Refractive error

Medical quality assurance by Dr. Albrecht Nonnenmacher, MD at October 1, 2016
StartDiseasesRefractive error

Most eye disorders do not manifest early symptoms. Sometimes they are painless, and a person may see no difference in vision until the disease has become quite advanced. The best way to guard one's eyes is by having regular doctor's visits and eye examinations. Any unfamiliar development in your eyes should be reported to the doctor. The most common vision problems include refractive errors. Refractive errors comprise of farsightedness (hyperopia), nearsightedness (myopia), presbyopia and astigmatism.


Definition & Facts

Refractive errors do occur when the shape of the eye hinder the light from focusing directly on the retina. The length of eyeball changes according to the form of the cornea.

Refraction refers to the bending of light that happens when it passes from one object to another. People see clearly with their eyes when the light rays are bent as they pass the cornea and the lens. When the light is converged on the retina, the retina converts the rays into information which is then sent within the optic nerve to the brain. The brain then performs the work of interpreting the messages into the images we see.

Nearsightedness is a condition that is also referred to as myopia. Myopia occurs when an individual sees the nearby objects clearly, but the distant objects seem blurry. In nearsightedness, the light comes into focus in front of the retina instead of being focused on the retina.

Farsightedness is an ailment that is also named hyperopia. It is a general refractive error that makes the distant objects visible but the near object appears blurred. This condition, however, affects different people differently. Some individuals are incapable of noticing any problem with their vision when they are young. To those individuals with notable farsightedness, vision becomes blurry for objects located at any distance, whether near or far.

Astigmatism is a condition that makes the eye incapable of focusing light evenly onto the retina. The retina is the light-sensitive tissue located at the back of the eye. Astigmatism makes the images appear stretched out and blurry.

Presbyopia is a condition that is age-related, and it makes the eye’s ability to focus difficult. During advanced age, the eye becomes unable to change shape enough to make it possible to view the nearby objects clearly. Presbyopia mostly affects adults who are above the age of 35.

Other refractive errors do affect both adults and children. People whose parents or other family members have refractive errors are more likely to get either one or more of these illnesses.

Symptoms & Complaints

The most common symptom of refractive errors is blurred vision. Other symptoms comprise of haziness, squinting, double vision (diplopia), headache, eye strain, and glare.

Many people with these errors are known to visit eye care professionals with complaints about ocular discomfort or blurred vision.

Individuals with low vision have irreversible vision loss and do not get assistance by using eyeglasses, contact lenses, surgery, or medicine. People affected by poor vision find it hard to perform the routine daily chores like cooking, shopping reading, writing and watching television. These are usually the early warning signs of low vision. People with low vision may be unable to recognize the faces of family members and friends.

If a person finds it difficult to accomplish the things they used to do or if they experience blurred vision, they should consult an eye professional immediately.


In addition to certain environmental factors, there are hundreds of genetic disorders that cause refractory errors. Conditions that cause or are associated with refractory errors include age-related macular degeneration, bulging eyes (exophthalmos), cataracts, cytomegalovirus retinitis, color blindness, crossed eyes (strabismus), diabetic macular edema, glaucoma, eye floaters and eye flashes, keratoconus, lazy eyes (amblyopia), ocular high blood pressure, uveitis, and retinal detachment.

Diagnosis & Tests

Professionals perform diagnosis of refractive errors during a comprehensive dilated eye examination. Tests used to diagnose eye disorders include the following:

Treatment & Therapy

The doctor usually uses eyeglasses, surgery, or contact lenses to correct these refractive errors.

Treatment may also include botulinum toxin injections. The injections are administered to stop muscle spasms for disorders such as hemifacial spasm which impair vision.

Surgery is also performed by specialists to restore straight eye alignment. Laser surgery is done to treat some vision disorders. Many surgical procedures are done in an outpatient setting, without the patient having to spend a night in the hospital.

Prevention & Prophylaxis

Several ways are useful in preventing vision disorders:

  • Healthy diet. Eating the right foods including fruits and vegetables is helpful to the eyes. 
  • Maintaining a healthy weight. Being overweight or obese increases the risk of diseases such as diabetes mellitus that can harm vision.
  • Wearing protective eyewear. One should always protect their eyes by wearing protective gear when working around dangerous chemicals, engaging in construction work, and playing certain sports.
  • Wearing sunglasses: Sunglasses protect the eyes from sun damage.
  • Quitting smoking: Many of the eye diseases have been linked to smoking.
  • Washing hands. Always washing hands thoroughly before putting in contact lenses can help avoid infections.