Astigmatism

Disease Description (Causes and Symptoms)

• Definition summary: Astigmatism is a refractive error in which the curvature of the cornea or lens (primarily the cornea) is steeper or flatter in one direction, like a hairline, so that light rays cannot converge at a single point on different meridional planes (one axis and the other axis). As a result, images may appear blurred or doubled.
• Causes and pathophysiology:
  • Main cause: Asymmetric curvature of the cornea (toric cornea). Asymmetry of the lens (lenticular astigmatism) can also be a cause.
  • Genetic predisposition, continuous pressure from the eyelids (such as ptosis), pterygium (skin tissue growing onto the cornea), and changes after corneal trauma or surgery may be associated.
  • Astigmatism is divided into regular astigmatism (when the two principal axes are perpendicular) and irregular astigmatism (when the principal axes are not constant due to an irregular corneal surface).
• Main symptoms:
  • Blurred vision at both distance and near (not only appearing as nearsightedness).
  • Reduced visual acuity; objects may appear doubled or distorted.
  • Eye fatigue, headache, eye pain, or redness.
  • In children, reduced visual development or a risk of amblyopia (in cases of predominantly unilateral astigmatism).

Treatment Methods

• Non-surgical correction:
  • Glasses: Correct the refractive error with cylindrical lenses for astigmatism. This is the most common and safest method.
  • Contact lenses:
    • Toric soft lenses (commonly used for mild to moderate astigmatism).
    • Rigid gas-permeable (RGP) lenses can correct corneal irregularities and improve clarity (advantageous for irregular astigmatism).
• Surgical treatment:
  • Laser refractive surgery (LASIK/PRK/LASEK, etc.): In cases of regular astigmatism, correction may be possible by reshaping the cornea to adjust the axis. Evaluation of indications and risks is necessary.
  • SMILE: Astigmatism correction may be possible in some cases.
  • Toric intraocular lens implantation during cataract surgery: Simultaneously corrects astigmatism in patients with cataracts.
  • If the ocular surface is irregular (such as with pterygium), treat the lesion and then reassess.
• Other management:
  • Children: Early examination and wearing glasses are recommended for visual development; in severe cases, amblyopia treatment (such as patching) may be necessary.
  • Lifestyle management: Take breaks after prolonged near work (such as following the 20-20-20 rule), maintain appropriate lighting, and practice good contact lens hygiene.
• Precautions:
  • Check for changes in prescription through regular vision examinations.
  • Contact lens use carries a risk of infection (keratitis), so follow instructions for use and care.
  • Detailed examinations are necessary before laser surgery (including evaluation of corneal thickness, topography, and dry eye). Rare postoperative complications such as corneal ectasia may occur.

Checklist Before an Outpatient Visit (Including Example Questions)

• Items to prepare:
  • Bring the glasses and contact lenses you currently wear (prescription or lenses).
  • A list of medications you are taking, including eye drops, and a history of previous eye surgery or trauma.
  • Previous vision examination results or corneal topography and other test results, if available.
  • A record of symptom changes: when the changes began, differences between one eye and both eyes, and changes in specific situations (fatigue, lighting), etc.
• Precautions before examination:
  • Contact lens wearers need to stop wearing lenses for a certain period before the examination (from several hours to several days depending on the type of examination); follow the doctor's instructions.
• Examples of simple symptom descriptions that can be presented to the doctor during the outpatient visit:
  • “For the past two months, both near and distant objects have appeared blurry, and my eyes seem more tired in the evening.”
  • “Even after changing my glasses, letters still appear doubled.”
• Information the healthcare professional may ask about during the consultation:
  • When the symptoms began, how they have changed, family history (astigmatism or refractive errors), sleep and work habits, whether you use contact lenses, etc.

General Example Questions to Ask the Doctor

• "How severe is my astigmatism exactly (what is the prescription)?"
• "Which correction method—glasses or contact lenses—is most appropriate for me?"
• "What are the side effects of this medication (eye drops or oral medication)?"
• "Can laser surgery completely eliminate it? What are the advantages, disadvantages, and risks of the surgery?"
• "What is the prognosis? Is my vision likely to worsen in the future?"
• "What lifestyle precautions should I take (contact lens care, work breaks, etc.)?"

Examples of Condition-Specific Questions

• For parents or guardians of pediatric patients: "Is my child's astigmatism at risk of progressing to amblyopia? When should vision correction or amblyopia treatment begin?"
• For those considering surgery: "Please explain whether my corneal topography results are suitable for surgery (LASIK/LASEK/toric IOL), and whether surgery may be restricted due to corneal thickness, dry eye, or other factors."