What are the treatment options for a patient with astigmatism?

Treatment for Astigmatism

Eyeglasses are the first-line treatment for astigmatism, followed by contact lenses for those who cannot tolerate spectacles, and refractive surgery for appropriate candidates seeking spectacle independence. 1

Eyeglass Correction (First-Line Treatment)

The American Academy of Ophthalmology recommends eyeglasses as first-line treatment before contact lenses or refractive surgery for both with-the-rule and against-the-rule astigmatism. 1

• Full cylindrical correction with eyeglasses effectively treats astigmatism, though adults with previously uncorrected astigmatism may require gradual correction to improve tolerance 1
• Full cylindrical correction may not be needed initially, particularly for adults with regular astigmatism, as substantial changes in axis or power are poorly tolerated 1, 2
• High-index lenses reduce thickness and weight for higher refractive errors, improving comfort and cosmetic appearance 1

Common Pitfall

Adults with astigmatism may not accept full cylindrical correction in their first pair of eyeglasses; gradual correction is better tolerated 2

Contact Lens Correction (Second-Line)

Contact lenses are appropriate when patients cannot tolerate eyeglasses or prefer them for lifestyle reasons. The selection depends on the degree of astigmatism:

Low to Moderate Astigmatism (< 3.00 D)

• Soft toric contact lenses or rigid gas-permeable (RGP) contact lenses effectively correct low to moderate astigmatism 3, 1, 2
• Custom-designed soft toric lenses provide good centration, flexible wear schedules, and improved comfort 3, 1
• Daily disposable lenses have emerged as the safest soft lens option, with the lowest likelihood of infectious or inflammatory complications 3

High Astigmatism (≥ 3.00 D)

• Rigid gas-permeable and hybrid contact lenses are highly effective for high astigmatic errors 3, 1, 2
• Bitoric or back-surface toric designs minimize corneal bearing and improve centration for greater amounts of corneal astigmatism 3, 1, 2
• RGP scleral lenses (diameter > 17 mm) are excellent options for high and/or irregular astigmatism, particularly with anisometropia 3, 1, 2

Safety Considerations

• Rigid gas-permeable corneal lenses have the lowest rate of adverse events of any lens type 3
• Daily disposable lenses worn on a daily-wear basis remain the safest soft lens regimen 3
• Extended (overnight) wear increases the likelihood of infection regardless of lens type 3
• Hydrogen peroxide disinfection has the lowest rate of adverse events compared with any other disinfection system 3

Refractive Surgery (For Appropriate Candidates)

Surgical correction is appropriate for patients seeking spectacle independence who meet candidacy criteria:

Laser Corneal Ablation

• Laser corneal ablation is highly effective for correcting low-to-moderate levels of astigmatism and may be the best option for younger patients 4
• Photorefractive Keratectomy (PRK) involves removing the central corneal epithelium and using excimer laser to ablate Bowman layer and superficial corneal stroma 1
• LASIK procedures include PRK variants (LASEK, epi-LASIK), LASIK, SMILE, and astigmatic keratotomy (AK) 1
• Mitomycin-C (0.02% for approximately 15 seconds) is often used off-label to reduce corneal subepithelial haze, particularly with high corrections 1

Critical Technical Considerations

• Axis alignment and cyclotorsion compensation are critical for astigmatism correction, as misalignment significantly reduces treatment effectiveness 1, 2
• Reference marks must be placed on the operative eye while the patient is seated upright before laser procedures to compensate for ocular cyclotorsion 1
• Iris registration or tracking systems help maximize accuracy of the astigmatic ablation axis 1
• Larger optical zones result in less undercorrection and fewer higher-order aberrations, particularly in high myopia, but require sufficient corneal thickness 1
• Wavefront-guided or wavefront-optimized techniques maintain a more prolate corneal shape, reducing induced spherical aberration 1

Keratorefractive Lenticule Extraction (KLEx)

• KLEx corrects astigmatism ranging from 0.25 D to 5.00 D, with cyclotorsion compensation significantly improving outcomes and lower residual astigmatism 1

Toric Intraocular Lenses (For Cataract Patients)

• Toric IOLs may be used to correct preoperative regular keratometric astigmatism in presbyopic patients with astigmatism 5
• Toric IOLs provide lower residual astigmatism than nontoric IOLs even when corneal relaxing incisions are used 5
• Both peripheral corneal-relaxing incisions and cataract extraction with toric intraocular lenses have proven effective for eyes with astigmatism and cataracts 4

Absolute Contraindications to Refractive Surgery

• Insufficient corneal thickness for proposed ablation depth 1
• A minimum of 250 μm residual stromal bed thickness has been suggested for LASIK procedures, though no absolute value guarantees that ectasia will not occur 3
• Percentage of tissue altered (PTA) ≥ 40% has been associated with higher ectasia risk in the context of normal preoperative topography 3

Relative Contraindications

• Significant irregular astigmatism 1
• Abnormal topography is the most significant risk factor for postoperative ectasia 3

Special Considerations for Irregular Astigmatism

Irregular astigmatism (seen in keratoconus, corneal scarring, and post-surgical corneas) cannot be fully corrected with spherocylindrical lenses and requires specialty contact lenses or surgical intervention. 2

• Rigid gas-permeable scleral lenses are particularly effective for irregular astigmatism 3, 1
• The piggyback modality, in which a rigid gas-permeable lens is worn on top of a soft lens, may have utility in some circumstances 3

Orthokeratology (Reversible Non-Surgical Option)

• Rigid gas-permeable contact lenses can be prescribed as a nonsurgical and reversible method for mild to moderate myopia with less than 1.50 D of corneal astigmatism 3
• Patients wear reverse-geometry rigid gas-permeable contact lenses only during sleep to transiently induce central corneal flattening 3
• FDA approval has been granted for temporary reduction of up to 6.00 D of myopia in eyes with up to 1.75 D of astigmatism 3
• Orthokeratology is associated with an increased risk of microbial keratitis similar to any overnight wear modality 3

Critical Pitfalls to Avoid

• Attempting full cylindrical correction immediately in adults with previously uncorrected astigmatism leads to poor tolerance 1, 2
• Failing to compensate for cyclotorsion during refractive surgery results in axis misalignment and reduced astigmatic correction 1, 2
• When astigmatism determined by subjective refraction differs significantly from corneal topography, lenticular astigmatism is a possible cause, and keratorefractive surgery may not be appropriate 3
• Contact lens-induced corneal warpage requires discontinuation: spherical soft lenses for at least 3 days to 2 weeks, toric soft lenses and rigid lenses for longer periods 3