Astigmatism: Symptoms, Types & Treatment
Astigmatism is a common imperfection in the curvature of your eye that causes light to focus unevenly, resulting in blurry or distorted vision. This condition is often associated with nearsightedness or farsightedness and may be present from birth.
This condition may present with a range of symptoms and is typically diagnosed using a combination of tests and eye examinations. However, there are several treatment options available for this condition, both surgical and non-surgical.
Together with your optometrist, you will be able to choose a treatment plan most suitable to the severity of your condition.
Types of Astigmatism
Astigmatism is categorized based on the site of the irregularity (corneal vs. lenticular) and how it affects your vision (myopic, hyperopic, and mixed). Understanding these differences is important for correct diagnosis and treatment.
Corneal vs. Lenticular
Corneal astigmatism is the most common type of astigmatism and occurs when the cornea has an irregular shape. Instead of being spherical (like a basketball), the cornea is shaped more like a football.
Lenticular astigmatism is less common and is related to an irregular shape of the eye’s lens. The lens, which sits behind the cornea, may have uneven curvature, causing light to be improperly focused on the retina.
Lenticular astigmatism can occur on its own or in conjunction with corneal astigmatism. Both types affect how light is focused onto your retina, which can result in a slight to severe blurring of vision at any distance.
Myopic vs Hyperopic (Near- vs. Far-sighted)
Myopic astigmatism is a condition that occurs when your eyes’ corneas or lenses have a distorted shape, leading to myopia or nearsightedness. In this condition, the light entering your eye focuses before it reaches your retina, making distant objects appear blurry.
Hyperopic Astigmatism, on the other hand, results in hyperopia or farsightedness, meaning you have difficulty focusing on close objects.
Both of these conditions are considered regular astigmatism since the principal meridians are perpendicular to each other, resulting in a well-defined axis. This type is more common and can often be corrected with eyeglasses, contact lenses, or refractive surgery.
Mixed Astigmatism
In this case, you are dealing with both myopia and hyperopia, meaning you have difficulty focusing on objects near or far.
This variety is due to the light focusing both behind and in front of your retina, resulting in some parts of objects appearing clear while other parts are blurry.
Irregular Astigmatism
Irregular astigmatism is less common and occurs when the principal meridians are not perpendicular, characterized by uneven and irregular curvatures in the cornea or lens of the eye. This irregularity may be caused by conditions such as keratoconus or scarring on the cornea.
Correcting irregular astigmatism can be more challenging than regular astigmatism. Standard glasses or contact lenses may not provide optimal correction, and specialized contact lenses or rigid gas-permeable lenses may be necessary.
Causes of Astigmatism
Several factors might contribute to astigmatism. Understanding these causes can provide insight into the condition and help you better understand your options.
Genetics
Genetics influence the shape of your eyes, which in turn may result in the manifestation of astigmatism.
You might have been born with astigmatism or developed it early in life due to inherited genetic characteristics.
Developmental Factors
Astigmatism commonly manifests in infants and young children due to contributing developmental factors. This condition develops due to the shape of the lens or cornea changing shape as the child grows.
This form of ‘infant astigmatism’ is typically mild and can naturally correct itself as the child’s eyes develop over time.
Eye Surgery
Certain surgeries or injuries to the eye might contribute to the development of astigmatism. Incorrect procedures or overcorrection may aggravate the existing condition.
Surgical interventions can alter the shape of your cornea, causing it to become more oblong and lead to refractive errors.
Pressure on the Cornea
Excessive rubbing or pressure on the eyes can distort the curvature of the cornea, resulting in astigmatism.
Remember to exercise caution when rubbing your eyes, apply gentle pressure and don’t rub your eyes excessively.
Eye Trauma
Your eyes can be quite sensitive to damage. Trauma to the eye could potentially lead to astigmatism by causing deformities to your cornea.
Whether it’s from an accident, a sporting injury, or any other physical harm, any force that imposes stress on your eye can disrupt its shape.
Not all traumas, however, guarantee the development of astigmatism. The extent of the deformation of your cornea or lens and how it affects the way your eye focuses light will be the deciding factors.
Reshaped Cornea
Keratoconus is an eye disorder characterized by a gradual thinning and bulging of your cornea, changing it from a round shape to a cone-like one. This disrupts the normal refraction of light, often resulting in the development of astigmatism.
Keratoconus generally emerges in the adolescent years and can progress at a varying rate, leading to light sensitivity, blurry vision, and frequent changes in eyeglass prescription.
Flesh Overgrowth
Pterygium, an eye condition where a pink, fleshy growth develops on the eye, can contribute to astigmatism as the growth disrupts the cornea’s smooth, dome-like structure.
Consequently, the cornea may become rigid or misshapen, resulting in refractive errors and astigmatism.
Corneal Ulcers
Corneal ulcers, often resulting from severe bacterial, viral, or fungal eye infections, can be another cause of astigmatism.
These ulcers create disruptions to the cornea’s smooth surface, leading to scarring that can distort your regular eye shape.
Symptoms of Astigmatism
Astigmatism can present itself in various ways, affecting your vision and quality of life. Recognizing these symptoms can be the first step in managing the condition.
Blurred or Distorted Vision
One of the most common symptoms of astigmatism is blurred or distorted vision. The degree of blur or distortion usually correlates with the severity of your astigmatism.
The blur or distortion might be more noticeable when looking at certain orientations. For instance, vertical lines may appear clear, while horizontal lines might be blurry.
Eye Strain and Fatigue
Astigmatism can cause your eyes to work harder than they normally would, which can lead to eye strain or fatigue.
Attempting to maintain clear vision may tax your eye muscles, resulting in feelings of discomfort or tiredness after extended periods of intense visual activities such as reading, computer work, or driving.
Headaches
Frequent headaches can also be a sign of undiagnosed astigmatism. When your eyes are trying to compensate for the refractive error caused by astigmatism, it puts excessive strain on your eye muscles.
This strain can lead to headaches typically centered around your temple area or behind your eyes.
Difficulty with Night Vision
If you have astigmatism, you may find it challenging to see clearly at night or in low-light conditions. This difficulty might manifest as blurry vision or increased sensitivity to light sources, causing glare or halos around lights.
Driving at night may be made more challenging due to oncoming headlights appearing excessively bright or blurred.
Squinting
Squinting is a common indicator of astigmatism, as it is an unconscious reaction in individuals trying to clear their distorted or blurred vision.
By squinting, you’re essentially changing the shape of your eyes, which may temporarily improve your vision, but this habitual straining can also lead to headaches and eye strain over time.
Eye Irritation
Astigmatism can lead to frequent eye irritation. This irritation may manifest as a constant need to rub your eyes or a feeling of having something in your eye.
These are symptoms of your eyes working harder to compensate for the refractive error, causing some discomfort.
How Is It Diagnosed?
Astigmatism is diagnosed through a series of measurements and tests conducted during an eye exam.
Visual Acuity Test
A visual acuity test is a widely used method to diagnose astigmatism. During this test, you will be asked to read letters from a Snellen eye chart placed at a distance.
This method assesses how clearly you can see at varying distances, which helps detect any refractive errors like astigmatism. If you struggle with seeing certain letters or lines on the chart, it could indicate astigmatism.
Refraction Test
A refraction test, another critical tool for diagnosing astigmatism, helps determine your eye’s refractive error and the right prescription for eyeglasses or contact lenses. This test involves the use of a phoropter, a device fitted with various lenses of different strengths.
Through a trial-and-error process, different lenses are flipped in front of your eyes to measure how they focus light. The lens power that provides the clearest vision becomes part of your prescription.
Keratometry
Keratometry is a test that measures the curvature of your cornea. By reflecting light off your cornea and measuring its reflection, this test can help determine whether your cornea’s shape is causing astigmatism.
The results of keratometry can aid in evaluating the severity of astigmatism and shaping the course of possible treatment options.
Corneal Topography
Corneal topography is a diagnostic tool used in the evaluation of the cornea’s shape and contours. This advanced imaging technique involves creating a detailed three-dimensional map of the cornea’s surface using a specialized machine.
This map can accurately pinpoint irregularities in the curvature of your cornea, indicating if astigmatism is present.
Autorefractors and Aberrometers
Autorefractors and aberrometers are machines that automatically estimate your eye’s refractive error using light that’s reflected through your pupil back out of your eye.
Autorefractors measure how light is affected as it bounces back through your pupil. Aberrometers, on the other hand, measure how light travels through different parts of your eye, generating a detailed map of your eye’s system.
This map can help detect minute aberrations and irregularities, including astigmatism.
Slit-lamp Examination
A slit-lamp examination assists in the diagnosis of astigmatism and other eye conditions by providing an in-depth look at the structures at the front of your eyes.
Using the slit lamp, an instrument combining a high-intensity light source and a microscope, your ophthalmologist will examine your cornea, lens, and anterior chamber in detail.
By illuminating your eye with a thin sheet of light, the slit lamp allows your doctor to view these structures in small sections, which makes it easier to discover any anomalies causing astigmatism.
Ophthalmoscopy
Ophthalmoscopy is a standard procedure that enables an eye care professional to view the back of your eye, including the retina. Examining the shape of the retinal reflection can provide critical clues about the presence and degree of astigmatism.
During ophthalmoscopy, your pupils are dilated to give the professional a broader view of the internal structure of your eyes. By evaluating the way light reflects off your retina, your doctor can assess if there is a refractive error like astigmatism affecting your vision.
Non-Surgical Management of Astigmatism
While astigmatism may seem challenging, there are numerous effective non-surgical options that can help manage this common eye condition.
Eyeglasses
Eyeglasses are the simplest and safest way to correct astigmatism.
These specially crafted lenses can compensate for the irregular shape of your cornea or lens, enhancing your eye’s ability to focus light onto the retina.
Contact Lenses
Contact lenses can provide a more natural vision than eyeglasses as they sit directly on your eyes.
Contacts for astigmatism, known as toric lenses, have varying optical power and corrective adjustments at different orientations. This design allows the lenses to correct the way your eyes bend light and focus it onto the retina.
Orthokeratology
Orthokeratology, also known as Ortho-K, involves the fitting of specially designed gas-permeable contact lenses that you wear overnight.
While you sleep, these lenses gently reshape the front surface of your eye (the cornea) so you can see clearly the following day after you remove the lenses.
This treatment can be an effective temporary solution and is prescribed for correcting mild to moderate irregular astigmatism.
Surgical Treatments for Astigmatism
These procedures aim to modify the shape of your cornea, correcting the refractive errors causing blurred or distorted vision. These procedures can drastically improve visual clarity and quality of life, offering longer-term and potentially permanent solutions.
LASIK Surgery
LASIK (Laser-Assisted In Situ Keratomileusis) is a popular surgical option to correct astigmatism. This refractive surgery involves using a laser to reshape your cornea, allowing your eye to improve the way it focuses light onto the retina.
This procedure is relatively quick, usually taking less than half an hour, and usually results in immediate improvement in vision.
PRK Surgery
PRK (Photorefractive Keratectomy) is another surgical procedure available to treat astigmatism using a laser. Unlike LASIK, however, PRK does not involve creating a corneal flap, making it a suitable option for people with thinner corneas.
Though the PRK recovery period might be slightly longer than LASIK, with added discomfort, it offers the same outstanding results in terms of vision correction.
LASEK Surgery
LASEK (Laser-Assisted SubEpithelial Keratomileusis) combines aspects of both LASIK and PRK to correct astigmatism.
In LASEK, the outer layer of the cornea (epithelium) is loosened and moved aside before a laser reshapes the underlying cornea. The epithelium is then repositioned on the eye’s surface. This shares the healing time of 1-2 weeks to recover with functional vision.
Small Incision Lenticule Extraction
Small Incision Lenticule Extraction, commonly known as SMILE, is a relatively new, modern, minimal-contact surgical approach used for correcting astigmatism and short-sightedness.
During this procedure, a femtosecond laser is used to create a small lenticule (a piece of corneal tissue) that’s removed through a small incision, correcting your cornea’s shape.
This procedure’s minimalistic approach can lead to a shorter recovery time and reduced postoperative discomfort. However, SMILE might not be suitable for everyone, particularly those with high degrees of astigmatism.
Vision will definitely improve, and there is a high chance for you to perform most tasks without corrective glasses.
Epi-LASIK
Epi-LASIK is a variant form of LASIK where only the very thin outer layer of the cornea (epithelium) is lifted to expose the cornea for reshaping.
Unlike LASEK, alcohol, a substance that can harm the epithelium, isn’t used in Epi-LASIK. Instead, a specialized device separates the epithelial sheet from the cornea.
While Epi-LASIK may cause less postoperative discomfort, especially compared to PRK and LASEK due to the absence of alcohol, the visual recovery time is longer than that of LASIK.
Astigmatic Keratotomy
Astigmatic keratotomy (AK) is a surgical procedure used to treat high degrees of astigmatism. This procedure involves making incisions in the cornea to modify its shape and correct the refractive error.
The number, depth, and orientation of the incisions vary depending on the severity and orientation of the astigmatism.
Despite the more advanced procedures available for replacing AK, there are other specialists who prefer AK. It is important to note that the recovery time is much longer, and the outcome of this procedure is considered irreversible, as with cases of overcorrection.
Intraocular Lens Implants
Intraocular lens implants, a standard treatment for cataracts, can also be a potential option for correcting astigmatism.
Specialized toric intraocular lenses have different powers in different meridians of the lens to compensate for the uneven power of the eye, as with astigmatism.
These implants are usually only considered for astigmatism correction in combination with cataract surgery or if one is not an ideal candidate for cornea-altering procedures like LASIK or PRK.
Preventing Astigmatism
It’s worth noting upfront that since astigmatism primarily arises due to genetic factors or eye conditions, prevention is not always an option.
Nevertheless, understanding potential preventive strategies can help you maintain optimal eye health and may minimize the risk of developing or worsening astigmatism.
Regular Eye Examinations
Regular eye examinations are crucial in preventing or slowing the progression of astigmatism.
Early detection of astigmatism can ensure timely treatment, preventing it from worsening or causing other vision-related issues. These eye check-ups also screen for other conditions that might contribute to astigmatism.
Wearing Protective Eyewear
Protecting your eyes from injury could also prevent astigmatism, as certain types of eye injuries can change the shape of your cornea.
Therefore, wearing protective eyewear while engaging in work or sports that could jeopardize your eye safety is essential.
Shield your eyes from harmful ultraviolet (UV) rays by wearing sunglasses that provide UV protection. Prolonged exposure to UV rays may contribute to certain eye conditions.
Managing Eye Strain
Be mindful of eye strain caused by prolonged screen time.
Take regular breaks using the 20-20-20 rule: every 20 minutes, look at an object at least 20 feet away for 20 seconds. This habit can help prevent or slow the onset of refractive issues like astigmatism.
Ensure adequate lighting when reading or working to reduce eye strain and position lighting sources to minimize glare on screens and surfaces.
Proper Contact Lens Care
Improper care or misuse of contact lenses can harm your cornea, potentially leading to astigmatism.
Always follow your eye care professional’s guidelines for cleaning and wearing contact lenses. Avoid overwearing your lenses, and always use sterile lens-cleaning solutions before and after use.
Healthy Lifestyle Choices
Leading a healthy lifestyle can indirectly reduce the risk of astigmatism. Consuming a balanced diet rich in vitamins and antioxidants can support overall eye health. Regular physical exercise can also maintain efficient blood circulation, promoting eye health.
Developing a habit of not smoking can significantly contribute to your eye health, as some studies suggest that smoking may have an adverse impact on your eye’s refractive conditions. Thus, maintaining healthy habits can serve as a supportive measure in ensuring optimal eye health.
Frequently Asked Questions
What is astigmatism, and how does it affect the eyes?
Astigmatism is an imperfection in the curvature of your eye, typically present from birth, which causes an uneven focus of incoming light and can result in blurred or distorted images.
It’s commonly accompanied by nearsightedness or farsightedness. The areas of your eye affected by astigmatism often include the front part of your eye (the cornea) or the lens inside it.
What are the common symptoms of astigmatism?
Astigmatism often presents symptoms such as blurred or distorted vision, eye strain, fatigue, frequent headaches, difficulty with night vision, squinting, and frequent eye irritation.
These symptoms usually correlate with the severity of your astigmatism and are often the result of your eyes working harder to compensate for the refractive error caused by the condition.
What types of tests and examinations are used to diagnose astigmatism?
A combination of tests and examinations are used to diagnose astigmatism. These include a visual acuity test, keratometry, refraction test, corneal topography, the use of autorefractors and aberrometers, slit-lamp examinations, and ophthalmoscopy.
All these tests aid in assessing how your eyes handle light, their refractive errors, and the overall eye structure.
What treatment options are available for astigmatism?
Astigmatism treatment options encompass both non-surgical and surgical methods. Non-surgical treatments include eyeglasses, contact lenses, and orthokeratology.
Surgical treatments involve procedures like LASIK surgery, PRK surgery, LASEK surgery, SMILE, Epi-LASIK, Astigmatic Keratotomy (AK), and intraocular lens implants. The most suitable treatment plan should be discussed with your optometrist.
Can astigmatism be prevented?
Since astigmatism primarily arises from genetic factors or certain eye conditions, completely preventing it may not be possible.
However, incorporating preventive strategies like regular eye examinations, wearing protective eyewear, managing eye strain, proper contact lens care, and leading a healthy lifestyle can help maintain optimal eye health and could minimize the risk of developing or worsening astigmatism.
