions can also cause symptoms of nearsightedness. This is one of the reasons that regular optometric eye examinations are recommended to all individuals with visual problems.
How Is Myopia Treated?
We always take into account a patient's age, degree of myopia, and health history when prescribing a course of treatment. Options include:
- Corrective eyeglasses;
- Corrective contact lenses;
- Corneal refractive therapy or orthokeratology;
- Laser surgery, or
- Visual exercises and therapy for myopia causes by visual stress.
Have you had a vision exam recently?