Prescribing for Astigmatism: Early Use of Front Toric Optics in Scleral Lenses

Overview

Scleral lenses effectively neutralize corneal astigmatism and irregularities, with residual astigmatism being a key factor affecting visual outcomes. Incorporating front-surface toric optics early in the fitting process, supported by modern diagnostic technologies, can optimize vision and enhance patient satisfaction.

Background

Scleral lenses are valuable for correcting corneal surface astigmatism and irregularities. Residual astigmatism arises from lenticular and posterior corneal contributions and can be corrected by adding front-surface toricity after assessing lens rotation stability. Advances such as scleral profilometry enable earlier selection of toric back-surface lenses, improving fit precision. Addressing residual astigmatism early can reduce the number of lens orders and improve patient adherence.

Data Highlights

Conventional scleral lenses correct approximately 60% of higher-order aberrations (HOAs). Front toric optics are indicated when residual astigmatism is ≥0.75 DC and visual acuity improves significantly with spherocylindrical over-refraction. Lens flexure and decentration, though rare, can induce aberrations and should be managed to avoid confounding residual astigmatism assessment.

Key Findings

• Residual astigmatism significantly influences visual outcomes in scleral lens wearers.
• Front-surface toricity is typically added after confirming stable lens rotation but can be incorporated earlier with modern fitting technologies.
• Scleral profilometry allows accurate selection of toric back-surface lenses, improving initial fit.
• Lens flexure and decentration can mimic residual astigmatism and should be corrected before adding front toric optics.
• Front toric optics are recommended when residual astigmatism is ≥0.75 DC and subjective visual improvement is noted.
• Wavefront-guided optics can address residual higher-order aberrations in patients dissatisfied despite 20/20 acuity.

Clinical Implications

Clinicians should consider incorporating front-surface toric optics early in the scleral lens fitting process when residual astigmatism is clinically significant and visual improvement is evident. Utilizing advanced diagnostic tools like scleral profilometry facilitates precise lens selection and fit, reducing fitting time and improving patient satisfaction. Addressing lens flexure and decentration is essential to accurately identify true residual astigmatism.

Conclusion

Early incorporation of front toric optics in scleral lenses, enabled by technological advances, optimizes visual outcomes and enhances patient satisfaction by minimizing residual astigmatism. This approach streamlines the fitting process and supports better patient adherence.

References

1. Hastings et al, 2019 -- Comparison of wavefront-guided and best conventional scleral lenses after habituation in eyes with corneal ectasia
2. Nguyen et al, 2020 -- Case report: what are we doing for our “20/20 unhappy” scleral lens patients?