Myopia: A Closer Look At Nearsightedness

What is Myopia?

Myopia is commonly known as nearsightedness It is a very common type of refractive error (a condition of the eye that causes objects viewed by the eye to be out of focus) that affects millions of people worldwide. This condition is becoming more and more common as each year goes by, especially among young children. In order to understand what it really is and how it affects our vision, we need to understand five concepts:
 

1. 1. Light Refraction: When light enters our eye, it bends (refracts) to focus at a certain point (the focal point). In an eye with no prescription (also called emmetropia or an eye with “perfect vision”), light focuses precisely on the back part of the eye called the retina (our eye sensors). When the focal point is precisely on the retina, the image is perfectly in focus and a clear image is sent to the brain.
    

2. 2. The Myopic Eye: Myopic eyes refract light in such a way that the focal point from a distant object is in front of the retina instead of directly on it. Some causes of this are a longer eye axial length (distance from the front to back of the eye), a cornea (the clear, front part of the eye) that is more steeply curved, a combination of the two, and other less substantial factors. Since light from a distant object is not focused directly on the retina, the image sent to the brain will be blurry.
    

3. 3. Near Objects: Objects closer than 20ft are considered near objects. While light from distant objects (objects 20ft or further) focuses directly on the retina in an eye with no prescription, light from near objects focus behind the retina in an eye with no prescription. The myopic eye, on the other hand, focuses light from distant objects in front of the retina and near images further back in the eye. The closer an object is, the further back light is focused in the eye, and the clearer the object gets. If an object is close enough, a nearsighted eye will focus the light from the object directly on the retina, resulting in a perfectly clear image of the object. This is why near objects are much clearer to myopic eyes than distant objects (hence the nickname, nearsighted).
    

4. 4. Accommodation: The action of the eye focusing light closer to the front of the eye is called accommodation. To do this, the muscles of the eye’s focusing system strain and cause light to bend at a steeper angle in the eye, which causes it to focus closer to the front of the eye. The only time a myopic eye needs to accommodate is when an object is held so close that the focal point gets pushed back behind the retina. If the myopic eye accommodates at the perfect amount, it will move the focal point from behind the retina to directly on the retina. A myopic eye with correctly prescribed glasses in front of it is effectively emmetropic (clear for distant objects, but must accommodate to see any near objects). People with myopic eyes usually feel more comfortable taking off their glasses to look at near objects because they must accommodate (strain) less to see near objects without glasses compared to with glasses.
    

5. 5. Pinhole Effect: For the purposes of this article, the concept of the pinhole effect is that as the size of the hole through which light from an object enters the eye decreases, the object comes into better focus. This concept explains why people squint to see better when an image is blurry. The more they squint, the smaller the hole, the clearer the object. Squinting helps people see things more clearly, but it also causes strain on the eyelid and facial muscles responsible for squinting. This commonly leads to eyestrain and even headaches. This is why it is much more common for myopic eyes to experience eyestrain and blur for far objects.

Symptoms and Everyday Challenges

​​​​​Blurry Distance Vision: Seeing distant objects, driving, sports, and outdoor activities may be challenging due to blurred far vision. o While most people with moderate nearsightedness know the benefits of having sharp distance vision, people with mild nearsightedness may not realize how much going from mildly blurry, but manageable vision to sharp vision can make. For example, nighttime glare can be a nuisance and almost dangerous when driving. Many people with nearsightedness who can legally drive without glasses wear prescription glasses at night because it can significantly decrease glare and help them drive more safely.

Eyestrain and Headaches: Frequent eyestrain and headaches can occur from squinting to see distant objects. o Eyestrain can be considered a type of headache since it causes discomfort to the area around the eyes. While eyestrain can be considered a type of headache, it is important to differentiate between eyestrain and other headaches since eyestrain is not a medical emergency while some other types of headaches may be. Eyestrain also may lead to other headaches due to the amount of tension in facial muscles leading to pain in other parts of the head

Uncommon Complications

Eyes with high myopia (prescription of -6.00 or higher) are at an increased risk for some serious conditions. This is why people with high myopia are encouraged to see the eye doctor more frequently and may need more in-depth examination.
 

1. 1. Retinal Detachment: A retinal detachment occurs when the retina detaches from the rest of the eye. Since the retina is the layer of sensors of the eye, a retinal detachment is considered an eye emergency and can lead to permanent vision loss including blindness very quickly. Eyes with high myopia have an increased risk for holes and tears to form in the retina because of their increased axial length. These holes and tears can lead to the retinal detachment. Annual eye exams with dilation are highly recommended for people with high myopia to catch these holes and tears before they advance to a retinal detachment.
    

2. 2. Pathologic Myopia: This occurs when the eye keeps getting longer (increasing axial length) resulting in damage to the structures of the back part of the eye including the retina. This damage can lead to permanent loss of vision that worsens as time goes on. This is rare even in high myopia, but early identification of this condition and close monitoring can decrease chances of permanent vision loss.
    

Causes and Risk Factors

1. 1. Genetics: Myopia tends to run in families. If a person’s parents or siblings have it, they are more likely to develop it.
    

2. 2. Eye Shape: The shape of the cornea and eyeball affects how light refracts. In myopia, the cornea may have a steeper curvature (steeper cornea bends light to a greater degree) and/or the eyeball may be longer.
    

3. 3. Age: As children grow, their eyes naturally elongate. Thus, light focuses closer and closer to the front of the eye. This makes children less farsighted and more nearsighted as they age.
    

4. 4. Environmental Factors: Excessive near work such as reading or screentime and lack of outdoor exposure have been correlated to an increased risk for children to develop nearsightedness.

Corrective Measures

1. 1. Eyeglasses: Correctly prescribed glasses help to focus light onto the retina. This gives much needed relief from blur, eyestrain, and headaches. Glasses also allow patients to optimally enjoy tasks that rely on sharp and comfortable distance vision.
    

2. 2. Contact Lenses: Correctly prescribed contact lenses also help to focus light onto the retina. They perform the same task as glasses while usually giving more comfort. Glasses for myopia are usually heavier and bulkier. Contact lenses do not have any of these drawbacks.
    

3. 3. Refractive Eye Surgery (LASIK/PRK/ICLs): If a myopic patient seeks a more permanent solution, laser surgeries such as LASIK and PRK reshape the cornea to improve focus. Implantation of an ICL improves focus by implanting a synthetic lens in front of the natural lens. There are pros and cons to each surgery, so consult an ophthalmologist to determine if you are a suitable candidate for any of these surgeries.
    

4. 4. Myopia Control: As children with myopia grow up, it is almost guaranteed they will become more nearsighted. As myopia worsens, symptoms and conditions can range from a nuisance to even blindness in very rare situations discussed in the Uncommon Complications section above. There are multiple treatments (myopia control) to minimize progression of nearsightedness in children. These include using special eyedrops, special hard contact lenses, and special soft contact lenses. Each treatment has its pros and cons, so it is very important for parents to be fully educated about each treatment to find the best one for their child. These treatments are highly advisable for children that may be genetically predisposed for high myopia as they may reduce how high their myopia prescription gets as well as reduce risks for the severe complications of high myopia.

How iCare Optometry Can Help

1. 1. Optimal Glasses/Contact Lens Prescriptions: Seeing far away is very important for most people and can help them better enjoy the world as well as function during important tasks. It is usually easy for an Optometrist to help someone see clearly, but clearly without eyestrain is a different story. If glasses are too strong, patients are usually able to see clearly, but have to strain to do so. Our Optometrist takes the time to make sure our patients’ vision is not only clear, but also comfortable.
    

2. 2. Ideal Glasses Options: Glasses lenses for myopia become bulkier, heavier, and minifies the patient’s eyes the more the prescription increases. High Index lens material and/or smaller frames may be recommended to reduce the inconvenience of these issues.
    

3. 3. Refractive Eye Surgery Information: Taking into account the magnitude of the prescription, patient age, and patient goals, we can provide personalized information to help our patients decide if seeing an Ophthalmologist for refractive surgery is the best course of action. We can also go into more detail on the differences between LASIK, PRK, and ICLs.
    

4. 4. Ruling Out Eyestrain: Some patients with chronic headaches are referred to us by their primary care providers (PCPs) to rule out more benign causes of headaches such as distance blur and overcorrected nearsightedness. Before more costly and invasive procedures such as MRIs and CT scans are performed, most PCPs and patients want to see if simple glasses and/or contacts can alleviate headaches. We have helped many patients resolve their headaches caused by eyestrain with our glasses and contact lens prescriptions.
    

For more information on myopia, please visit iCare Optometry at our office in Idaho Falls, Idaho. We work with our patients to understand their visual needs and help them in the best way possible. Please call (208) 522-2839 to discuss any questions with our team of experts or to schedule an appointment today.