Influence of periodic vs continuous daily bright light exposure on development of experimental myopia in the chick

Backhouse, Simon; Collins, Andrew; Phillips, J. R.

doi:10.1111/opo.12069

Cited by 37 publications

(33 citation statements)

References 48 publications

(66 reference statements)

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“…Short term bright light exposure for 1 or 2 hours generated only a trend towards inhibition of deprivation myopia. This result is consistent with a recent study in chickens in which bright light of 10 000 lux was provided for 2 hours a day but no significant effects were found, no matter at which time of the day it was applied [29]. In comparison, human studies show that children appear to be more “sensitive” to bright light exposure, as Jones et al observed a marked reduction in the risk of myopia when the amount of time outdoors increased from 0–5 hours per week (approximately 1 hour per day) to>14 hours per week (approximately 2 hours per day) [9].…”

Section: Discussionsupporting

confidence: 93%

“…On the other hand, no relative changes in corneal radius of curvature were found by Ashby et al [13] when animals were reared under 50, 500 or 15 000 lux. Also Backhouse et al [29] did not find relative changes in chickens kept at 2,000 lux for 10 hours or at 10,000 lux for 2 hours. Interestingly, Cohen et al [12] found that corneal radius of curvature responded differently under continuous light and under normal diurnal cycles.…”

Section: Discussionmentioning

confidence: 90%

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Intermittent Episodes of Bright Light Suppress Myopia in the Chicken More than Continuous Bright Light

2014

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PurposeBright light has been shown a powerful inhibitor of myopia development in animal models. We studied which temporal patterns of bright light are the most potent in suppressing deprivation myopia in chickens.MethodsEight-day-old chickens wore diffusers over one eye to induce deprivation myopia. A reference group (n = 8) was kept under office-like illuminance (500 lux) at a 10∶14 light∶dark cycle. Episodes of bright light (15 000 lux) were super-imposed on this background as follows. Paradigm I: exposure to constant bright light for either 1 hour (n = 5), 2 hours (n = 5), 5 hours (n = 4) or 10 hours (n = 4). Paradigm II: exposure to repeated cycles of bright light with 50% duty cycle and either 60 minutes (n = 7), 30 minutes (n = 8), 15 minutes (n = 6), 7 minutes (n = 7) or 1 minute (n = 7) periods, provided for 10 hours. Refraction and axial length were measured prior to and immediately after the 5-day experiment. Relative changes were analyzed by paired t-tests, and differences among groups were tested by one-way ANOVA.ResultsCompared with the reference group, exposure to continuous bright light for 1 or 2 hours every day had no significant protective effect against deprivation myopia. Inhibition of myopia became significant after 5 hours of bright light exposure but extending the duration to 10 hours did not offer an additional benefit. In comparison, repeated cycles of 1∶1 or 7∶7 minutes of bright light enhanced the protective effect against myopia and could fully suppress its development.ConclusionsThe protective effect of bright light depends on the exposure duration and, to the intermittent form, the frequency cycle. Compared to the saturation effect of continuous bright light, low frequency cycles of bright light (1∶1 min) provided the strongest inhibition effect. However, our quantitative results probably might not be directly translated into humans, but rather need further amendments in clinical studies.

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Section: Discussionsupporting

confidence: 93%

Section: Discussionmentioning

confidence: 90%

Intermittent Episodes of Bright Light Suppress Myopia in the Chicken More than Continuous Bright Light

2014

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“…Consistent with the previous findings of the effects of BL across multiple species, 10,14,[42][43][44] Figure 1 shows that BL (6 hours/day) shifted refraction toward hyperopia, and inhibited FDM development by at least 46% with corresponding changes in VCD and AL. Bright light exposure for less than 2 hours/day had no effect on FDM in chicks, and was only effective when exposure times were longer than 5 hours/day, suggesting that the duration of BL exposure is an important factor in myopia control.…”

Section: D1r (At Least Partially) Mediates Bl Inhibitory Effects On Rsupporting

confidence: 90%

Bright Light Suppresses Form-Deprivation Myopia Development With Activation of Dopamine D1 Receptor Signaling in the ON Pathway in Retina

Chen

Zhi

Ruan

et al. 2017

Invest. Ophthalmol. Vis. Sci.

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Citation: Chen S, Zhi Z, Ruan Q, et al. Bright light suppresses form-deprivation myopia development with activation of dopamine D1 receptor signaling in the ON pathway in retina. Invest Ophthalmol Vis Sci. 2017;58:230658: -231658: . DOI:10.1167 PURPOSE. To determine whether dopamine receptor D1 (D1R) signaling pathway activation by bright light (BL) in specific retinal neuronal cell types contributes to inhibiting formdeprivation myopia (FDM) in mice.METHODS. Mice (3-weeks old) were raised under either normal light (NL: 100-200 lux) or BL (2500-5000 lux) conditions with or without form deprivation. Refraction changes were evaluated with an eccentric infrared photorefractor, and ocular axial components with optical coherence tomography. The D1R antagonist, SCH39166, was intraperitoneally injected daily to evaluate if BL mediates declines in FDM development through D1R activation. Six different biomarkers of retinal neuronal types delineated differential distribution of D1R expression. cFos and phosphorylated tyrosine hydroxylase (p-TH) immunofluorescent staining evaluated D1R receptor activation and dopamine synthesis, respectively. CONCLUSIONS. Bright light increases D1R activity in the BCs of the ON pathway, which is associated with less myopic shift and ocular elongation than those occurring in NL. These declines suggest that increased D1R activity in the ON pathway contributes to the BL suppression of FDM development in mice.

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“…However, other potential variables, such as time of day of exposure, have not been sufficiently explored. Several recent studies hint that time of day might be important: 2 hours of bright light was more effective at myopia inhibition in form-deprived eyes when given mid-day versus evening (Backhouse et al 2013). Another study, however, showed that 5 hours of bright light was more effective in the morning than in the evening at reducing negative lens-induced myopia (Feldkaemper et al 2016).…”

Section: Discussionmentioning

confidence: 99%

Myopic defocus in the evening is more effective at inhibiting eye growth than defocus in the morning: Effects on rhythms in axial length and choroid thickness in chicks

Nickla

Thai

Trahan

et al. 2017

Experimental Eye Research

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Animal models have shown that myopic defocus is a potent inhibitor of ocular growth: brief (1–2 hours) daily periods of defocus are sufficient to counter the effects of much longer periods of hyperopic defocus, or emmetropic vision. While the variables of duration and frequency have been well-documented with regard to effect, we ask whether the efficacy of the exposures might also depend on the time of day that they are given. We also ask whether there are differential effects on the rhythms in axial length or choroidal thickness. 2-week-old chickens were divided into 2 groups: (1) “2-hr lens-wear”. Chicks wore monocular +10D lenses for 2 hours per day for 5 days at one of 3 times of day: 5:30 am (n=11), 12 pm (n=8) or 7:30 pm (n=11). (2) “2-hr minus lens-removal”. Chicks wore monocular −10D lenses continually for 7 days, except for a 2-hr period when lenses were removed; the removal occurred at one of 2 times: 5:30 am (n=8) or 7:30 pm (n=8). Both paradigms exposed eyes to brief myopic defocus that differed in its magnitude, and in the visual experience for the rest of the day. High frequency A-scan ultrasonography was done at the start of the experiment; on the last day, it was done at 6-hr intervals, starting at noon, over 24-hr, to assess rhythm parameters. Refractive errors were measured using a Hartinger’s refractometer at the end. In both paradigms, myopic defocus in the evening was significantly more effective at inhibiting eye growth than in the morning (“2-hr lens-wear”: X-C: −149 vs −83 μm/5d; “2-hr lens-removal: X-C: 91 vs 245 μm/7d; post-hoc Bonferroni test, p<0.01 for both). Data for “noon” was similar to that of “evening”. In general, the refractive errors were consistent with the eye growth. In both paradigms, a 2-way ANOVA showed that “time of day” accounted for the differences between the morning versus evening groups (“2-hr lens-wear”: p=0.0161; “2-hr lens-removal”: p=0.038). In the “plus-lens” morning exposure, the rhythm in axial length could not be fit to a sinusoid. In both paradigms, the rhythm in axial length for the evening group was phase-advanced relative to noon or morning (“2-hr lens-wear: evening vs noon; 1:24 pm vs 6:42 pm; “2-hr lens-removal: evening vs morning: 12:15 pm vs 6:18 pm; p<0.05 for both). Finally, the amplitude of the rhythm as assessed by the “day vs night” maximum and minimum respectively, was larger in the “evening” than in the “morning” group (“2-hr lens-wear: 88 vs 38 μm; “2-hr lens-removal: 104 vs 48 μm; p<0.05 for both). For the choroidal rhythm, there was no effect on phase, however, the amplitude was larger in most, but not all, experimental groups. These findings have potential translational applications to myopia prevention in schoolchildren, who are exposed to extended periods of hyperopic defocus during reading sessions, due to the nearness of the page. We propose that bouts of such near-work might best be scheduled later in the day, along with frequent breaks for distance vision.

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Influence of periodic vs continuous daily bright light exposure on development of experimental myopia in the chick

Cited by 37 publications

References 48 publications

Intermittent Episodes of Bright Light Suppress Myopia in the Chicken More than Continuous Bright Light

Intermittent Episodes of Bright Light Suppress Myopia in the Chicken More than Continuous Bright Light

Bright Light Suppresses Form-Deprivation Myopia Development With Activation of Dopamine D1 Receptor Signaling in the ON Pathway in Retina

Myopic defocus in the evening is more effective at inhibiting eye growth than defocus in the morning: Effects on rhythms in axial length and choroid thickness in chicks

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