by
Mamisoa Andriantafika
A study published in Cell Reports in 2026 proposes a new hypothesis about the mechanisms behind myopia: it may not be screens themselves that drive its development, but rather the reduction in light reaching the retina during prolonged near work in poorly lit indoor environments.
Researchers at SUNY College of Optometry (New York) show that pupil constriction linked to accommodation — the natural reflex that makes nearby images sharp — is more pronounced in myopes, further reducing retinal illumination.
Pupil constriction during near work indoors would reduce the light reaching the retina, thereby promoting myopia progression.
The study was conducted on 34 subjects (13 emmetropes and 21 myopes) using an electrically tunable lens inducing optical defocus of -5 diopters. Participants had to bring an image into focus by increasing their crystalline lens power — the process of accommodation. Researchers simultaneously measured eye vergence and pupil constriction at different contrast levels.
Key finding: both visuomotor functions increase with contrast, whether the stimulus is bright (ON pathway) or dark (OFF pathway). Contrast sensitivity is higher for dark stimuli (OFF pathway) than bright stimuli (ON pathway), which is the opposite of what is observed for simple visual detection.
Myopia has reached near-epidemic proportions. In Europe and the United States, it affects about half of all young adults; in some parts of East Asia, prevalence rates reach 90%. While genetic factors play a role, the rapid increase seen over just a few generations clearly points to environmental factors.
Among these factors, near-work activities — reading, smartphones, tablets — are often implicated. But this new hypothesis refines the reasoning: it is not the screen itself that is problematic, but the combination of sustained near-work effort in a poorly lit indoor environment. Such a situation reduces the amount of light reaching the retina, which may trigger the axial eye growth mechanisms responsible for myopia.
The rapid increase in myopia over just a few generations points to environmental factors, beyond genetic predisposition alone.
Myopes show stronger accommodative pupil constriction than emmetropes, further reducing the light reaching their retina.
The study demonstrates that in myopes, both eye vergence and accommodative pupil constriction are potentiated compared to emmetropes. Moreover, these responses progressively strengthen with repeated trials — a temporal potentiation significantly more pronounced in myopes.
Another important finding: myopes show an ON pathway deficit, reducing its dominance in accommodative vergence. Furthermore, the modulation of pupil constriction by eye blinks — a protective mechanism that activates the ON pathway — is impaired in myopes, potentially depriving their retina of additional light during natural visual rest periods.
This hypothesis may explain the effectiveness of several already-recognised prevention strategies: time spent outdoors (intense light even with a constricted pupil), positive defocus lenses, atropine (which dilates the pupil and thus increases retinal illumination), or contrast reduction. All reduce accommodative pupil constriction and/or increase retinal light.
If these results are confirmed, practical recommendations should go beyond simply limiting screen time: good lighting during indoor reading activities and regular outdoor breaks would be simple, accessible preventive measures to slow myopia progression in children.
