Choroidal Thickness and Volume Modifications Induced by Aerobic Exercise in Healthy Young Adults

IMI-The Dynamic Choroid: New Insights, Challenges, and Potential Significance for Human Myopia

The choroid is the richly vascular layer of the eye located between the sclera and Bruch's membrane. Early studies in animals, as well as more recent studies in humans, have demonstrated that the choroid is a dynamic, multifunctional structure, with its thickness directly and indirectly subject to modulation by a variety of physiologic and visual stimuli. In this review, the anatomy and function of the choroid are summarized and links between the choroid, eye growth regulation, and myopia, as demonstrated in animal models, discussed. Methods for quantifying choroidal thickness in the human eye and associated challenges are described, the literature examining choroidal changes in response to various visual stimuli and refractive error-related differences are summarized, and the potential implications of the latter for myopia are considered. This review also allowed for the reexamination of the hypothesis that short-term changes in choroidal thickness induced by pharmacologic, optical, or environmental stimuli are predictive of future long-term changes in axial elongation, and the speculation that short-term choroidal thickening can be used as a biomarker of treatment efficacy for myopia control therapies, with the general conclusion that current evidence is not sufficient.

The outdoor environment affects retinal and choroidal thickness

PURPOSE

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.

Therapeutic and preventive eff ect of physical exercises in primary open-angle glaucoma

The review assesses physical exercises as an additional non-pharmacological mean of combating the progression of primary open-angle glaucoma. The ophthalmic hypotensive effect is determined by the type of exercise, its duration and intensity. Moderate aerobic activity is preferred. Among dynamic exercises, jogging has the greatest hypotensive effect. Upper body isometric resistance training provides a more lasting decrease in ophthalmotonus. The decrease in intraocular pressure (IOP) in patients with glaucoma is several times more pronounced in comparison with healthy people and occurs regardless of the nature of the local drug antihypertensive therapy. After the termination of classes IOP returns to the previous level on average within a month. An increase in ocular perfusion pressure associated with physical activity dictates the appropriateness of physical exercise for patients with pseudo-normal pressure glaucoma. The combination of hypotensive, vascular, neuroprotective effects of physical activity with a high level of physical fi tness does not exclude a decrease in the risk of development and progression of primary open-angle glaucoma. The development of indications for the use of physical activity by patients with advanced glaucoma, including those who have undergone hypotensive surgery, remains relevant. The type, intensity, dosage and mode of performing the recommended physical exercises require an individual choice.