Astigmatism: Causes, Symptoms, Diagnosis, and Treatment

When the cornea, the front surface of the eye, or the lens within the eye has uneven curves, astigmatism results. The surface is formed like an egg rather than having a single curve like a spherical ball. Vision becomes hazy as a result of all distances.

It is common for astigmatism to be present from birth and to coexist with either near- or farsightedness. Frequently, it is not severe enough to call for correction. If so, the only available treatments are surgery or corrective lenses.

Astigmatism: Causes

Two curved-surfaced structures in the eye bend (refract) light onto the retina to create the pictures, which are −

• The tear film and cornea, the transparent front surface of the eye

• The lens, a transparent component of the eye that modifies shape to aid in the eye's ability to concentrate on close objects

Each of these components has a round curvature, similar to the surface of a smooth ball, in a properly formed eye. An image that is highly focused and immediately on the retina at the back of the eye is created by a cornea or lens with such a curvature, which bends (refracts) all incoming light equally.

A Distortion of Focus

Light rays aren't bent in the same way if either the cornea or the lens has an egg shape with two misaligned curves, which results in the formation of two separate pictures. Vision is blurred as a result of the overlap or combination of these two pictures. A specific kind of refractive error is astigmatism.

When the cornea or lens curves more sharply in one direction than another, astigmatism results. If your cornea has uneven curvature, you have corneal astigmatism. If the curves on your lens are out of alignment, you have lenticular astigmatism.

Vision blurring may result from any form of astigmatism. Vision fuzziness may be more prevalent in one direction: either horizontally, vertically, or diagonally.

Astigmatism can appear after an eye injury, illness, or surgery, or it can appear from birth. Reading in dim light, watching TV too close, or squinting do not create astigmatism or make it worse.

Additional Refraction Errors

Other refractive defects that may coexist with astigmatism include −

• Nearsightedness (myopia). This happens when the eye is longer than usual or the cornea is too curled. Light is directed in front of the retina rather than squarely on the retina, blurring distant objects.

• Farsightedness (hyperopia). This happens when the eye is shorter than usual or the cornea is not curled enough. Nearsightedness has the opposite impact. Because light never focuses on the rear of the eye while the eye is relaxed, surrounding things seem fuzzy.

Astigmatism: Symptoms

Astigmatism symptoms and signs might include −

• Distorted or blurry vision

• Tired or uncomfortable eyes

• Headaches

• Problems with night vision

• Squinting

When to Visit a Doctor

If your eye problems interfere with your ability to carry out daily chores or reduce your pleasure of hobbies, see an eye doctor. The presence and severity of astigmatism can be determined by an eye doctor. Then, he or she can inform you of your possibilities for vision correction.

Children and Teenagers

Children should be screened for eye diseases and have their vision checked by a pediatrician, ophthalmologist, optometrist, or another professional screener at the following ages and intervals since they might not be aware that their vision is impaired.

• In the early weeks after birth

• Until they are of school age, during well-child visits.

• Every one to two years during the school year, during well-child checks, eye doctor appointments, or via screenings at schools or in the community.

Astigmatism: Risk Factors

The major risk factors include −

• Hereditary factors, such as a history of astigmatism, eye conditions, or conditions like keratoconus

• Eye surgery – Certain procedures involving the eyes, such as cataract removal

• A background of corneal thinning or scarring

• Extreme nearsightedness or farsightedness in the past

Astigmatism: Diagnosis

Astigmatism can be identified by ophthalmologists during a thorough eye examination. Testing could involve −

• Eye diagram. On an eye chart, you will be required to read the letters. This evaluates your ability to see well at different distances, or visual acuity.

• Phoropter. You inform your doctor which letter you can see better by peering through a huge, binocular-like gadget. Your doctor formulates a prescription for you that will give you the best eyesight possible based on the information you submit.

• Autorefractor. Additionally, this tool aids in determining your astigmatism or other refractive defects. It operates by projecting light into the eye and seeing how the light changes as it reflects off the retina.

• The corneal curvature may be measured with a keratometer. In order to detect flaws and deformities on the corneal surface, your eye doctor may also do a corneal topography scan.

Astigmatism: Treatment

To increase eye comfort and vision clarity, astigmatism is treated. Corrective lenses or refractive surgery are available as treatments.

Adaptive Eyewear

Astigmatism is treated by wearing corrective lenses, which balance out the irregular curvatures of your cornea or lens.

Corrective eyewear varieties include the following options −

Eyeglasses

Lenses for eyeglasses are created to assist account for the irregular shape of the eye. The lenses correctly bend the light as it enters the eye. Other refractive problems, such as nearsightedness or farsightedness, can also be corrected using eyeglasses.

Lens Contacts

Contact lenses may usually correct astigmatism, much as eyeglasses. They come in a wide range of sorts and designs.

Additionally, contact lenses are employed in a process known as orthokeratology. In orthokeratology, stiff lenses are worn at night while you sleep until your eyes' curvature is uniform. In order to preserve the new form, the lenses are then worn less often. The eye recovers to its original shape and refractive error if therapy is stopped.

The likelihood of developing an eye infection rises with prolonged contact lens use. Inquire with your eye doctor about the benefits, drawbacks, dangers, and possible best options for you.

Surgery for Refractive Error

Refractive surgery enhances eyesight and lessens dependence on contact lenses or spectacles. The cornea's curves are modified by an eye surgeon using a laser beam to rectify the refractive defect. Doctors will examine you and assess whether you are a candidate for refractive surgery before the procedure.

Refractive surgery for astigmatism comes in a variety of forms.

• Keratomileusis in situ with laser assistance (LASIK). An eye surgeon creates a tiny, hinged flap in the cornea using this technique. He or she shapes the cornea using an excimer laser before repositioning the flap.

• A subepithelial keratectomy with laser assistance (LASEK). The thin protective layer (epithelium) of the cornea is loosened by the surgeon using a specific alcohol rather than by making a flap in the cornea.

• Extracting lenticules with a little incision (SMILE). By creating a lens-shaped piece of tissue (lenticule) beneath the cornea's surface with the aid of a laser, this more recent form of refractive surgery reshapes the cornea. A very little incision is made to remove the lenticule. The SMILE technique is currently only authorized to cure moderate nearsightedness.

Astigmatism: Prevention

There isn't a way to stop it. Astigmatism can be acquired as a kid or young adult for many people, while some people are born with it. Following an eye injury or eye surgery, astigmatism can also occur in certain people.

Conclusion

One of the most often treated refractive defects in clinical ophthalmology practice is astigmatism. The necessity of astigmatism's reliable clinical care is underscored by the condition's severe functional and visual effects.