Eye surgery is highly effective at correcting astigmatism, a common refractive error. Astigmatism occurs when the eye’s front surface (the cornea) or the internal lens has an imperfection in its curvature. This causes light to focus unevenly on the retina, resulting in blurred or distorted vision. Surgical correction primarily involves reshaping the cornea to create a more symmetrical surface, allowing light to focus sharply at a single point.
Primary Surgical Procedures for Correction
The most common surgical treatments for astigmatism are laser-based procedures that precisely modify the corneal tissue. These procedures use advanced lasers to vaporize microscopic amounts of tissue, which effectively smooths the irregular curvature. The three main techniques are Laser-Assisted In Situ Keratomileusis (LASIK), Photorefractive Keratectomy (PRK), and Small Incision Lenticule Extraction (SMILE).
LASIK is the most frequently performed procedure, beginning with the creation of a thin, hinged flap on the cornea’s outer layer using either a microkeratome blade or a femtosecond laser. The surgeon lifts this flap, and an excimer laser is used to reshape the underlying corneal tissue. Once reshaping is complete, the flap is carefully repositioned. This method is popular because it allows for a rapid visual recovery.
Photorefractive Keratectomy (PRK) is a surface ablation technique often chosen for patients with thinner corneas. Instead of creating a flap, the surgeon removes the thin outer layer of the cornea, known as the epithelium. The excimer laser then reshapes the underlying corneal tissue. A protective bandage contact lens is placed over the treated area, and the epithelial layer grows back over the next three to five days.
The newest technique is SMILE, which offers a minimally invasive, flap-free alternative. A femtosecond laser creates a small, lens-shaped piece of tissue, called a lenticule, inside the intact cornea. The surgeon removes this lenticule through a small incision, altering the corneal shape to correct the astigmatism. Avoiding a large flap helps maintain corneal structural integrity and may reduce the risk of post-operative dry eye.
Determining Candidacy for Astigmatism Surgery
Not every person with astigmatism is an ideal candidate for laser vision correction; a thorough pre-operative evaluation is required for a safe outcome. Patients must be at least 18 years old, though many surgeons prefer to wait until the mid-twenties. This ensures the prescription has stabilized, typically showing no change greater than 0.5 diopters for 12 to 24 months. Operating on an unstable prescription risks a quickly regressing outcome.
Corneal thickness is a factor, as laser procedures remove tissue to achieve the new shape. Safe surgery requires a minimum residual stromal bed of 250 to 300 microns after the laser application. Patients with corneas thinner than 500 microns may be better suited for PRK, which does not require a flap, rather than LASIK or SMILE.
Certain underlying health conditions can disqualify a patient from laser surgery. Absolute contraindications include keratoconus, an eye disease that causes progressive corneal thinning and bulging. Other conditions, such as uncontrolled diabetes, active autoimmune disorders, and severe dry eye syndrome, can interfere with the healing process. The degree of astigmatism treatable by laser is generally limited to about six diopters, with higher corrections sometimes requiring alternative lens-based procedures.
The Surgical Experience and Post-Operative Care
The actual procedure often takes less than 15 minutes to treat both eyes, though patients should plan to be at the clinic for about two hours. Numbing eye drops are administered to ensure the process is painless, and a mild sedative may be offered. A lid speculum is used to hold the eyelids open during the laser application. Since vision will be blurry immediately afterward, arranging for a reliable driver home is mandatory.
Immediate post-operative care involves resting at home, keeping the eyes closed for several hours to aid the initial healing phase. Protective eye shields must be worn for the first night and while sleeping for the first week to prevent accidental eye rubbing. The surgeon will prescribe medicated eye drops, typically an antibiotic and an anti-inflammatory, to be used multiple times a day for about a week.
The recovery timeline varies significantly between procedures, with LASIK and SMILE offering the quickest visual recovery. Many patients with these procedures are able to drive and return to non-strenuous, desk-based work within 24 to 48 hours. PRK has a longer surface healing time, requiring three to five days for the epithelium to regenerate, and vision takes longer to stabilize. All patients must avoid getting water or soap directly in their eyes for at least a week and are advised to hold off on swimming and contact sports for up to a month.
Potential Outcomes and Managing Expectations
Astigmatism correction surgery is associated with positive outcomes, with most patients achieving improved vision. Clinical data show that over 99% of patients achieve 20/40 vision or better, which is the legal driving standard in most places, and approximately 90% achieve 20/20 vision or better. Final visual acuity typically stabilizes over three to six months as the cornea fully heals.
Patients should be aware of potential temporary side effects that are part of the normal healing process. The most common of these is dry eye, which can last for several months and is managed with frequent application of preservative-free artificial tears. Temporary visual disturbances, such as glare, halos, or starbursts around lights, especially at night, may also occur but generally diminish as the eye recovers.
In a small percentage of cases, typically between one and five percent, the initial correction may result in a slight under- or overcorrection, leaving a residual refractive error. If vision does not settle as expected after the full healing period, an enhancement procedure, or “touch-up,” may be performed to fine-tune the result. For patients with extremely high astigmatism or other contraindications for laser surgery, lens-based procedures like Implantable Collamer Lenses (ICL) or Refractive Lens Exchange (RLE) may be recommended as an alternative to achieve the desired vision correction.