Features

Truth or myth: Spectacle lenses provide better visual acuity than soft toric contact lenses?

Contact lenses Lenses
This month, in our series looking at common myths concerning contact lenses, Stephanie Wong and David Ruston consider soft torics

An international survey conducted from 2007 to 2011 assessed the prescribing practice of eye care practitioners in 39 countries. Soft spherical contact lenses (CL) were fitted three times more often than toric lenses. A wide variation in prescribing was reported between countries, with toric soft CLs accounting for only 6% of fits in Russia, compared with 48% in Portugal.1

More recently, a 2022 survey analysed the prescribing habits in 28 countries and reported that soft toric CL were prescribed in 28% of fits.2 Only one country, Israel, fits toric CLs greater than 40% of the time, which is the expected amount based on the prevalence of astigmatism at ≥0.75D.2 A lack of toric lens prescribing may be caused by multiple factors, including ethnic variations in prevalence of astigmatism.1

Practitioners may also contribute to this problem by failing to inform patients about toric CLs,3 the belief that high modulus spherical CL can mask astigmatism,4 the preconceived notion that lenses will rotate5 and cause poor vision,4 assuming that the fitting process will be lengthy,1 and due to varying levels of training.1,2

A lack of patient awareness about astigmatism, availability of toric CL,3 and the higher cost compared to spherical CL1,3 also reduces the likelihood of prescribing.

 

Professional Belief Survey Results

A recent survey of 1028 eye care professionals (ECPs) conducted in 2021 in Russia and in 2022 for the other markets, assessed the prescribing beliefs of ECPs in all six countries.6 Globally, on average 43% of respondents agreed that ‘toric soft CLs provide the same or better visual acuity (VA) as spectacles’.

The levels of agreement varied, ranging from 29% in South Korea to 53% in China (figure 1).6 The lowest level of agreement was in South Korea, where only 29% of practitioners believed that toric CLs have the same or better VA as spectacles (figure 1).6 These results indicate a lack of awareness of how toric CLs can successfully correct astigmatism.

 

 Figure 1: Results showing extent of agreement (shown in blue) or disagreement (shown in red) with the statement ‘Toric soft contact lenses provide the same or better visual acuity as spectacle lenses’. Data is from 2022 for all markets except Russia which is from 2021

What the Evidence Shows

Much research has gone into the comparison of vision between soft toric CLs and spectacles. Testing of the first daily disposable toric CLs revealed 88% of participants saw at least +0.10 logMAR (Snellen 20/25) and that vision with both spectacles and toric CLs were rated as excellent.7

When both neophytes and discontinued CL wearers with ≤3.00D of astigmatism were fit with a toric daily disposable hydrogel or two-weekly silicone hydrogel lens, similar levels of monocular and binocular distance VA were achieved compared to spectacles.3 Average monocular VA was within one letter of 0.00 logMAR (Snellen 20/20), and binocular VA was approximately half a line better than 0.00 logMAR with the CLs.3

Significantly worse binocular distance VA was found when astigmatism was ≥1.50D however, those with high amounts of astigmatism still achieved binocular VA of -0.02 LogMAR compared to -0.07 LogMAR (2.5 letter difference) for those with less astigmatism. Most participants subjectively rated vision as good, very good or excellent with spectacles (91%) and CLs (93%).

These findings are supported by other research assessing different toric hydrogel5,7 and silicone hydrogel CLs.4,8 No difference in high-contrast4,5,7,8 or low-contrast distance VA4,5,8 was found between CLs and spectacles. High-contrast distance VA remained the same between the two forms of correction under photopic and mesopic conditions,8 and was unaffected by pupil size.5 Near VA was also similar under high and low-contrast conditions.4

 

Conclusion

Soft toric CLs can provide the same or better levels of VA as spectacles.9 Additional advantages of CLs over spectacles include a wider field-of-view, increased image size for myopic prescriptions, reduced peripheral distortion, improved cosmesis, and decreased risk of breakage while playing sports.9

In view of these findings, toric CLs should always be recommended to patients with astigmatism seeking CLs, knowing that toric CLs can provide equivalent or better visual performance than spectacle lens correction. 

  • Dr Stephanie Wong is a clinical scientist at the Centre for Ocular Research & Education, School of Optometry & Vision Science, University of Waterloo. David Ruston is a director of global professional education at Johnson & Johnson Medical Ltd.

 

References

  1. Morgan PB, Efron N, Woods CA, et al. An international survey of toric contact lens prescribing. Eye Contact Lens. 2013;39(2):132-7.
  2. Morgan PB, Woods CA, Tranoudis IG, et al. International contact lens prescribing in 2022. Contact Lens Spectrum. 2023; 38: 28-35.
  3. Sulley A, Young G, Lorenz KO, et al. Clinical evaluation of fitting toric soft contact lenses to current non-users. Ophthalmic and Physiological Optics. 2013;33(2):94-103.
  4. Gaib SN, Vasudevan B. Low toric soft contact lens acceptance study. Contact Lens & Anterior Eye. 2015;38(3):194-198.
  5. Morgan PB, Efron SE, Efron N, et al. Inefficacy of aspheric soft contact lenses for the correction of low levels of astigmatism. Optometry and Vision Science. 2005;82(9):823-828.
  6. Johnson & Johnson Vision Care. Online survey of 1028 Eye Care Professionals across United States, United Kingdom, Russia, China, Japan and South Korea. Data on file 2021 (Russia) and 2022 (other markets).
  7. Grzesik M, Sickenberger W, Moest P, et al. Performance evaluation of a toric daily disposable contact lens. Optician. 2005;229(6004):22-24, 26.
  8. Carballo-Alvarez J, Mari-Ribas M, Martin-Gonzalez A, et al. Is soft toric contact lenses fitting a feasible option to improve optical quality and visual performance in corneal ectasia? Contact Lens & Anterior Eye. 2022;45(2):101434.
  9. Efron N, Henriquez A, Merkx JTM, et al. Why fit contact lenses? Optician. 992;204(5367):12-14.