Refractive error is among the most prevalent eye disorder worldwide. It causes blurred vision and can significantly affect your quality of life. Refractive errors are the reason why people need to wear eyeglasses or contact lens to see clearly.
What are Refractive Errors?
When we look at an object, we don’t often think about the complex process that happens within our eyes to bring that image into clear focus. In simplest terms, our eyes work a bit like a camera: Light from the object enters our eyes and is bent (or “refracted”) by the cornea and lens so that it focuses directly on the retina, the screen at the back of the eye. The retina then sends this image to our brain via the optic nerve. And voila! We see the object in front of us.
But what if this process isn’t working quite right, and the light doesn’t focus exactly on the retina? That’s when we have a refractive error. The image we see is blurry because our eyes aren’t focusing light properly. It’s a bit like using a camera that’s out of focus.
Once again, refractive errors are the reason why people need to wear eyeglasses or contact lens to see clearly. These tools work by refocusing light onto the right spot on the retina, much like adjusting a camera lens brings a photo into perfect focus.
What are the Different Types of Refractive Errors
- Myopia (Short-sightedness, also known as near-sightedness):
Myopia is a condition where you can see near objects clearly, but distant objects appear blurry. This blurriness occurs because the eye’s length is longer than normal, or the cornea is too curved, causing light to focus before it reaches the retina. Myopia often begins in childhood and may gradually worsen as the person grows, stabilizing in early adulthood. Signs of myopia include squinting, eye strain, headaches, and feeling fatigued when driving or playing sports.
- Hyperopia (Far-sightedness): If you have hyperopia, you can see distant objects clearly, but close-up objects are blurry. This happens because the eye is shorter than normal, or the cornea is too flat, causing light to focus behind the retina. Some children have mild hyperopia that corrects itself as they grow and their eyeballs lengthen. However, adults can also develop hyperopia. Struggling to focus on close-up tasks like reading or computer work are common symptoms.
- Astigmatism: Astigmatism causes blurred or distorted vision at all distances, unlike myopia and hyperopia that affect vision at either close or far distances. It happens when the cornea or lens isn’t evenly curved, almost like a football shape instead of a perfect sphere. This irregularity redirects the light to focus on multiple points around the retina rather than directly on it. Astigmatism can accompany myopia or
hyperopia and often causes eye strain and headaches, especially after reading or other prolonged visual tasks.
- Presbyopia: Unlike the other refractive errors, presbyopia is an age-related condition that affects near vision. It occurs when the lens inside the eye becomes less flexible over time, making it harder to focus on close objects. Presbyopia typically starts around the age of 40 and affects everyone, even those who have never had a vision problem before. Early signs include needing to hold reading materials at arm’s length, blurred vision at normal reading distance, and eye fatigue along with headaches when doing close-up work.
Each type of refractive error has unique causes and symptoms, but all result in vision that’s less sharp than it could be. The good news is that all these refractive errors can be effectively corrected with eyeglasses, contact lenses, or refractive surgeries, allowing you to enjoy clear vision once again.
What Causes Refractive Errors?
While the exact causes are unknown, refractive errors are often related to the eye’s shape and size and the cornea’s curve and thickness. Genetics also play a significant role, as refractive errors are often hereditary.
Symptoms of Refractive Errors
Common signs and symptoms associated with refractive errors include:
- Blurred vision, either for near or distant objects
- Double vision
- Glare or halos around lights
- Eye strain or discomfort
- Frequent headaches
- Squinting
- Difficulty with night vision or reading
Diagnosing Refractive Errors
An optometrist or ophthalmologist can diagnose refractive errors during a comprehensive eye examination. They usually perform visual acuity tests using a wall chart and a refraction test to determine the lens power needed to correct the refractive error.
Treatment Options for Refractive Errors
Addressing refractive errors involves modifying the way light enters your eye, allowing images to focus on the retina and deliver a clear vision. There are several effective treatments for refractive errors, each with its advantages, which your eye care professional can discuss with you in detail.
- Eyeglasses: This is the simplest and safest method to correct refractive errors. Eyeglasses work by adding or subtracting focusing power to the eye’s cornea and lens to sharpen the image on the retina. The wide array of available frame designs and lens types allows for personal customization based on your lifestyle, aesthetics, and comfort.
- Contact Lenses: Contact lenses, placed directly on the surface of the eye, can provide a more natural field of view than eyeglasses. They also eliminate the need for frames, thus offering aesthetic appeal. Various types exist, including soft lenses, rigid gas permeable lenses, and hybrid lenses. Each type has its pros and cons, and your eye care provider can help determine the best option for you.
- Orthokeratology (Ortho-K): This non-surgical procedure involves wearing rigid contact lenses that reshape the cornea while you sleep, temporarily correcting mild to moderate amounts of myopia or astigmatism. Once you remove the lenses in the morning, the temporary reshaping allows for clearer vision during the day.
- Refractive Surgery: Surgical procedures aim to eliminate or reduce the need for eyeglasses or contact lenses. Common types include:
- LASIK (Laser-Assisted In Situ Keratomileusis): The surgeon creates a thin flap in the cornea, removes some corneal tissue using an excimer laser, and then repositions the flap. The laser reshapes the cornea, allowing light entering the eye to be properly focused onto the retina for clearer vision.
- PRK (Photorefractive Keratectomy): In PRK, the surgeon removes the cornea’s outer layer and uses an excimer laser to reshape it, correcting the refractive error. PRK does not involve creating a corneal flap, making it a suitable option for people with thinner corneas.
- SMILE (Small Incision Lenticule Extraction): A minimally invasive procedure where a small piece of corneal tissue is removed, changing the cornea’s shape and correcting the refractive error. SMILE has a faster recovery time and a lower risk of complications compared to other procedures.
- Refractive Lens Exchange (RLE): RLE involves removing the eye’s natural lens and replacing it with an artificial one. This procedure is typically used for people with presbyopia or extreme farsightedness.
- Implantable Lenses (Phakic IOLs): For patients with high levels of myopia or hyperopia, or those who aren’t good candidates for corneal reshaping procedures, implantable lenses can be an option. The surgeon inserts these lenses into the eye without removing the natural lens, providing high-quality, high-definition vision.
Each treatment has its risks and benefits, and the best choice depends on several factors, including your refractive error’s type and severity, your lifestyle, your age, and your eye’s overall health. A comprehensive discussion with your eye care provider will ensure that you choose the best treatment for your specific needs.
Frequently Asked Questions (FAQs)
Q: Are refractive errors serious? A: Generally, refractive errors are not dangerous, but if left untreated, they can significantly impact your vision and quality of life. Severe untreated refractive errors in children can lead to amblyopia, or lazy eye.
Q: Can I prevent refractive errors? A: Since refractive errors are typically related to genetics and the natural aging process, they cannot be prevented. However, regular comprehensive eye examinations can ensure early detection and treatment to prevent vision impairment.
Q: Do refractive errors worsen with age? A: Presbyopia, a specific type of refractive error, worsens with age. This condition usually becomes noticeable around the mid-40s and continues to worsen until approximately age 65.
Q: What are the surgical options for correcting refractive errors? A: There are several surgical procedures to correct refractive errors, including LASIK, PRK, and refractive lens exchange. However, the appropriateness of surgery depends on factors such as the type and severity of refractive error, the health of the eye, and the patient’s age and lifestyle.
Q: Can refractive errors be corrected at any age? A: Yes, refractive errors can be corrected at any age. Eyeglasses and contact lenses can be used by people of all age groups. Refractive surgery, however, is usually only recommended for adults whose eyes have stopped growing, typically around age 20.
Q: Is laser refractive surgery safe? A: Laser refractive surgery, such as LASIK, PRK, and SMILE, are generally safe and effective when performed by an experienced surgeon. However, as with any surgical procedure, there are risks involved. Potential complications may include dry eyes, glare, halos around lights, undercorrections, overcorrections, and even loss of vision in rare cases. It’s important to discuss these risks with your surgeon prior to the procedure. Following all pre- and post-surgery instructions can also help minimize these risks. For more information, click on the laser refractive surgery page you are interested in (e.g. LASIK) under the tab ‘Procedures’.
Q: Are contact lenses safer than laser eye surgery? A: Comparing the safety of contact lenses to laser eye surgery isn’t straightforward, as both have potential risks and benefits. While laser eye surgery carries risks associated with surgical procedures, it is a generally safe and permanent solution for vision correction. On the other hand, contact lenses, when used and cared for properly, are also a safe method for vision correction. However, they carry risks of eye infections, particularly if hygiene guidelines are not strictly followed or if they’re worn longer than recommended. The decision between contact lenses and laser surgery should be made in consultation with your eye care professional, considering factors like your lifestyle, age, eye health, and personal comfort.
Q: What are the outcomes like for laser refractive surgery? A: The majority of patients who undergo laser refractive surgery report significant improvement in vision, with many achieving 20/20 vision or better. However, results can vary depending on the type and severity of refractive error, overall eye health, and individual healing patterns. Some patients may still need to use glasses or contact lenses for certain activities following the procedure. It’s also important to note that while laser refractive surgery can effectively treat myopia, hyperopia, and astigmatism, it cannot prevent age-related conditions such as presbyopia or cataracts. You should have a detailed discussion with your surgeon about your expected outcomes before the procedure.
Q: Can a person have more than one type of refractive error? A: Yes, it’s possible to have more than one type of refractive error at the same time. For example, it’s common for someone to have both myopia and astigmatism.
Q: I spend a lot of time looking at computer screens. Can this cause refractive errors? A: While prolonged screen time can lead to eye strain, dry eyes, and discomfort, there is currently no scientific evidence that it causes refractive errors.
Q: What lifestyle changes can help manage refractive errors? A: Good visual habits like regular breaks during prolonged close work, adequate lighting when reading, maintaining a healthy diet rich in vitamins A, C, and E, and protecting your eyes from excessive sunlight with sunglasses can help in managing refractive errors.
Q: Do refractive errors affect only vision or other aspects of health too? A: While primarily affecting vision, untreated refractive errors can lead to other health problems, including headaches, nausea, dizziness, and even learning difficulties in children due to unclear vision.
Q: How often should I get my eyes checked for refractive errors? A: Regular eye check-ups are crucial in the early detection and management of refractive errors. Children should have their first eye examination at 6 months, then at age 3, and again before they start school. Adults should get their eyes checked at least every two years, or more frequently if recommended by their eye doctor.
Q: Are contact lenses better than glasses for refractive errors? A: Both contact lenses and glasses effectively correct refractive errors. The choice between the two often depends on personal preference, comfort, lifestyle, and the type and severity of the refractive error. Some people find that contact lenses offer better peripheral vision and are more suitable for sports, while glasses don’t touch the eyes and require less cleaning.
Q: Can refractive errors lead to blindness? A: Refractive errors themselves cannot lead to blindness. However, significantly impaired vision from untreated refractive errors can limit people’s ability to perform daily tasks effectively.
Q: Does pregnancy affect refractive errors? A: Pregnancy can lead to changes in refractive error due to hormonal shifts causing fluid retention in the eye, but these changes are usually temporary and resolve after childbirth. It’s advisable for pregnant women to postpone any corrective refractive surgeries until well after childbirth.
Conclusion
Refractive errors, while common, are usually easily corrected with glasses, contact lenses, or surgery. Regular eye exams are critical for maintaining good eye health and detecting these errors early. As always, consult with a healthcare professional for personalized diagnosis and treatment options.
Disclaimer: The information on this page is intended for general educational purposes and is not a substitute for professional tailored medical advice. Always consult with your optometrist or ophthalmologist for accurate diagnosis and treatment.