Astigmatism is a common condition that causes blurred or distorted vision at any distance because the eye processes light incorrectly. This refractive error occurs when the cornea or the lens inside the eye is curved unevenly, resembling a football rather than a perfectly round basketball. This irregular curvature causes light to focus unevenly on the retina, leading to visual distortion. Surgical correction is a widely available and effective option for individuals seeking to permanently reshape the eye’s optics and eliminate reliance on glasses or contact lenses.
Primary Laser Correction Procedures
Laser-Assisted In Situ Keratomileusis, or LASIK, is the most frequently performed procedure, utilizing two different types of lasers. A femtosecond laser first creates a thin, hinged flap on the outermost layer of the cornea. This flap is gently lifted to expose the underlying corneal tissue. Once the flap is moved aside, an excimer laser vaporizes microscopic amounts of tissue, sculpting the corneal bed into a symmetrical shape to neutralize the astigmatism.
The flap is then repositioned, adhering naturally without the need for stitches. This process generally maintains the cornea’s structural integrity and allows for a rapid visual recovery.
Photorefractive Keratectomy, or PRK, achieves the same corneal reshaping without creating a flap. The surgeon first removes the epithelium, the thin, superficial layer of the cornea. The excimer laser is then applied directly to the underlying tissue to correct the refractive error. PRK is often recommended for individuals with corneas too thin for LASIK or those whose professions involve a high risk of eye trauma.
Small Incision Lenticule Extraction, or SMILE, is a newer, minimally invasive, flap-free technique requiring only a single femtosecond laser. This laser creates a small, lens-shaped piece of tissue, known as a lenticule, within the middle layer of the cornea. The surgeon removes the lenticule through a small incision, typically 2 to 4 millimeters wide. This permanently changes the corneal shape, correcting astigmatism while potentially preserving more biomechanical strength compared to LASIK.
Essential Criteria for Surgical Candidacy
A fundamental requirement for candidacy is that the patient must be at least 18 years old, as the eyes need to have reached ocular maturity. The patient’s refractive error prescription must also have remained stable for a minimum of 12 months. Fluctuating vision suggests the eye is still changing, which would compromise the predictability and longevity of the surgical result.
Another determining factor is the thickness of the cornea, which is assessed through corneal topography. Since laser correction removes tissue to reshape the cornea, sufficient tissue must remain to ensure structural stability after the procedure. A detailed map of the cornea is necessary to plan the treatment, as most corneas are around 540 to 550 microns thick.
Patients must demonstrate good overall eye health. Conditions such as active infection, uncontrolled diabetes, certain autoimmune disorders, or advanced dry eye must be addressed or resolved before surgery. Keratoconus, a progressive thinning and outward bulging of the cornea, is an absolute contraindication for laser vision correction. Women who are pregnant or breastfeeding are advised to delay the procedure because hormonal fluctuations can temporarily alter a prescription.
Recovery Timeline and Post-Operative Care
The recovery experience varies depending on the specific procedure, but immediate post-operative care shares similar principles across all laser corrections. Following LASIK or SMILE, most patients notice a dramatic improvement in vision within the first 24 to 48 hours. The eyes may feel gritty or mildly uncomfortable, and patients are instructed to rest and wear protective shields, especially while sleeping. It is important to avoid reading or screen use for the first day to minimize eye strain and facilitate initial healing.
The initial recovery for PRK is longer because the epithelial layer must regenerate, which often takes three to seven days. During this time, a bandage contact lens is worn for protection, and patients may experience moderate discomfort and more pronounced light sensitivity. Regardless of the technique, prescription eye drops, including antibiotics and anti-inflammatory medications, must be applied meticulously to prevent infection and control inflammation.
For the first one to two weeks, patients must follow several restrictions to ensure the best outcome and prevent complications. Activities that increase the risk of infection or trauma, such as swimming, using hot tubs, or applying eye makeup, are temporarily prohibited. While light exercise can be resumed quickly, strenuous activities and contact sports are restricted for at least a few weeks. Common temporary side effects include glare, halos around lights, and dry eyes, which are managed with lubricating drops. Full visual stabilization, where the final, sharpest vision is achieved, generally takes between one and three months.