What are the treatment options for correcting astigmatism?

Astigmatism Correction: Treatment Options

For astigmatism correction, the treatment approach depends on severity: low-to-moderate astigmatism (less than 3.00 D) is best corrected with eyeglasses, soft toric contact lenses, or rigid gas-permeable lenses, while high astigmatism (3.00 D or more) requires rigid gas-permeable lenses, hybrid lenses, or surgical intervention with toric intraocular lenses during cataract surgery. 1, 2

Eyeglass Correction

Full cylindrical correction may not be necessary or tolerated initially, particularly in adults with previously uncorrected or partially corrected astigmatism. 1, 2

• Adults often cannot accept full cylindrical correction in their first pair of eyeglasses, and substantial changes in axis or power are poorly tolerated. 1
• Gradual correction is better tolerated than immediate full correction. 2
• This conservative approach minimizes adaptation difficulties while still improving visual function. 1

Contact Lens Options

Low-to-Moderate Astigmatism (Less Than 3.00 D)

Soft toric contact lenses or rigid gas-permeable lenses are the primary options for correcting low-to-moderate astigmatism. 1, 2

• Soft toric lenses provide quick adaptation and comfort but may have variable visual acuity due to lens rotation. 3
• Rigid gas-permeable lenses offer clear vision and stable astigmatism correction, making them superior for consistent optical performance. 3
• Daily disposable lenses are the safest option, causing less ocular surface damage and lower rates of infectious or inflammatory complications compared to reusable lenses. 1

High Astigmatism (3.00 D or More)

High astigmatic errors require rigid gas-permeable lenses, hybrid lenses, or custom-designed soft toric lenses. 1, 2

• Bitoric or back-surface toric contact lens designs minimize corneal bearing and improve centration for greater amounts of corneal astigmatism. 1, 2
• Custom-designed soft toric lenses provide good centration, flexible wear schedules, and improved comfort. 1, 2
• Rigid gas-permeable scleral lenses (diameter greater than 17 mm) are effective for high and/or irregular astigmatism, particularly when combined with anisometropia. 1, 2
• The piggyback modality (rigid gas-permeable lens worn over a soft lens) may be useful in select circumstances. 1

Surgical Correction

Cataract Surgery with Astigmatism Management

Toric intraocular lens implantation is the current standard of care for treating astigmatism during cataract surgery, as more than 40% of cataract patients have 1.00 D or more of astigmatism. 4

• Toric IOLs reliably reduce astigmatism and improve uncorrected vision, with 97% of eyes achieving residual refractive cylinder of 1.00 D or less. 5
• For low astigmatism (1.00-2.00 D), clear corneal incision on the steepest meridian is effective and requires no extra skills or tools. 6
• For moderate astigmatism (2.00-3.00 D), opposed clear corneal incisions provide better correction. 6
• For high astigmatism (greater than 3.00 D), toric IOL implantation is superior with proper preoperative planning. 6

Refractive Surgery

Keratorefractive lenticule extraction (KLEx) can correct astigmatism, though nomogram adjustments are essential for optimal outcomes. 1

• Approximately 13% undercorrection occurs in low-to-moderate astigmatism (less than 2.00 D), with 16% undercorrection in high astigmatism (greater than 2.00 D). 1
• Surgeons should increase nomogram values by 10% for target cylinder treatment, especially with preoperative astigmatism greater than 0.75 D. 1

Critical Considerations for Irregular Astigmatism

Irregular astigmatism (seen in keratoconus, corneal scarring, and post-surgical corneas) cannot be fully corrected with spherocylindrical lenses and requires rigid gas-permeable or scleral lenses. 1, 2

• Higher-order aberrations like coma, spherical aberration, and trefoil cannot be corrected by standard eyeglasses. 1
• Rigid gas-permeable lenses are the lenses of choice for irregular and high astigmatism due to clear vision and stable correction. 3

Common Pitfalls to Avoid

• Avoid overcorrecting astigmatism in first-time eyeglass wearers, as this leads to poor tolerance and non-compliance. 1, 2
• Do not prescribe extended wear contact lenses for patients at risk of complications; daily disposable lenses are safer. 1
• Ensure proper keratometry or corneal topography before contact lens fitting to assess relative contributions of cornea and natural lens to astigmatism. 1
• Verify adequate contact lens movement to maintain corneal integrity and comfortable wear. 1