Astigmatism
What is Astigmatism?
Astigmatism is the medical term for a type of refractive error that occurs when the cornea (the outer front surface of the eye) or the lens inside the eye is irregularly shaped or non-spherical. This common eye condition causes light rays to bend unevenly as they enter the eye, leading to blurred vision and difficulty seeing at night.
The cornea and lens are generally smooth and evenly curved. This curvature enables light rays to focus directly onto the retina, which is the layer inside your eye that converts light into signals for the brain to interpret.
Nearsightedness (myopia) and farsightedness (hyperopia) are other types of refractive errors that may coincide with astigmatism.
Types of Astigmatism
Astigmatism is often caused by irregularities in the cornea, which is the clear protective outer layer that uses refraction to bend light and bring images into focus. Vision problems may occur if this process is disrupted.
There are three main categories of astigmatism:
- Myopic Astigmatism: Objects look blurry from a distance and clear up close.
- Hyperopic Astigmatism: Objects look blurry up close and clear from a distance.
- Mixed Astigmatism: Objects appear unclear at all distances.
These are the common types of astigmatism:
- Regular Astigmatism: The cornea is not entirely round, which makes the eye curve more in one direction than the other. This distorts vision and makes objects look blurry or stretched.
- Irregular Astigmatism: Similar to regular astigmatism, but the cornea does not curve evenly in one direction or curves in multiple directions.
- Lenticular Astigmatism: Less common than regular or irregular astigmatism, which are collectively known as corneal astigmatism. This occurs when the lens inside the eye has curvature imperfections.
Symptoms of Astigmatism
Blurred vision is the most common symptom of astigmatism. You may also have trouble reading small print up close or recognising road signs from a distance. Other possible symptoms of astigmatism include:
- Eye strain or discomfort
- Difficulty with night vision
- Squinting to see clearly
- Seeing glare and halos around lights at night
- Headaches
What Causes Astigmatism
Astigmatism is hereditary, and you are more likely to develop it if it runs in your family. Other conditions and issues that can cause or worsen astigmatism are:
- Eye injury
- Complications after eye surgery
- Keratoconus, a rare condition that causes the clear tissue on the cornea to thin and bulge out.
How to Diagnose Astigmatism
Astigmatism is usually diagnosed with a comprehensive eye examination, where your eye care specialist will:
- Conduct a visual acuity test to check your vision with a wall chart of letters or symbols.
- Perform a refraction test to measure how much light focuses and bends as it enters your eye.
- Measure the curvature and generate a 3-D map of your cornea using corneal topography.
How to Treat Astigmatism
Astigmatism cannot be cured permanently, but it can be managed or corrected. Your eye care specialist may recommend these treatment options for astigmatism:
- Eyeglasses
- Contact lenses
- Vision correction surgery (LASIK or PRK)
- Cataract surgery (if the patient is diagnosed with both cataracts and astigmatism)
If left untreated, astigmatism can lead to the development of “lazy eye” or amblyopia. This is a condition where the brain begins to favour the stronger eye.
Astigmatism may be present from birth or develop later in life. Young children with biological parents diagnosed with astigmatism may not be aware of their imperfect vision or the symptoms they may experience. Parents should look out for signs such as eye rubbing, squinting to read words, or moving closer or farther to see things clearly.
Astigmatism is a common eye condition that can be treated. This is why it is important to have your eyes checked regularly throughout your life to detect vision changes early on. An eye care specialist like Philips D Izaac can help you detect any vision changes and offer comprehensive care to manage astigmatism. Schedule your appointment with us today, and let’s discuss your next steps if you are at risk of developing astigmatism.
Frequently Asked Questions
How does astigmatism affect night driving?
Astigmatism causes light to scatter inside the eye instead of focusing on a single point on the retina. People diagnosed with astigmatism may see distracting glare or halos around the traffic lights.
How are astigmatism eyeglasses different from other eyeglasses?
The lenses in astigmatism eyeglasses have additional specifications for astigmatism that regular eyeglasses do not have.
How can I know for sure if I have astigmatism?
An optometrist or eye care specialist will conduct a comprehensive eye examination to properly diagnose whether you have astigmatism. If you suspect you have astigmatism, book an appointment with us via our website for a detailed eye examination.
How often should I have my eyes examined?
Regular eye examinations are necessary for maintaining optimal eye health, especially if you are diagnosed with astigmatism. It is recommended to have an eye examination every one to two years, but kindly discuss it with your eye care specialist, as the frequency of visits may be different for everyone’s needs and changes in vision.