Astigmatism is a typical vision condition that causes blurred vision. It occurs when the cornea is irregularly shaped or sometimes because of the arch of the lens inside the eye.
Most individuals have some level of astigmatism. Slight astigmatism usually doesn’t influence vision or require treatment, although astigmatism may develop after an eye injury or eye surgery.
Like nearsightedness and farsightedness, astigmatism is a refractive error, which means it is not an eye disease or eye medical issue; it’s simply an issue with how the eye focuses light.
In an eye with astigmatism, light fails to go to a single focus on the retina to create clear vision. Instead, various focus points happen, either before the retina or behind it (or both).
Astigmatism causes vision to be blurred or distorted to some degree at all distances. Symptoms of uncorrected astigmatism are eye strain and headaches, usually due to excessive squinting.
One or both main meridians of the eye are nearsighted.
One or both main meridians are farsighted.
Blended (Dual) Astigmatism
One prinicipal meridian is nearsighted, and the other is farsighted.
Astigmatism also is classified as regular or irregular. In regular astigmatism, the main meridians are 90 degrees separated (opposite to each other). In irregular astigmatism, the meridians are not opposite. Most astigmatism is regular corneal astigmatism, which gives the front surface of the eye a football shape.
Irregular astigmatism can result from an eye injury that has caused scarring on the cornea, from specific types of eye surgery or from keratoconus, a disease that causes a slow thinning of the cornea.
When you read letters on a distance chart, you are measuring your visual acuity. Visual sharpness is given as a division (for instance, 20/40). The top number is the standardized testing distance (20 feet) and the base number is the smallest letter size read. A person with 20/40 visual acuity would need to get within 20 feet to see a letter that should be seen unmistakably at 40 feet. Ordinary distance visual acuity is 20/20.
A keratometer is an instrument used to measure the bend of the cornea. By focusing a ray of light on the cornea and measuring its appearance, it is possible to determine the correct shape of that zone of the cornea’s surface. This measurement is especially important in deciding the best possible fit for contact lenses.
Using an instrument called a phoropter, your optometrist places a series of lenses before your eyes and measures how they focus light. This is performed using a handheld lighted instrument called a retinoscope or a computerized instrument that evaluates the focusing force of the eye. Based on your responses, the power is then refined to decide the lenses that permit the clearest vision. Despite enhanced innovation, objective information remains indispensable in deciding vision needs.
With the data from these tests, your RI optometrist can figure out whether you have astigmatism. Your optometrist will use these findings, consolidated with those of different tests performed, to decide the prescription to give you clear vision.
People with astigmatism usually choose eyeglasses to enhance their vision. The eyeglasses contain a prescription that compensates for the astigmatism. This provides extra power in specific parts of the lens. By and large, a single-vision lens is prescribed to give clear vision at all distances. In any case, patients over age 40 who have presbyopia may require a bifocal or progressive lens.
Some individuals will have better vision with contact lenses as opposed to glasses. Contact lenses may give clearer vision and a more extensive field of view. In any case, since contact lenses are worn specifically on the eyes, they require regular cleaning and care to safeguard eye health.
Spherical soft lenses may not be powerful in addressing astigmatism. Be that as it may, special toric soft contact lenses can adjust for some types of astigmatism. Because rigid gas-permeable contact lenses maintain their regular shape while on the cornea, they can compensate for the cornea’s irregular shape and enhance vision for individuals with astigmatism.
Orthokeratology involves the fitting of a series of inflexible contact lenses to reshape the cornea. The patient wears contact lenses for restricted periods, such as overnight, and then removes them. Individuals with direct astigmatism might have the capacity to achieve clear vision without lenses for most of their daily activities. Orthokeratology does not enhance vision in the long-term. In the event the patient stops wearing the retainer lenses, their vision may return to its original state.
Astigmatism can also be remedied by reshaping the cornea through LASIK (laser in situ keratomileusis) or PRK (photorefractive keratectomy). PRK removes tissue from the superficial and inward layers of the cornea. LASIK removes tissue just from the internal layer of the cornea.
In the event that you have astigmatism, you have an extensive variety of options to adjust your vision issue. In consultation with your RI optometrist, you can select the treatment that best meets your visual and lifestyle needs.
Astigmatism regularly occurs at birth, so it is vital to schedule an eye exam for your child to correct vision problems prior to entering school.
Studies and Stats
In a study of 2,523 American children ages 5 to 17, more than 28 percent had astigmatism of 1.0 diopter (D) or more.
An irregularly shaped cornea or lens prevents light from focusing correctly on the retina, the light-sensitive surface at the back of the eye. As a result, vision becomes blurred at any distance. This can create eye discomfort and headaches.
Astigmatism sometimes occurs with other vision conditions like (nearsightedness) and hyperopia (farsightedness). These vision conditions are refractive errors because they influence how the eyes bend or “refract” light.
The shape of the cornea and lens bends the light entering the eye to focus it precisely on the macula at the back of the eye. In astigmatism, the surface of the cornea or lens has a somewhat different shape.
The surface of the cornea is shaped more like a football instead of round like a basketball, the eye can’t focus light rays to a single point. Vision becomes out of focus at any distance.