This article was originally published in a sponsored newsletter.

We have a great opportunity to provide better vision for our patients by correcting astigmatism. I’d like to provide an example from a recent case: an established 23-year-old contact lens wearer presented for an eye exam and contact lens fitting. Refraction demonstrated 0.75D of astigmatism OD and 0.50D of astigmatism OS. If this was your patient, would you reach for a toric lens for the right eye or fit spherical lenses in both eyes

Patients Who Can Benefit

Typically, 0.75D is the threshold to correct astigmatism and there are many different options for correction with contact lenses including soft toric, corneal GP, hybrid, and scleral lenses.

A study from Young, Sulley, and Hunt analyzed a database of 11,624 spectacle prescriptions to provide an estimate of the number of soft contact lens wearers who necessitate astigmatism correction.¹ Results showed that 47% of patients had astigmatism of 0.75D or greater in one eye and 24% had astigmatism of 0.75D or greater in both eyes, which indicated that astigmatic correction in contact lenses may benefit almost one in three contact lens wearers.¹ Importantly as well, binocular astigmatism is more common in myopes than hyperopes (32% vs 16%).

Visual Acuity Improvements with Toric Lenses

When toric lenses are fit to correct astigmatism of ≥ 0.75D, both subjective vision and visual acuity improve compared to spherical lenses.² Individuals with low astigmatic correction (0.75D to 1.00D) had an improvement between 3 and 5.5 letters of visual acuity when corrected with a toric contact lens compared to a spherical lens of the same material.³ With toric lenses, individuals who had moderate astigmatic eyes (1.25D to 2.00D) were able to gain between 8 and 12.5 letters of acuity compared to a spherical lens of the same material.³Further, toric lens wearers reported improved visual clarity and satisfaction with their correction, and most individuals (72%) favored a toric lens compared to a spherical lens.⁴

Dealing with Dropout

According to a literature review on the most frequent reasons for contact lens dropout, discomfort (i.e., dryness or irritation) was most common in established wearers and vision dissatisfaction was most common in new wearers.⁵ For new wearers, the first two months are essential: 50% of wearers drop out of contact lenses in the first two months and 26% of new wearers drop out of contact lenses by one year.⁵

We can combat these rates by fitting toric lenses in addition to optimizing the ocular surface and contact lens edge design. Most state-of-the-art toric lenses perform well and provide good vision to prevent contact lens dropout.²

I also find it helpful to follow up with patients in a week or two with an in-person visit, a text, or a quick call. If the contact lenses are not working well, I offer a new design or technology. Not only will this follow up prevent contact lens dropout, but it is also a great practice-building opportunity.

Returning to Our Case Example

For the 23-year-old patient I mentioned earlier, I demonstrated a quick check in the phoropter of the spectacle prescription with and without astigmatism, and the patient preferred the astigmatism correction in the right eye. Next, I fit the patient with a toric lens in the right eye and a spherical lens in the left eye. The patient reported improved vision and good comfort with this contact lens combination.

Which of your patients might be a good fit for toric lenses?

REFERENCES

1. Young G, Sulley A, Hunt C. Prevalence of astigmatism in relation to soft contact lens fitting. Eye Contact Lens. 2011 Jan;37:20–25.

2. Richdale K, Cox I, Kollbaum P, et al. CLEAR - Contact lens optics. Cont Lens Anterior Eye. 2021 Apr;44:220-239.

3. Richdale K, Berntsen DA, Mack CJ, Merchea MM, Barr JT. Visual acuity with spherical and toric soft contact lenses in low- to moderate-astigmatic eyes. Optom Vis Sci. 2007 Oct;84:969–975.

4. McIlraith R, Young G, Hunt C. Toric lens orientation and visual acuity in non-standard conditions. Cont Lens Anterior Eye. 2010 Feb;33:23–26.

5. Pucker AD, Tichenor AA. A Review of Contact Lens Dropout. Clin Optom (Auckl). 2020 Jun;12:85-94.

Melissa Barnett, OD, FAAO, FSLS, is the director of optometry at the University of California, Davis in Davis, specializing in anterior segment disease and specialty contact lenses. She is the past president of the Scleral Lens Education Society. She is an advisor to and/or has received honoraria or travel expenses from AccuLens, Alcon, Allergan, Bausch + Lomb, Bruder, Contamac, CooperVision, Johnson & Johnson Vision, Ocusoft, ScienceBased Health, Shire, Tarsus, and Visus Therapeutics.