Seasonal efficacy variation in ortho-k and defocus spectacles

Paper title: Comparison of Seasonal Variation in Myopia Progression: Defocus Incorporated Multiple Segment Spectacle Lenses in Combination with 0.01% Atropine vs Orthokeratology

Authors: Xiaoxiao Li (1,2,3), Chenpei Zhao (2,3,4), Min Yin (2,3,4), Yanan Ji (1,2,3), Jungang Wang (1,2,3), Ju Zhang (1,2,3), Lin Leng (2,3,4)

1. Eye Institute of Shandong First Medical University, Eye Hospital of Shandong First Medical University (Shandong Eye Hospital), Jinan, Shandong, People's Republic of China.
2. State Key Laboratory Cultivation Base, Shandong Key Laboratory of Eye Diseases, Qingdao, Shandong, People's Republic of China.
3. School of Ophthalmology, Shandong First Medical University, Jinan, Shandong, People's Republic of China.
4. Eye Institute of Shandong First Medical University, Qingdao Eye Hospital of Shandong First Medical University, Qingdao, Shandong, People's Republic of China.

Date: Feb 2026

Reference: Li X, Zhao C, Yin M, Ji Y, Wang J, Zhang J, Leng L. Comparison of Seasonal Variation in Myopia Progression: Defocus Incorporated Multiple Segment Spectacle Lenses in Combination with 0.01% Atropine vs Orthokeratology. Clin Ophthalmol. 2026 Feb 20; 20:582774.

[Link to open access paper]

Seasonal variation in myopia progression is well recognised, with faster growth typically seen in winter periods. However, it is unclear whether commonly prescribed myopia control treatments reduce or eliminate this pattern. 

This retrospective cohort study examined whether eye growth differs between winter and summer in children using orthokeratology (OK) or defocus spectacle lenses combined with low‑dose atropine.

Clinical records from 428 children aged 7–13 years (baseline myopia -0.50 to -6.00D) who had attended a specialist eye hospital in northern China were reviewed. Children either wore OK lenses overnight (OK group, n=225) or used defocus spectacle lenses during the day with nightly 0.01% atropine (DIMSA group, n=203). Axial length was measured every three months for one year using optical biometry. Each six‑month interval was classified as “summer” or “winter” based on the midpoint between visits.

Key findings were as follows

• Both treatments produced similar overall slowing of eye growth across the year (DIMSA, 0.18mm; OK, 0.19mm).
• Axial elongation was around twice as fast in winter as in summer in both groups (DIMSA, 0.12mm vs 0.06mm; OK 0.13mm vs 0.06mm).
• Seasonal sensitivity differed between treatments where winter-summer differences were seen in the 7-8yr age group in the DIMSA group, but persisted from age 7-12yrs in the OK group.
• Children with shorter or average axial lengths (<26mm) showed clear seasonal variation, while those with longer eyes (≥26 mm) did not.
• Changes in refractive error did not show meaningful seasonal differences in the defocus‑plus‑atropine group.

In this study, both orthokeratology and defocus spectacle lenses plus low‑dose atropine showed similar overall annual control of axial elongation, yet neither fully removed the underlying seasonal pattern of faster winter progression. Overall, seasonal patterns persisted despite treatment, suggesting environmental factors continue to influence eye growth even when optical and pharmaceutical control strategies are used.

For eyecare practitioners, this means that fluctuations in progression across the year may reflect predictable seasonal variation rather than changes in treatment effectiveness. Faster winter progression should not automatically be interpreted as treatment failure, and slower summer progression should not be over‑interpreted as enhanced control.

These findings support the value of season‑aware monitoring. Shorter review intervals during winter may help identify faster progression earlier, particularly in younger children and those with shorter baseline axial lengths. However, the study does not provide evidence that treatment intensity should be altered by season, nor does it identify specific behavioural strategies that may counteract winter acceleration.

Discussing seasonal variation with families can help set realistic expectations. Understanding that progression may naturally speed up in winter can reduce unnecessary concern of treatment failure.

This study was retrospective and based on clinical records, meaning there was no objective measurement of children’s daily behaviours such as outdoor time, near work or screen use. As a result, it is not possible to determine whether the observed winter acceleration in axial elongation could be influenced by specific lifestyle patterns, or whether it represents a seasonal trend that persists even under typical myopia control management.

The age‑related differences in seasonal sensitivity also require further investigation. Seasonal variation persisted across a wider age range in the orthokeratology group than in the defocus‑plus‑atropine group, but the study design does not allow the relative contribution of lens design, atropine, or unmeasured behavioural factors to be separated. Without an atropine‑plus‑orthokeratology group, the reasons for these differing age patterns remain unclear.

The study also does not address whether treatment approaches should be modified according to season. While the authors note that additional control measures might be considered during winter, no specific strategies were evaluated, and there is no evidence that seasonal intensification of treatment would improve outcomes. Prospective studies with randomisation, objective behavioural tracking and comparison of multiple treatment combinations are needed to clarify mechanisms and determine whether season‑specific adjustments are justified.

Purpose: To investigate and compare seasonal variations in axial length (AL) in myopic children with defocus incorporated multiple segments (DIMS) spectacle lenses combined with 0.01% atropine (DIMSA) and orthokeratology (OK) lenses.

Methods: The present retrospective study involved 428 subjects, mean age 9.70 ± 1.94 years, categorized into two groups: DIMSA (203 cases), and OK lenses (225 cases). Data were classified as "summer" or "winter" based on the midpoint of the 6 months between visits. Initial clinical visit (baseline) and one-year follow-up data were collected, and only data from the right eye was retrieved for analysis. Axial elongation over time and between groups was analyzed.

Results: The mean change in AL at 1 year was 0.18 ± 0.19 mm in the DIMSA group and 0.19 ± 0.15 mm in the OK group, with no significance between the two groups (p>0.05). In both groups, the change of AL in winter was significantly higher than that in summer (P<0.01). A similar seasonal pattern was found among children 7-8 years of age in the DIMSA group and 7-12 years of age in the OK group, as well as for those with an initial AL < 26 mm.

Conclusion: DIMSA and OK lenses show similar reductions in myopia progression at different times of the year. Axial elongation decreased in summer, and this phenomenon disappears with increasing age and AL.

[Link to open access paper]