A novel ring-focus soft contact lens design for myopia control

Paper title: Randomized trial of soft contact lenses with novel ring focus for controlling myopia progression

Authors: Xu Cheng (1), Jie Xu (1), Noel Brennan (1)

1. Johnson & Johnson Vision

Date: October 2022

Reference: Cheng X, Xu J, Brennan NA. Randomized trial of soft contact lenses with novel ring focus for controlling myopia progression. Ophthalmol Sci 2022:Oct 18.
[Link to open access paper]

(Note that the image above does not depict the contact lens design - it's just a suitable image that we liked!)

This randomized controlled trial of soft contact lenses included three treatment groups and one control group wearing single vision. Two prototype designs with non-coaxial ring-focus were compared to a dual-focus (DF) design and single vision (SV). Almost 200 children aged 7 to 12 years with myopia -0.75 to -4.50D completed the multi-site study over 9 clinical sites in 3 countries. 

The novel soft contact lens design approach was to increase the add power in the contact lens without impacting vision. Studies on traditional center-distance multifocal soft contact lenses have shown a reduction in acuity with increasing add power.^1,2

To overcome this, the 'plus' power in the novel design does not generate coaxial point focus, instead creating a 'ring focus' in front of the retina, off the visual axis. Extensive optical table testing was used to undertaken 'proof of concept testing to develop two prototype lenses:

1. EE for enhancing efficacy"via introduction of a greater amount of plus power than conventional multifocal or dual-focus lens designs, while maintaining comparable visual performance" and
2. EV for enhancing vision "while maintaining similar myopia control efficacy to a standard dual-focus lens."

Both lenses featured "two concentric, annular zones with +7 D non-coaxial plus power for myopia control treatment, but these annular treatment zones in the EE lens were positioned closer to the center of the lens than for EV. EE also includes a +10 D co-axial treatment zone that was designed to further “boost” myopia control efficacy while limiting its impact on vision."

The participants' mean age was around 10 years with 36-39% being under 10 years of age. Average daily lens wearing time was similar across all groups at around 11 hours (at 1 week) and 12-13 hours at 26 weeks. There were no serious or significant adverse events during the study.

After 26 weeks (six months) all three myopia control soft contact lenses showed a reduction in axial growth compared to SV, but only EE showed a significant reduction in refractive change.

• EE showed 0.079mm growth, which was significantly less than DF
• EV showed 0.019mm growth, which was similar to DF
• DF showed 0.135mm growth, which was similar to EV
• SV showed 0.189mm growth.

An interesting aspect of this study design was that axial length was measured after 1, 4 and 13 weeks, as well as the 26 week endpoint. After only 4 weeks, the reduction in axial growth generated by the EE lens was statistically significant. All three myopia control designs showed lower growth at 13 weeks, increasing in magnitude by 26 weeks.

Analysis of potential predictive factors for the treatment effect of any of the lenses found no influence of baseline age, gender, refraction or mesopic pupil size. Only wearing time was significant, with longer wearing time leading to slower axial elongation.

Subjective vision responses showed that over 90% of participants reported being 'very happy' with their vision. Both EE and DF groups reported more haloes and other visual disturbances: at 1 week, haloes were reported in 12% which reduced to 5-7% after 26 weeks. EE showed less ghosting (2%) compared to DF (14%) at 26 weeks.

Measured visual acuity in all myopia control lens designs was not significantly different from 0.00 logMAR (6/6 or 20/20 equivalent) at all visits. More than 90% also achieved a centred lens fit.

The authors reported consistent myopia control effects for the EE lens when compared to previously published studies on soft contact lenses and ortho-k. The authors report that clinical trials with longer duration are underway.

• The non-coaxial ring-focus technology of the prototype lenses used in this study appears to offer potential performance advantages over traditional coaxial focus lenses, and may mitigate any trade-off between efficacy and visual quality with such design. 
• Axial length measurement by optical biometry was sensitive enough to detect efficacy at 4 weeks for EE and at 13 weeks for all of the myopia control lenses, where refractive error differences to SV were not statistically significant for EV and DF at 26 weeks. This indicates the importance of axial length measurement in determining myopia control efficacy.

1. Longer study duration is needed to see if the early leading performance of the EE lens is maintained compared to other designs.
2. When compared to the SV control group, axial length measurement detected myopia control efficacy after 4 weeks with the EE lens and after 13 weeks with all myopia control contact lenses. The potential to discern a statistically significant treatment effect by optical biometry within a 4-week period may have implications for lessening the burden of screening outcomes for myopia control prototype products. Studies which further investigate the correlation between short-term and long-term axial length efficacy results would be valuable. 

Title: Randomized trial of soft contact lenses with novel ring focus for controlling myopia progression

Authors: Xu Cheng, Jie Xu, Noel Brennan