A recent study published in Ophthalmic and Physiological Optics evaluated the role of astigmatism in myopic eye growth and elucidating the effectiveness of myopia control strategies.
Give me some background.
Following the COVID-19 lockdowns, studies have reported an increase in the prevalence and severity of both astigmatism and myopia—potentially indicating a shared effect of lifestyle and environment on refractive progression for both.
Plus: Both astigmatism and myopia have been associated with changes in choroidal thickness and vascular density suggesting similarities in the processes.
I’m sensing a but …
You sensed right. Despite this, the mechanism underlying the role of astigmatism in myopic eye growth remains unclear:
- On one hand: The sensitivity of the focusing mechanism is reduced in myopia, so chronic blur due to significant astigmatism may degrade further the eye’s ability to regulate emmetropization.
- On the other: It has been proposed that astigmatism may help facilitate emmetropization by providing cues to the sign of defocus, which then helps guide normal eye growth.
Now talk about the study.
In this study, investigators performed a scoping review in March 2025 and updated in August 2025 using MEDLINE and PubMed to explore two key associations:
- Aim 1: The impact of astigmatism on myopia prevalence, onset, and progression
- Aim 2: The impact of astigmatism on the effectiveness of myopia control interventions
Literature was initially screened by title, abstract, and finally by the relevance of the full manuscript.
In total: 47 studies were included in the analysis (Aim 1: 30, Aim 2: 17), with most conducted in Asia (n=31).
Findings?
Overall: A higher prevalence of astigmatism was associated with myopia, with myopia progression and astigmatism found to be potentially related.
However, with this determination, two notes should also be kept in mind:
- There is limited research on the effects of uncorrected astigmatism on the course of myopia.
- There is limited research regarding the influence of astigmatism on the effectiveness of myopia control strategies, with conflicting findings between studies.
Talk about the association between astigmatism and myopia.
While prior research has indicated that astigmatism in infancy and early childhood may precede myopia onset and progression in later years, findings haven’t clarified “whether astigmatism causes myopia directly or if astigmatic children become myopic due to shared environmental and lifestyle risk factors,” the study authors explained.
Moreover: Few studies have observed “an independent relationship between astigmatism and myopia progression, and none have found a causative role to explore if astigmatism does indeed play causative role in myopia progression (or vice versa) or if astigmatism is simply a biomarker of myopic eye growth,” they added.
And on the impact of myopia control therapies on astigmatism?
One study on myopia interventions found that astigmatic children wearing defocus incorporated multiple segments (DIMS) spectacles experienced greater myopic progression while another reported greater astigmatic progression in myopic children wearing highly aspherical lenslet (HAL) lenses.
Meaning: Optical interventions for myopia control may influence astigmatism directly.
How:
- DIMS lenses: Astigmatism may affect the uniformity of the peripheral blur induced by the DIMS lenses, reducing the effectiveness of the intervention
- HAL lenses: The slowing in spherical progression may promote an increase in astigmatism
Any limitations?
A few, including:
- This study did not formally appraise the quality of the evidence using a standardized assessment tool typically included in systematic reviews
- The diverse range of study designs and methodologies (13 longitudinal observational, 14 retrospective) impaired the comparability of findings
- How: Due to varying methods of measuring astigmatism, inclusion and exclusion criteria, and differences in how myopia was defined
- Some studies solely looked at the change in spherical equivalent refraction (SER) rather than sphere and cylinder individually—potentially masking the true effects of astigmatism and myopia.
Take home.
These findings suggest that myopia progression and astigmatism may be interdependent.
However: A causative role of astigmatism in promoting myopia has yet to be identified.
Next steps?
Prospective research in children of differing ethnicities with a range of astigmatism is required to determine if astigmatism influences the effectiveness of myopia control interventions.
Why: To provide an evidence base to inform clinical decision-making and management plans for myopic children with astigmatism, particularly in non-Asian populations where research is limited.