Myopia and astigmatism
Last updated date: 03-Mar-2023
Originally Written in English
Myopia and Astigmatism
Our eyes are one-of-a-kind. Our eyes, like snowflakes or fingerprints, have unique forms and proportions. However, most eyes have many characteristics, including elements required for proper vision and eye health. However, some of these distinctions can occasionally alter how our eyes function.
Eyeglasses, contact lenses, and laser eye surgery are all choices for correcting vision.
Astigmatism & Myopia
Myopia (also known as short-sightedness) and astigmatism are examples of refractive errors that produce hazy vision, but they are not the same disorder. Both refractive problems impair your visual acuity; however, myopia produces fuzzy vision of distant objects and astigmatism from any distance. Similarly, distinct features, like as causes and symptoms, come out when examining the differences between myopia and astigmatism.
Many people must wear corrective lenses, such as glasses or contact lenses, to manage vision loss at either long or short distances. Astigmatism, myopia, and presbyopia are the most common causes of these alterations.
Understanding Refractive Errors
A refractive error is a term used to describe eye disorders caused by an uneven eye shape. Each portion of your eye has a certain function. When the form is unusual, the function changes, impacting vision or eye health.
Refractive errors are vision issues caused by the way your eyes refract or reflect light. Light is critical to our eyesight because it travels and is processed by numerous regions of the eye. The outer layer, the cornea, is the first stop on light's long trip through our eyes. A refractive error occurs when there is a mistake in how light passes through the outer layer.
- How do refractive errors happen?
Refractive errors arise when the shape of your eye prevents light from properly concentrating on your retina (a light-sensitive layer of tissue in the back of your eye). The capacity of the eye to refract or concentrate light sharply on the retina in order to see clearly is mostly reliant on three factors:
- Eye length – Light is concentrated before it reaches the retina if the eye is excessively long, resulting in nearsightedness. Light is not focused by the time it reaches the retina if the eye is too short, resulting in farsightedness.
- Curvature of the cornea – Astigmatism occurs when the cornea is not completely spherical, causing the image to be refracted or focused unevenly.
- Curvature of the lens – Nearsightedness occurs when the lens is excessively sharply bent in proportion to the length of the eye and the curvature of the cornea. Farsightedness occurs when the lens is too flat.
What is myopia, and what are its symptoms?
Myopia, often known as short-sightedness, is a disorder that impairs people's ability to perceive distant things. It happens when the eye's length gets overly long, causing light to fall short of the retina. When staring at distant things, this causes hazy vision.
Myopia usually appears between the ages of eight and twelve, and nearly always before the age of twenty. Once myopia develops, it frequently worsens as the body grows. It usually settles down in maturity. During growth phases, changes in glasses or contact lens prescriptions are required.
Myopia is the inability to perceive distant things such as street signs, chalkboards, and television. Myopia is frequently detected during school examinations. Some people are unlucky enough to have both short and long-sightedness as well as astigmatism. This is referred to as myopic or hypermetropic astigmatism.
Fortunately, myopia and hypermetropia are rarely found combined. However, as people age, one eye may become short-sighted and the other long-sighted. Optometrists may leave these individuals with uncorrected vision if they are comfortable without glasses.
As the eye problem becomes more common across the world, numerous optometry offices provide myopia management solutions. Furthermore, controlling myopia in childhood can lessen the likelihood of symptoms worsening and aid enhance lifetime visual quality.
Because astigmatism may coexist with myopia, the symptoms are identical. People with myopia who do not have management options:
- Squinting (to see distances)
- Blurry distance vision
More severe forms of moderate to high myopia, on the other hand, can have a major influence on vision and eye health.
What is Astigmatism, and what are its symptoms?
Astigmatism is a disorder that arises when a defect in your eye's cornea or lens scatters light entering the eye, resulting in foggy vision. Astigmatism is classified into two types: corneal and lenticular. Both may strike anyone at any age.
Astigmatism is fairly frequent, and in the great majority of instances, it is merely due to individual differences. People have diverse shaped corneas, just as they have different shaped feet or hands. It is produced in rare situations by lid swellings such as chalazia and corneal scarring, as well as keratoconus (a rare condition in which the cornea becomes misshapen and pointed rather than smooth and rounded).
Because a perfectly round eye shape is unusual, many people have mild astigmatism. If the problem is slight, you may not even notice it. Those with moderate to severely astigmatic eyes, on the other hand, are prone to have symptoms and will require techniques of visual assistance. Astigmatism symptoms include, in addition to impaired distant or near vision:
- Eye irritation
- Difficulty with night vision
- Squinting (to focus vision)
- Types of Astigmatism
Different types of astigmatism include:
- Corneal astigmatism: This is the most common type of astigmatism.
- Lenticular astigmatism: This type of astigmatism occurs due to changes in the eye’s lens.
- Irregular astigmatism: In this type, the curvature of the cornea is uneven.
Astigmatism must be detected and treated as soon as possible. When evaluating the eyes, an eye specialist may employ the following techniques:
- Visual acuity test: A visual acuity test assesses a person's ability to read letters or characters from a distance. It usually consists of reading lines of letters on a chart. On each line, the letters get smaller and smaller.
- Keratometry: A keratometer is a device that measures the amount of light reflected from the cornea's surface. This gives an eye doctor information about the cornea's shape and curvature.
- Corneal topography: Corneal topography is a form of imaging technique that offers measurements of the cornea in addition to photographs of the cornea. This provides a significantly more thorough evaluation than keratometry.
- Refraction: Refraction tests how the eyes concentrate light by putting a series of lenses in front of the eyes. An eye doctor will inquire as to which lenses improve a person's eyesight.
For most children, the American Optometric Association (AOA) recommends eye exams:
- At 6–12 months
- At 3–5 years
- Before first grade
- Every year after first grade
Children who are predisposed to astigmatism may benefit from more frequent checks. Adults should get an eye checkup every two years until they reach the age of 65, at which point they should have an eye exam every year.
Adults with a higher risk of eye issues should consult an eye doctor at least once a year, regardless of age. Individuals having a history of eye disorders, as well as those with chronic illnesses that might impact the eyes, such as diabetes, fall into this category.
Myopia VS Astigmatism
Myopia frequently emerges in school-age children, whereas astigmatism is present from birth. Myopia often worsens until it stabilizes in early adulthood. While astigmatism is primarily caused by the structure of your eye, myopia is caused by heredity and environmental factors. For example, if one or both parents are myopic, the child is more likely to be as well. Myopia can also occur if the eyes grow somewhat too long.
Astigmatism and myopia frequently coexist, thus if you have astigmatism, you are more likely to be short-sighted. It is also associated with hypermetropia (long-sightedness). Both refractive defects impact how light enters your eyes in this way.
Astigmatism and myopia symptoms are similar in that they both cause hazy or distorted vision. However, myopia occurs when distant things look blurry, and astigmatism makes distinguishing specific forms more difficult. If left untreated, you may develop headaches or eye strain in both circumstances.
Treatment for Astigmatism
If the astigmatism is minor, the ophthalmologist may advise against any treatment. Otherwise, corrective lenses are the standard treatment, however some people may choose laser surgery.
- Corrective lenses for astigmatism
Corrective lenses can help correctly project images onto the retina. These may be in the form of glasses or contact lenses.
- Lenses for astigmatism will need:
- A spherical power, to correct the near or far-sightedness
- A cylinder lens power, to correct the astigmatism
- An axis designation that describes the positioning of the astigmatism
If a person has presbyopia, their lenses will require additional, or add, power to treat this.
- Orthokeratology, or corneal refractive therapy
Orthokeratology is the practice of reshaping the cornea by sleeping with a carefully fitting, hard contact lens. This does not improve vision permanently, but the user may notice that they can see better for at least several hours after wearing it.
Some persons with astigmatism may seek to fix their eyesight through laser eye surgery. Laser in situ keratomileusis is the most prevalent technique (LASIK).
During this operation, the physician creates a thin flap in the cornea with a keratome device or femtosecond laser. They next raise the flap and use a laser to mold the cornea beneath the flap. The surgeon then folds the flap back into place, where it will mend.
LASIK causes dry eyes and changes in vision at first, but these and any other side effects normally go away within a month. Photorefractive keratectomy (PRK) and laser epithelial keratomileusis are two more laser procedures (LASEK).
In PRK, a surgeon removes portion of the cornea's outer protective layer. This might result in moderate to severe discomfort. A laser is then used to sculpt the cornea by eliminating tissue. To manage discomfort, the surgeon will insert a bandage contact lens on the eye while healing.
The surgeon removes a tiny layer of tissue from the cornea during LASEK. The cornea is then reshaped using a laser before the corneal tissue is replaced.
Treatment for Myopia
- Glasses for Correcting Nearsightedness
Eyeglasses are the most popular and easiest approach to cure myopia, especially in youngsters. The angle at which light strikes your retina is corrected by eyeglass lenses. An optometrist or ophthalmologist examines your eyes from various angles and tests your vision using eye charts and concentration exercises to determine the correct prescription for your glasses.
- Contact Lenses for Myopia
Just like with glasses, vision tests and eye examinations establish the prescription for your lenses, and contact lenses correct your vision in the same manner by shifting the direction in which light enters the eye. Natural tears in the eye allow contact lenses to float on the cornea. Because of their closeness to the cornea, the lenses can be much thinner than eyeglass lenses. There are several types of contact lenses:
- Soft lenses: Soft lenses are comprised of malleable soft plastic that readily bends and attaches to the surface of your eye (it can be easier to get used to soft lenses than to rigid ones.) They tend to cover a bigger section of your eye, including the pupil, iris, and white. Some soft lenses are designed to be removed, cleaned, and kept overnight, while others are designed to be discarded after a specified number of wears or time period, ranging from a day to a few weeks.
- Rigid gas-permeable lenses: These are tiny lenses that cover the pupil and extend into the iris. They are constructed of thin, stiff plastic, and when held on a fingertip, they resemble miniature saucers. They float on your tears and transport oxygen to the surface of your eye. Occasionally, a particle of dust or an eyelash slips between the lens and the eye, necessitating the removal, cleaning, and reinsertion of the lens. They are typically not intended to be slept in, however certain extended-wear styles allow for this.
- Correcting Myopia with LASIK
On a daily, temporary basis, both eyeglasses and contact lenses adjust your eyesight. They must be cleaned and/or changed on a regular basis, and they will obstruct your eyesight when not in use. For permanent myopia correction, you should consider refractive surgery, which permanently transforms the eye and typically requires no daily correction afterward. Among the options are:
- LASIK surgery: LASIK (laser-assisted in situ keratomileusis) is the most frequent eye surgical method that can cure nearsightedness and other refractive problems. This procedure alters the shape of the cornea (the circular, front portion of your eye) so that light passes through it and strikes the retina properly.
- PRK: Photorefractive keratectomy is similar to LASIK in that a flap is not excised from the front of the cornea. In this process, the laser immediately corrects the shape of the eye on its surface. It may be a better option for people whose corneas are too thin for LASIK surgery.
- Implantable contact lenses: People with severe nearsightedness may benefit from implanted contact lenses. A prescription lens is implanted either between the cornea and the iris or immediately behind the eye during this process.
- Cataract Surgery: Natural proteins in a person's eye might begin to develop a clump or hazy patch on the natural lens over time. This causes visual distortion and loss in persons over the age of 40. An ophthalmologist/surgeon removes the clouded lens and replaces it with a fresh, clear lens during cataract surgery. To treat myopia in persons with nearsightedness, the new lens can be produced to prescription requirements.
Astigmatism, Hyperopia and Myopia in the premature infant
In the near term, search for Retinopathy of Prematurity (ROP), a disease of the retina's blood vessels (the light sensitive part of the eye). Some newborns' blood vessels are still expanding and must be monitored for the first two to three weeks after discharge, necessitating an eye exam every other day. It is vital that they have constant monitoring to ensure that they do not have any serious diseases that would necessitate laser therapy.
Premature newborns are at risk for myopia, amblyopia, and strabismus in long-term follow-up. For newborns born at fewer than 32 weeks gestation, we recommend a repeat ophthalmologic test at 9 to 12 months. That is not something that the average public does.
Degenerative myopia is a kind of extreme myopia in which the eye condition deteriorate with time. Degenerative myopia can occur at any age, although it is most common between the ages of 30 and 40.
Degenerative myopia, also known as pathologic myopia, affects 3% of the worldwide population. As myopia progresses, the likelihood of having further eye disorders such as:
Ocular diseases associated with degenerative myopia can result in vision loss or poor visual quality.
The most frequent eye issues in youngsters are astigmatism, hyperopia, and myopia. The etiology of refractive errors is typically multifaceted, with genetic (acquired from parents in a number of ways, some of which are connected to other genetic illnesses) and environmental variables both having a role. All three present with vision impairments that cause difficulties seeing that varies in intensity and kind, resulting in visual blurriness, eye strain, and headaches. Eyeglasses, contact lenses, or laser corrective surgery can all help or correct astigmatism, hyperopia, and myopia.