Eye Diseases & Conditions
Refractive Error
Refractive error occurs if the eye cannot focus light properly on the retina. It may cause blurry vision. If your child shows any signs of eye problems, you should take him or her to an eye doctor for a complete eye exam.
There are several types of refractive errors:
Hyperopia (Farsightedness)
Hyperopia (Farsightedness)
In this condition, the eyeball is too short for the normal focusing power of the eye. In children, the lens in the eye accommodates for this error and provides clear vision for distance and usually near viewing, but with considerable effort that often causes fatigue and sometimes crossed eyes (strabismus).
Find out more about hyperopia (farsightedness)
Astigmatism
Astigmatism
Astigmatism results primarily from an irregular shape of the front surface of the cornea, the transparent “window” at the front of the eye. Persons with astigmatism typically see vertical lines more clearly than horizontal ones, and sometimes the reverse.
Find out more about astigmatism
Presbyopia
Presbyopia
Presbyopia is a decreased elasticity of the lens due to advancing age which moves the near point of vision farther from the eye, making it difficult to focus on near objects (farsightedness).
Find out more about Presbyopia
You grew up not being able to see your alarm clock in the morning. When you got your first pair of glasses, you learned that trees had leaves. Going to class got easier since you no longer had to squint to make out the words on the screen. Does this sound like a snapshot of your life? If so, you may have myopia.
What Is Myopia?
Refractive errors are a group of conditions that affect how light refracts or bends when it enters the eye. Myopia is a common type of refractive error, like hyperopia, astigmatism, and presbyopia. Emmetropia is the term used for an eye with no refractive error. Myopic individuals are nearsighted, meaning they can see well up close but have difficulty seeing distant objects. This is in contrast to hyperopia, which causes difficulties with close-up vision. Astigmatism distorts vision at both distance and near. It is often present in combination with myopia and hyperopia. Presbyopia develops later in life, generally in one’s 40s, and causes difficulties with near vision. An eye can only be myopic or hyperopic, not both. However, presbyopia occurs with myopia, hyperopia, or astigmatism. If a person is both presbyopic and myopic, they may have difficulty with both near and far vision.
What Causes Myopia?
Every eye is unique in its shape and dimensions. Myopia, or short-sighted eyes, are typically longer in length than emmetropic (normal) eyes. When distant light enters a myopic eye, it lands in front of the retina, rather than on it. This causes blurry vision, which is correctable with lenses or surgery.
Myopia generally begins in school-age and progresses through early adulthood, at which time it tends to stabilize. However, an atypical set of individuals with degenerative myopia will continue to progress throughout their lives. Also known as pathological myopia, this rare condition results in very high amounts of nearsightedness. Unlike traditional myopia, the degenerative type can lead to significant visual complications. Although many of these complications are treatable, there is still potential for loss of acuity and disability. When we talk about myopia, we are generally referring to the most common type, not its pathological variant.
When researchers have studied what causes myopia, they have found that there are genetic factors at play. If one’s parents are short-sighted, it is more likely that they will be too. There are also environmental myopia causes. Studies have found that people who spend more time indoors have higher rates of myopia advancement. Too much time spent on close work, such as reading and computer use, could contribute to myopia progression. While watching television is not a cause of myopia in and of itself, it does mean spending more time indoors. Spending more time outdoors, in contrast, helps to curb myopia progression. During a child’s development, then, it’s encouraged that they devote sufficient time outdoors.
Sometimes, special contact lenses may be prescribed for children developing myopia as an attempt to slow its progression. An eye drop called atropine may be prescribed as well for this purpose. Eye exercises may be recommended if there is a problem with the focusing system, such as convergence insufficiency, but these do not treat myopia itself. Rather, they help the eyes to work together more effectively, minimizing strain.
Myopia Symptoms
What is the nearsighted vision? It’s blurry at distance. It’s usually clear up close unless there is presbyopia and/or astigmatism as well. Nearsightedness translates to difficulties seeing the television, making out faces at a distance, and experiencing problems with driving, especially at night. One way many people use to get around the blur is to squint their eyes, which helps to temporarily improve clarity. Unfortunately, this could lead to eyestrain and headaches, other common myopia symptoms.
Children may not be able to verbalize their symptoms. It’s important to watch for clues such as eye rubbing, excessive blinking, squinting, or sitting too close to the television.
Astigmatism vs. Myopia
Astigmatism tends to affect vision all around, rather than just at distance like myopia. Many people have both, so it’s not always easy to tell if the blur is caused by astigmatism vs. myopia.
Myopia Treatment
There are many options for treating myopia, the most common being glasses. Nearsighted glasses can sometimes distort vision, especially at higher prescriptions, and therefore many people opt for contact lenses. Most people use the soft type but occasionally they elect for rigid gas-permeable.
Another alternative to myopia glasses is a type of rigid gas-permeable contact lens that is worn overnight. It’s called orthokeratology and it changes the shape of the cornea during the night to minimize the need for glasses during the day.
Can LASIK Fix Nearsightedness?
If you’re looking to permanently treat your nearsightedness, myopia surgery is an option. The most common refractive procedure is laser-assisted in situ keratomileusis or LASIK. In LASIK for nearsightedness, the surgeon creates a thin corneal flap of tissue, lifts it, and applies a laser to flatten the cornea. After this laser ablation is performed according to the exact specifications for the eye, the flap is replaced and smoothed out.
The recovery process is very quick after LASIK, as the flap helps to protect the tissue of the cornea as it heals. Because of the quick and predictable healing after LASIK, both eyes are usually done at the same time. You can expect an improvement in vision almost immediately, with more progress occurring over the course of several days to reach peak clarity.
Before proceeding with LASIK, a measurement of your corneal thickness will need to be performed. You must have sufficient tissue for the LASIK procedure to be safe. If you don’t have enough corneal thickness for LASIK, you may still be a candidate for another procedure called photorefractive keratectomy, or PRK.
Can PRK Fix Myopia?
Some people are better candidates for PRK than they are for LASIK. In PRK, there is no corneal flap created. To start, the outermost corneal epithelial cells are removed. Then, the laser is applied to flatten the cornea. A bandage contact lens is then placed to protect the cornea as it heals.
PRK takes a little longer to heal, so generally, one eye is done at a time. Because PRK doesn’t involve the creation of a flap, less tissue is compromised. This may enable people with thinner corneas who are not good LASIK candidates to be eligible for PRK.
Other Surgical Options
Kraff Eye Institute sure LASIK and PRK are the most common surgical options when it comes to treating myopia, but not every person qualifies for surgery. Luckily there are more and more choices available today. For higher levels of myopia, a Visian ICL procedure or a Refractive Lens Exchange (RLE) may be an option.
While myopia is certainly an inconvenience, it is not a disability! If you’re tired of
blurry vision, talk to your doctor about the best way to correct your nearsightedness. If you’re interested in exploring surgical options to correct your myopia, schedule your complimentary LASIK consultation today.
Dr. Colman R. Kraff
Committed to advancing new technologies in the field of ophthalmology, Dr. Colman Kraff helped to pioneer laser vision correction. In February of 1991, as part of a five-site, U.S., FDA clinical trial team, Dr. Kraff successfully performed the first excimer laser procedures in the Chicagoland area using the VISX Excimer Laser.