Effects of mild‐ and moderate‐intensity illumination on short‐term axial length and choroidal thickness changes in young adults

Chakraborty, Ranjay; Baranton, Konogan; Spiegel, D.; Lacan, P.; Guillon, Matthias; Barrau, Coralie; Villette, Thierry

doi:10.1111/opo.12988

Cited by 15 publications

(23 citation statements)

References 68 publications

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“…In such experiments, the measured short-term changes in axial length (as determined from the corneal apex to the vitreo-retinal interface) result from changes in choroidal thickness: axial eye shortening based on choroidal thickening and axial elongation based on choroidal thinning [22,23]. It has been hypothesized by Wallman et al that changes in choroidal thickness may represent "a third mechanism of focusing the eye" as it can move the photoreceptor plane closer the focal plane [10].…”

Section: Introductionmentioning

confidence: 99%

“…It has been shown that the mechanism of emmetropization can be studied in short-term experiments by measuring the miniature changes in axial length and choroidal thickness that are induced by defined visual stimulation (range minutes to hours), both in animal models and human subjects [ 15 – 21 ]. In such experiments, the measured short-term changes in axial length (as determined from the corneal apex to the vitreo-retinal interface) result from changes in choroidal thickness: axial eye shortening based on choroidal thickening and axial elongation based on choroidal thinning [ 22 , 23 ]. It has been hypothesized by Wallman et al that changes in choroidal thickness may represent “a third mechanism of focusing the eye” as it can move the photoreceptor plane closer the focal plane [ 10 ].…”

Section: Introductionmentioning

confidence: 99%

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Imposed positive defocus changes choroidal blood flow in young human subjects

Świątczak

Schaeffel

Calzetti

2022

Graefes Arch Clin Exp Ophthalmol

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Purpose It has previously been found that imposing positive defocus changes axial length and choroidal thickness after only 30 min. In the present study, we investigated whether these changes may result from an altered choroidal blood flow. Methods Eighteen young adult subjects watched a movie from a large screen (65 in.) in a dark room at 2 m distance. A 15-min wash-out period was followed by 30 min of watching the movie with a monocular positive defocus (+ 2.5D). Changes in axial length and ocular blood flow were measured before and after the defocus, by using low-coherent interferometer (LS 900, Haag-Streit, Switzerland) and a laser speckle flowgraphy (LSFG) RetFlow unit (Nidek Co., LTD, Japan), respectively. Three regions were analyzed: (1) the macular area, where choroidal blood flow can be measured, (2) the optic nerve head (ONH), and (3) retinal vessel segments. Results Changes in choroidal blood flow were significantly and negatively correlated with changes in axial length that followed positive defocus in exposed eyes (R = − 0.67, p < 0.01). The absolute values of changes in choroidal blood flow in the defocused eyes were significantly larger than in the fellow control eyes (2.35 ± 2.16 AU vs. 1.37 ± 1.44 AU, respectively, p < 0.05). ONH and retinal blood flow were not associated with the induced changes in axial length. Conclusions Positive defocus selectively alters choroidal, but not retinal or ONH blood flow in young human subjects after short-term visual exposure. The results suggest that blood flow modulation is involved in the mechanism of choroidal responses to optical defocus.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Imposed positive defocus changes choroidal blood flow in young human subjects

Świątczak

Schaeffel

Calzetti

2022

Graefes Arch Clin Exp Ophthalmol

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“…However, illuminance measured in the shade was still >4000 lux, which is above the range of indoor illumination [71][72][73] and exceeds the illuminance levels used in previous studies that examined changes in choroidal thickness with increased light exposure in humans. [34][35][36] In summary, this study showed that spending time outdoors in sunlight induced choroidal thinning, which recovered by 2 h after returning indoors. Retinal exhibits differential responses under different environments, with greater thinning the photoreceptor outer segment + RPE and greater thickening in the photoreceptor inner segment during outdoor exposure compared with indoor illumination and darkness.…”

Section: Discussionmentioning

confidence: 53%

“…34 Furthermore, exposure to 1000 lux for 2 h in the morning induced an increase in choroidal thickness compared with darkness. 35 In contrast, exposure to 1000 lux for 4 h before sleep for 5 nights resulted in a decrease in subfoveal choroidal thickness. 36 Although the choroid has been implicated in the mechanism underlying the effect of light exposure on refractive development, 29,37 how the choroid responds during time outdoors in sunlight has not been examined previously.…”

Section: O R I G I N a L A R T I C L Ementioning

confidence: 95%

The outdoor environment affects retinal and choroidal thickness

Lou

Ostrin

2023

Ophthalmic Physiologic Optic

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Accumulating evidence suggests that time outdoors is protective against myopia development and that the choroid may be involved in this effect. The goal of this study was to examine the effect of 2 h of time outdoors in sunlight on retinal and choroidal thickness in adults. Methods: Twenty adults, ages 23-46 years, each participated in three experimental sessions on different days, consisting of 2 h of exposure to (1) indoor illumination (350 lux), ( 2) darkness (<0.1 lux) or (3) outdoor environment (6000-50,000 lux). Spectral-domain optical coherence tomography (SD-OCT) imaging was conducted at baseline, after 1 and 2 h of exposure, and after 1 and 2 h of follow-up. Choroidal, total retinal, photoreceptor outer segment + retinal pigment epithelium (RPE) and photoreceptor inner segment thicknesses were determined. Results: At 2 h, the choroid was significantly thinner during the outdoor compared with the indoor and dark conditions (p < 0.01) but was not significantly different at follow-up. Total retinal thickness was significantly thicker during and after the outdoor compared with the indoor and dark conditions. The outer segment + RPE was significantly thinner during the outdoor compared with the indoor condition but was not significantly different at follow-up. The inner segment was significantly thicker during the outdoor compared with the indoor and dark conditions during exposure and follow-up. Conclusions: Spending 2 h outdoors under high-intensity sunlight resulted in an unexpected thinning of the choroid, which recovered post-exposure. Retinal thickness showed different responses to the outdoor and indoor environments and was sensitive to the duration of exposure. K E Y W O R D S choroid, light exposure, myopia, outdoor time, retina

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“…It had been confirmed by others that the small changes in axial length trace back to changes in choroidal thickness (i.e. 25 ) which, in turn, can predict future changes in eye growth and myopia development (i.e. 26 ).…”

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confidence: 82%

Myopia: why the retina stops inhibiting eye growth

Świątczak

Schaeffel

2022

Sci Rep

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In myopia, the eye grows too long, and the image projected on the retina is poorly focused when subjects look at a distance. While the retina normally controls eye growth by visual processing, it seems to give up during myopia development. But what has changed? To determine whether the sharp image is in front or behind the retinal plane, a comparison of image sharpness in red and blue would provide a reliable cue because focal planes are about 1.3 D apart due to longitudinal chromatic aberration (LCA). However, up to now, it could not be demonstrated that the retina does, in fact, such a comparison. We used a new approach: movies were digitally filtered in real time to present either the blue channel of the RGB color format unfiltered while green and red were blurred (“blue in focus”), or the red channel was unfiltered while green and blue were blurred (“red in focus”) accordingly to the human LCA function. Here we show that, even though filtered movies looked similar, eyes became significantly shorter when the movie was sharp in the red plane but became longer when it was presented sharp in the blue plane. Strikingly, the eyes of young subjects who were already myopic did not respond at all—showing that their retina could no longer decode the sign of defocus based on LCA. Our findings resolve a long-standing question as to how the human retina detects the sign of defocus. It also suggests a new non-invasive strategy to inhibit early myopia development: keeping the red image plane on a computer screen sharp but low pass filtering the blue.

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Effects of mild‐ and moderate‐intensity illumination on short‐term axial length and choroidal thickness changes in young adults

Cited by 15 publications

References 68 publications

Imposed positive defocus changes choroidal blood flow in young human subjects

Imposed positive defocus changes choroidal blood flow in young human subjects

The outdoor environment affects retinal and choroidal thickness

Myopia: why the retina stops inhibiting eye growth

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