Astigmatism is one of the most common refractive errors we see in İzmir and across Türkiye. A significant portion of patients who visit our Kemalpaşa store have a cylindrical value (CYL) on their prescription. International refractive-error studies report astigmatism in roughly 30-40% of the global population. That makes it far too widespread to overlook.
What Is Astigmatism? How Corneal and Lens Curvature Cause Vision Problems
In a healthy eye, the cornea is shaped like a basketball - uniformly curved in every direction. In astigmatism, the cornea or the lens behind it takes on a shape closer to a football. Flatter along one axis, steeper along the other. Because of this unevenness, light entering the eye focuses on more than one point on the retina rather than a single spot, and the image appears blurry or distorted.
The key difference from myopia or hyperopia is this. Myopia primarily affects distance vision, hyperopia primarily affects near vision. Astigmatism, however, can disrupt vision at both near and far distances. For more on the comparison, see our myopia guide.
Astigmatism falls into two main categories. Regular and irregular. In regular astigmatism, the corneal curvature follows a symmetric pattern. It can be corrected with eyeglasses or toric lenses. In irregular astigmatism, the corneal surface has taken on an inconsistent shape. This pattern is seen in conditions such as keratoconus.
Symptoms of Astigmatism: Don't Overlook the Signs
The clearest sign of astigmatism is blurry or distorted vision - at both near and far distances. Beyond that, the following symptoms often accompany it.
Headaches after prolonged reading or screen use
Eye strain and a burning sensation
Halos and glare around light sources at night or in low-light driving
Constant squinting to see clearly
Not all of these symptoms need to appear at once. Sometimes the only sign is chronic headache. People mistake it for migraine or fatigue and live with it unnoticed for years.
Why Astigmatism Symptoms Often Go Unnoticed in Children
Children assume what they see is "normal" and rarely complain. For them, blurry vision is simply how things look. That's why parents and teachers usually spot the symptoms first.
The signals to watch for include unexplained drops in school performance, trouble seeing the board, holding books very close to the face, and frequent headache complaints. Studies conducted at university clinics in Türkiye report astigmatism prevalence among school-age children in the 20-35% range. That number makes regular eye check-ups all the more important.
We recommend regular eye exams starting from preschool age. For more on the eyewear process for children, see our guide to kids' glasses.
Astigmatism Diopters: What Do the CYL and Axis Numbers Mean?
If you see CYL and AXIS values on your prescription, you have astigmatism. The two values are read together.
CYL (cylinder) shows the strength of the astigmatism in diopters. The general grading is as follows.
CYL < 1.00 D - low astigmatism
CYL 1.00-2.00 D - moderate astigmatism
CYL > 2.00 D - high astigmatism
AXIS is a value between 0° and 180° that indicates the orientation of the flattest meridian of the cornea. It determines the direction in which the lens applies its correction. Even a few degrees off can noticeably affect image quality - which is why the axis value must be applied with high precision during lens mounting.
If your prescription has both a spherical (SPH) and a cylindrical (CYL) value, you may have either myopic astigmatism or hyperopic astigmatism. These combinations require both refractive errors to be addressed together during correction.
Regular and Irregular Astigmatism: The Keratoconus Connection
In regular astigmatism, the corneal curvature follows a symmetric pattern. Full correction is achievable with standard cylindrical eyeglass lenses or toric contact lenses.
In irregular astigmatism, the corneal surface has taken on an inconsistent and asymmetric shape. Keratoconus is the most well-known cause of this pattern. The cornea progressively thins and takes on a conical shape. In this case, standard glasses or toric lenses are not enough. Rigid gas-permeable (RGP) or scleral lenses may be required. The distinction between regular and irregular astigmatism is made with corneal topography.
The prevalence of keratoconus in the general population ranges roughly between 1 in 2,000 and 1 in 375. The rate varies based on the screening method and the population studied. The Turkish Ophthalmological Association emphasizes the importance of keratoconus screening in patients with astigmatism.
Important note. If irregular astigmatism is suspected, if you are experiencing sudden changes in vision, or if your current glasses don't provide sufficient correction, see an ophthalmologist (eye doctor). At İlhan Optik we perform refraction measurements, produce cylindrical eyeglass lenses, and fit toric contact lenses. However, disease diagnosis and medical assessment fall within the eye doctor's scope.
How Astigmatism Is Corrected: Glasses, Toric Lenses, and Surgical Options
There are three main ways to correct astigmatism. Each differs in scope and in who is responsible for it.
1. Cylindrical eyeglass lenses
The most common and accessible option. Custom-made based on CYL and AXIS values, these lenses correct the image by applying different power in different meridians. This falls within the optician's scope.
2. Toric contact lenses
Standard contact lenses cannot correct astigmatism. Specially designed toric lenses are required. Each lens needs a curve and axis alignment specific to the eye, and the fitting is performed by an optician. An estimated 30% of contact-lens wearers globally need astigmatism correction. To learn more about toric contact lens fitting, please get in touch.
3. Laser surgery (LASIK, PRK, SMILE)
These are surgical options that permanently reshape the cornea. The decision and procedure fall entirely within the eye doctor's (surgeon's) authority. The Turkish Ophthalmological Association considers preoperative topographic evaluation mandatory for LASIK and recommends keratoconus screening. We provide information on this topic. We do not refer patients for surgery.
Choosing Astigmatism Glasses: Why Cylindrical Lenses Require Custom Manufacturing
Unlike standard spherical lenses, cylindrical lenses carry different optical power in different meridians. This structure makes it essential that the lens be mounted at exactly the correct axis. Even a few degrees of deviation can noticeably degrade image quality.
For that reason, lens quality and mounting precision are critical. We source our lenses from authorized suppliers such as Zeiss, Hoya, and Essilor. These brands deliver consistent optical performance in cylindrical production.
Frame selection also matters. With high astigmatism, large and thin frames can increase the edge thickness of the lens. The right frame choice makes a difference both visually and aesthetically. If you like your current frame, you can also have only the lens replaced through our cylindrical lens replacement option.
What to Do Next If You Suspect Astigmatism in İzmir or Kemalpaşa
We want to keep our role as opticians clear. At our store we perform refraction measurement (eye test), manufacture cylindrical eyeglass lenses based on existing prescriptions, and fit toric contact lenses and provide usage training.
Diagnosing astigmatism, identifying disease, and deciding on surgical intervention fall within the ophthalmologist's scope. In the following cases, please see an eye doctor.
If you are being evaluated for astigmatism for the first time
If you have high or irregular astigmatism
If you experience sudden or rapid changes in vision
If keratoconus is suspected
If you already have a prescription and would like glasses or toric lenses made, we look forward to seeing you at İlhan Optik in Kemalpaşa. We're roughly 25 minutes from Bornova and 35 minutes from Buca in İzmir. You can stop by our store on Kirazlı Caddesi in the Mehmet Akif Ersoy neighborhood, or send your questions via WhatsApp.
If you're experiencing blurry vision, headaches, or eye strain, you can start by booking a refraction measurement appointment.
