Control measures in China are ahead of US measures.
Myopia is constantly evolving, and this update focuses on comparing effectiveness of myopia control using different treatment methods, improving the level of control using orthokeratology (ortho-k), repeated low-density red light (RLRL) laser therapy, and work on pre-myopia. Unless otherwise stated, the studies reported below recruited children up to aged 13 years, with low to moderate myopia (³–5.00 D), astigmatism (≤ 1.50 D), and anisometropia (≤1.50 D).
Optical interventions such as ortho-k and myopia control soft contact lenses (MCSCL) and spectacles (MCS) are currently popular options for myopia control. The efficacy of ortho-k in slowing axial elongation (AE) has been reported to range from 30% to 56%.1 A meta-analysis concluded that ortho-k is the most effective optical treatment to retard AE.2 MCSCL have been reported to slow myopia (refraction) progression by 25% to 43% and AE by 27% to 28%over 24 months of intervention.3,4 MCS, such as defocus incorporated multiple segments (DIMS) spectacle lenses and lenses with aspherical lenslets, have also demonstrated significant myopia control effects.5,6
Several studies have shown that ortho-k can effectively slow AE in low to moderate myopes after 2 years of lens wear (AE:control, 0.57-0.69 mm, ortho-k 0.25-0.47 mm; control effect: 31.9%-56.1%).7-10 The level of control may be affected by various factors, including initial age, pupil size, corneal power, and change in corneal power.1
Investigation into the use of smaller back optic zone diameter (BOZD) ortho-k lenses for myopia control in 45 myopic children of Chinese ethnicity revealed that 2-year use of smaller, 5-mm BOZD lenses resulted in a smaller treatment zone diameter, which was associated with reduced AE, compared with those using 6-mm BOZD lenses (0.15 mm vs 0.35 mm).11
Increasing the compression factor may also improve the effectiveness of myopia control using ortho-k. Compared with ortho-k lenses with conventional compression factor (0.75-1.00 D), lenses with an increased compression factor (1.75 D) further slowed AE by 34% in 75 young participants.12 Another 2-year randomized study showed that combined 0.01% atropine and ortho-k therapy resulted in improved retardation of AE compared with ortho-k alone (0.17 vs 0.34 mm) in 96 Chinese children.13 Using ortho-k lenses with an aspheric base curve also resulted in improved retardation of AE in Chinese children compared with lenses with a spherical base curve (0.19 vs 0.29 mm).14
Lam et al3 reported a 2-year, double-blind, randomized controlled trial in which 221 children were randomly assigned to the defocus incorporated soft contact (DISC) or single-vision contact lens group. Myopia was found to progress 25% more slowly in the DISC group compared with the control group (0.30 D/year vs 0.40 D/year). In addition, smaller AE was found in subjects wearing DISC lenses (0.13 mm/year vs 0.18 mm/year). The treatment effect correlated positively with DISC lens wearing time.
Another 2-year, prospective, longitudinal, nonrandomized study showed that children wearing soft radial refractive gradient (SRRG) contact lenses showed significantly smaller AE compared with the single-vision control group (0.38 mm vs 0.52 mm).4 In terms of AE, myopia control effect was comparable between SRRG lenses and ortho-k lenses in myopic children and adolescents (0.38 mm vs 0.32 mm).4
Lumb et al15 evaluated the experience of children wearing omafilcon A contact lenses (MiSight 1 Day; CooperVision), a dual-focus multifocal soft contact lens, in a 6-year clinical trial and reported that the children adapted rapidly to full-time wear, rated lenses highly, and rarely reported issues.
Lam et al16 reported results of 36 children who had worn DIMS for 6 years. The spherical equivalent refraction (SER) and AE showed no significant differences in the first and last 3 years (SER: –0.52 ± 0.66 and –0.40 ± 0.72 D, respectively; AE: 0.32 ± 0.26 mm and 0.28 ± 0.28 mm, respectively [all, P > .05]). This was a continuation of their earlier study in which a total of 183 Chinese children, aged 8 to 13 years, completed a 2-year, double-masked, randomized controlled trial.5 They reported that DIMS lenses slowed SER by 52% and AE by 62%.
Using lenses with highly aspherical lenslets, Bao et al6 reported retardations of SER and AE by 55% and 51%, respectively, over 2 years in 157 children.
A randomized, placebo-controlled, double-masked, clinical trial conducted from June 2018 to September 2022 was conducted on 187 US children of different ethnicities, to compare 0.01% atropine eye drops with placebo for slowing myopia progression.17 Atropine eye drops administered nightly did not slow myopia progression (in terms of change in refraction and AE) compared with children receiving placebo. Adjusted between group difference in mean SER change and AE after 30 months were –0.04 D (95% CI, –0.25 to 0.17 D) and +0.009 mm (95% CI, –0.115 to 0.134 mm), respectively.17
In another randomized, 3-year clinical trial on 142 Chinese children, Zhu et al18 evaluated the effect of 0.05% atropine on myopia control for 2 years (phase 1) and withdrawal effect for 1 year, after ceasing the use of atropine (phase 2). They reported that the use of 0.05% atropine for 2 consecutive years may effectively control AE (0.26 vs 0.76 mm) and myopia progression (–0.46 vs –1.72 D), without significant rebound effect (SER progression) after atropine withdrawal (–1.32 vs –1.48 D).
Yam et al19 enrolled 474 non-myopic children and reported that, compared with placebo, nightly use of 0.05% atropine for 2 years resulted in a significantly lower myopia incidence and a reduced percentage of participants with rapid myopic shift. However, no significant differences were found with 0.01% atropine.
A recent meta-analysis, including 64 studies, also reported that 0.01% atropine was inferior to ortho-k (1 year) and MCS (1 year) with respect to retardation of AE.2
In recent years, attention has also focused on the treatment for pre-myopic children, with myopia considered as a disease. Although high myopia can result in various ocular pathologies and even vision loss, the majority of cases did not reach pathologic levels and can be treated with corrective lenses or refractive surgery. Thus, there are ophthalmologists who believe that considering myopia as a disease may not be appropriate for a condition that does not seriously affect most patients.20 Moreover, even if myopia is considered a disease, is it appropriate to prescribe invasive treatment before myopia has manifested?
A randomized, double-masked, placebo-controlled crossover trial was carried out in 60 pre-myopic children aged 6 to 12 years with cycloplegic SER greater than –0.75 D and less than or equal to +0.50 D in both eyes.21 The study reported that 0.01% atropine eye drops effectively prevented myopic shift, AE, and myopia onset in these children. However, does this suggest that children have to apply atropine eye drops until aged 14 to 16 years, when myopia may stabilize?22
Recently, repeated low-level red light (RLRL) laser therapy has been claimed to be a successful myopia prevention treatment. This therapy targets neuronal energy metabolism, which may be a major target for neurotherapy of myopia.23 The therapy involves directing a red laser beam onto the macula. However, there is a lack of studies on potential molecular changes and safety of prolonged use.Damage caused by RLRL may not be easily detected and difficult, if possible, to reverse. Additionally, as the device is used at home, nonadherence and misuse may lead to serious ocular problems.
Dong et al24 reported that RLRL therapy with 100% power significantly reduced myopia progression over 6 months compared with a sham device with only 10% of the original power (AE: 0.02 vs 0.13 mm). They reported no treatment-related adverse effects in 112 Chinese children. He et al25 conducted a 12-month, parallel-group, school-based, randomized clinical trial in 139 children with pre-myopia (SER: –0.50 to 0.50 D in the more myopic eye and having at least 1 parent with SER less than or equal to –3.00 D) in grades 1 to 4, and reported RLRL laser therapy to be well accepted by the children. The children received two 3-minute exposures (at least 4 hours apart) to red light daily for 5 days per week and the therapy was reported to result in a 54.1% reduction in myopia incidence. However, retinal damage, including darkened fovea with hypoautofluoresence of the macula in both eyes and bilateral foveal ellipsoid zone disruption and interdigitation zone discontinuity, in a 12-year-old girl after 5 months of RLRL laser therapy, has recently been published.26 Partial recovery was achieved 3 months after discontinuation of the therapy.
RLRL is delivered by a desktop device emitting red light at 650 nm and was originally certified as a class IIa device for treating amblyopia by the China National Medical Products Administration.27 However, since the publication of the case report of macula damage,26 serious concerns on its safety were raised, resulting in reclassification of the device to a class III medical device. Since ByJuly 2024, RLRL devices that have not obtained a class III medical device registration certificate cannot be produced or sold(China Food and Drug Administration Comprehensive Instrument Registration Letter [2023] No. 354).
A final important consideration is that myopia control treatments in children are long-term commitments, lasting until the mid-teens. These treatments may also involve complex, expensive, and time-consuming responsibilities, so serious thought should be given to whether the treatment is necessary. Careful consideration of the benefits of long-term treatment are required before burdening parents with guilt, high costs, or long-term responsibilities, such as monitoring contact lens/ortho-k wear and care.28