A Randomized Trial to Evaluate the Effect of Toric Versus Spherical Contact Lenses on Vision and Eyestrain

Wear Experiences with Two Soft Contact Lenses for Astigmatism of Different Modalities

Introduction

Patients expect to have excellent vision and comfort when wearing soft contact lenses. The purpose of this study was to compare the wear experiences of participants with astigmatism when wearing a daily disposable soft toric lens to an established, commonly used reusable toric lens.

Methods

In this crossover study, habitual soft toric lens wearers were fit with a daily replacement soft toric lens (delefilcon A) and a reusable, 1-month replacement soft toric lens (comfilcon A) in a randomized order. After 30 days of wear, Visual analog scale (VAS) surveys were used to assess wear experience, including vision and comfort, for overall wear and end-of-day wear. Scores were compared statistically with mixed-effects linear models. Participants also responded to questions about convenience, ease of use, and satisfaction with both lenses and preference questions based upon comfort, vision, and overall performance.

Results

Fifty-nine participants completed the multi-site crossover study. VAS scores [mean(std dev)] for overall quality of vision for the delefilcon A [80.4(16.4)] and comfilcon A [66.8(27.7)] lenses were statistically significant (P=0.002). The difference in the mean overall comfort scores for the delefilcon A lenses [71.6(26.3)] and comfilcon A lenses [63.2(28.9)] was 8.4, which exceeds the establish criteria for clinical significance, although not statistically significant (P=0.08). Overall satisfaction scores were 68.8(26.9) for the delefilcon A and 59.7(30.3) for the comfilcon A lenses (P=0.08). Both lenses provided mean binocular visual acuities better than 20/20 Snellen equivalent. Over half of the participants preferred the delefilcon A lenses based upon comfort, vision, and overall performance. Convenience, ease of use, and satisfaction all scored higher with delefilcon A lenses.

Conclusion

The results of this study show that wear experience with delefilcon A lenses for astigmatism can meet or exceed that of comfilcon A toric lenses while also providing healthy, daily disposable lens wear.

Clinical Investigation of Flat Pack Toric Contact Lenses and Wearer Attitudes to Environmental Impact

OBJECTIVES

To investigate the performance of a novel flat pack toric daily disposable contact lens compared with traditionally packaged toric lenses in a randomized, crossover study. Environmental attitudes to contact lens wear were also explored.

METHODS

Habitual contact lens wearers were recruited to wear a hioxifilcon A (Miru 1 day Flat Pack Toric, Menicon, Nagoya, Japan) test lens and a control lens: either nelfilcon A (Dailies AquaComfort Plus, Alcon, Geneva, Switzerland) or etafilcon A (1-Day Acuvue Moist, Johnson & Johnson, New Brunswick, NJ). Objective lens performance was assessed at fitting, and participants wore lenses in a randomized order for three consecutive days. Subjective measures of lens performance (comfort, vision, and handling) were then assessed by a questionnaire, with further questions on overall lens preference and environmental perceptions.

RESULTS

Objective measures of lens fit were similar for the test and control lenses, except for distance VA which was better with the control lenses ( P <0.05; difference of two logMAR letters). End of day comfort was greater with the test lens, but this did not reach significance. Both lenses demonstrated similar scores for overall satisfaction. 87.5% of participants indicated the environmental impact of contact lenses to be important/extremely important to them, with 100% of participants identifying the flat pack packaging as having a smaller environmental impact.

CONCLUSION

Overall, the lenses used in the study performed to similar levels. Environmental credentials are important to contact lens wearers, which may contribute to overall lens preference.

Optical Quality and Visual Performance With Different Toric Contact Lens Designs

OBJECTIVES

To evaluate the optical quality of different toric contact lens (CL) designs and compare their on-eye visual correction performance.

METHODS

Twenty soft CL wearers aged 20 to 39 years were enrolled. Two daily disposable silicone-hydrogel toric CLs were tested: the "Eyelid Stabilized Design" (ESD-CL) and prism-ballast design (PB-CL); a spherical daily disposable silicone hydrogel CL (spherical CL) was used as a control. On-eye performance was compared for corrected distance visual acuity (CDVA), astigmatism, and ocular higher-order aberrations (HOAs); astigmatism and ocular HOAs were measured with a wavefront sensor. The subjective quality of vision, rated for "blurred vision" and "double vision," lens rotation, and fitting were also compared.

RESULTS

The ESD-CLs, PB-CL, and no-CL provided better CDVA than spherical CL ( P <0.05). Compared with spherical CL and no CL, PB-CL and ESD-CLs caused significantly lesser astigmatism ( P <0.05). Coma was significantly lesser with ESD-CLs than that with PB-CL ( P <0.05); total HOAs did not differ among the four conditions. The subjective ratings for blurred and double vision were significantly lower with ESD-CLs than those with spherical CL ( P <0.05).

CONCLUSIONS

Toric CLs provide a better CDVA than spherical CLs. However, differences in coma and subjective symptoms may occur because of the design of toric CLs.

Visual discomfort and contact lens wear: A review

The purpose of this manuscript is to describe how vision influences contact lens discomfort and review the evidence supporting the hypothesis that contact lens discomfort can be caused by vision and vision-related disorders. Contact lens discomfort is a misunderstood and difficult to manage clinical condition. Most treatments and strategies aimed at alleviating discomfort focus on optimizing the contact lens fit and its relationship with the ocular surface, but these strategies commonly fail at relieving discomfort symptoms. Many vision and vision-related disorders share symptoms with those reported by uncomfortable contact lens wearers. This paper will review evidence and literature that describes how these vision and vision-related disorders may influence comfort in contact lens wearers. Acknowledging how vision influences contact lens discomfort will improve future research intended to better understand the condition, allow for more effective clinical management, and reduce rates of discontinuation.

Addressing common myths and misconceptions in soft contact lens practice

Advances in contact lens technology over the past 50 years since the commercialisation of the first soft lenses in 1971 have been incredible, with significant changes in contact lens materials, frequency of replacement, care systems and lens designs occurring. However, despite the widespread availability of contact lenses, penetration rates for those who need vision correction remain in the low single digits and many practitioners seem to hold on to concepts around the potential value of contact lenses that appear based in the dim and distant past and are certainly no longer valid today. This review addresses 10 common 'myths and misconceptions' around soft contact lenses using an evidence-based approach that can hopefully dispel some of these incorrect assumptions.

Does offering only the spherical contact lens trial to the low astigmats mislead the practitioners?

AIM

To compare the visual acuity (VA), comfort, and patient preference in a soft toric contact lens (TCL) versus soft spherical contact lens (SCL) in low astigmatic subjects during the contact lens (CL) trial.

METHODS

This subject-masked, block randomized, 2×2 crossover study recruited 40 neophyte subjects (80 eyes) aged 18 to 33y with astigmatism in the range of 0.75-1.25 D with or without spherical power from -6.00 D to +6.00 D. The participants were scheduled for two days CL trial and were fitted with the best-fit SCL and TCL. After 4h of wear, they were assessed objectively for high contrast VA and subjective vision, comfort, and preference.

RESULTS

The responses of 36 subjects (response rate 90%) with a mean age of 23.02±2.97y (range 18 to 33y) were analyzed. One-line improvement of monocular VA in the logMAR chart was reported to TCL as compared to SCL (-0.044±0.06 vs 0.04±0.03 logMAR, P=0.01) but the binocular vision remained similar (-0.12±0.07 vs -0.14±0.04 logMAR, P=0.38). Subjects felt a noticeable difference in clarity when shifted to TCL as compared to the SCL. The satisfaction with vision (vision quality) was significantly better with TCL (P=0.03). The fatigue with TCL was graded less at 2.5±0.6, compared to SCL at 4.6±1.3 (P=0.04). Thirty-three participants (91.6%) preferred to use contact lens of which 26 participants (79%) preferred TCL.

CONCLUSION

The findings suggest that VA and comfort are better with TCL as compared to SCL which is only observed if the patient was offered both offering SCL with spherical equivalent power alone as the first option can mislead the practitioner; TCL trial should be the first choice of the lens in low-to-moderate astigmatism.