What are the current management options for irregular astigmatism?

Management Options for Irregular Astigmatism

The primary management option for irregular astigmatism is rigid gas-permeable contact lenses, which provide superior visual outcomes by masking corneal irregularities and creating a regular anterior refractive surface. 1

Contact Lens Options

Rigid Gas-Permeable (RGP) Contact Lenses

• First-line option for most cases of irregular astigmatism
• Advantages:
  • Mask corneal irregularities by creating a regular anterior refractive surface
  • Provide superior visual outcomes compared to spectacles
  • In the DUSKS study, 93% of patients achieved BCVA of 20/30 or better with RGP lenses 1
• Considerations:
  • May cause discomfort (71% of wearers report some discomfort, 18% report severe discomfort) 1
  • Require proper fitting to ensure adequate movement and corneal integrity

Scleral Lenses

• Particularly effective for severe irregular astigmatism
• Advantages:
  • Do not contact the cornea
  • Not designed to rely on movement for physiologic tolerance
  • Excellent option for high and/or irregular astigmatism, especially with anisometropia 1
  • SPOT scleral lenses have shown significant improvement in visual acuity (average increase of 5 lines) with excellent comfort and satisfaction ratings 2
• Considerations:
  • Require specialized fitting
  • May need internal toricity in about 30% of cases 2

Hybrid Contact Lenses

• Useful for patients with RGP intolerance or fitting challenges
• Advantages:
  • Combine rigid center with soft skirt
  • Provide good centration and comfort
  • New-generation hybrid lenses show significant improvement in visual acuity compared to baseline uncorrected and spectacle-corrected VA 3
  • Easier fitting process similar to soft toric lenses 3
• Considerations:
  • May require multiple trial lenses for ideal fit (mean 1.4 lenses per patient) 3

Piggyback Systems

• RGP lens worn on top of a soft lens
• Useful when other options fail or for improved comfort
• Particularly helpful for high astigmatism or postoperative refractive error 1

Surgical Options

Corneal Cross-Linking (CXL)

• Primarily for preventing progression in ectatic disorders
• Has been demonstrated to retard or arrest progression of corneal ectasia 1
• Most effective when applied early in the disease process
• Does not necessarily improve irregular astigmatism but prevents worsening

Intrastromal Corneal Ring Segments (ICRS)

• FDA-approved under humanitarian device exemption for reducing irregular astigmatism in keratoconus
• Can be used off-label for correcting ectasia after keratorefractive surgery 1
• Advantages:
  • Spares the central cornea
  • Reversible (segments can be removed)
• Complications include segment malposition, migration, extrusion, and induced astigmatism 1

Excimer Laser Procedures

• For selected cases of irregular astigmatism
• Options include:
  • Phototherapeutic keratectomy (PTK) with masking agents
  • Topography-guided ablation
  • Wavefront-guided ablation
• Excimer laser assisted by sodium hyaluronate has shown improvement in corneal surface regularity and visual acuity in patients with surgically induced irregular astigmatism 4
• Caution: Patients should be evaluated using corneal topography/tomography before any keratorefractive surgery to identify irregular astigmatism that may be a sign of keratoconus or other ectatic conditions 1

Management Algorithm

1. Initial Assessment:

   • Determine cause of irregular astigmatism (keratoconus, post-surgical, trauma, etc.)
   • Evaluate severity using corneal topography/tomography
   • Assess higher-order aberrations (particularly vertical coma in keratoconus) 1

2. First-line Management:

   • For mild cases: Trial of spectacles if acceptable vision can be achieved
   • For moderate to severe cases: RGP contact lenses

3. If RGP lenses fail or are not tolerated:

   • Try scleral lenses (especially for severe irregularity)
   • Consider hybrid contact lenses
   • Evaluate for piggyback systems

4. Surgical considerations (if contact lens options fail):

   • For progressive ectasia: Corneal cross-linking
   • For stable irregular astigmatism: ICRS or topography/wavefront-guided laser procedures
   • For severe cases with poor visual potential: Consider corneal transplantation

Important Considerations

• Patients with keratoconus should be advised to halt eye rubbing, which has been associated with disease progression 1
• Contact lens wear requires careful monitoring for complications such as hypoxia, neovascularization, and infection 1
• Daily disposable lenses cause less damage to the ocular surface and less increase in proinflammatory cytokine levels compared to reusable lenses, but may not be suitable for highly irregular astigmatism 1
• Patients should be informed about the potential for night vision problems with any correction method 1
• For patients considering refractive surgery, careful evaluation with corneal topography/tomography is essential to identify irregular astigmatism that may indicate keratoconus or other ectatic conditions 1