New findings demonstrate that exposure to sunlight can reduce the increase in fundus blood flow perfusion caused by near work in an intensity- and time-dependent manner. Photo: Getty Images.

Myopia is a global concern and there is a need for proactive preventive strategies. A recent study—published in British Journal of Ophthalmology—suggests that exposure to higher illuminance sunlight can restore fundus blood flow perfusion (BFP) more rapidly compared to lower illuminance levels; however, the duration of exposure remains crucial. To help prevent myopia, the study authors recommend continuous sunlight exposure for more than 15 minutes to help reinstate the fundus BFP affected by near work.

This parallel, randomized controlled trial sought to assess the short-term effects of different sunlight exposure on fundus blood flow perfusion (BFP) after near work and included 81 students—ages seven to 15 years—with spherical equivalent refraction between −2.00D and +3.00D. The researchers randomly assigned participants to either a low-illuminance (4k lux; 40 students) or high-illuminance (10k lux; 41 students) group.

Following one hour of indoor reading, each participant had 15 minutes of sunlight exposure matching their group’s intensity. Study authors measured blood flow perfusions in the superficial retina, deep retina and choroid at four time points—pre-reading, post-reading, fifth minute and 15th-minute sunlight exposure.

Data showed that within the initial five minutes of sunlight exposure the 10k lux cohort had a tendency for decreased BFP, particularly in the choroid, while patients in the 4k lux group showed an increase. From five to fifteen minutes, the investigators observed a decrease in BFP in both patient groups.

Additionally, at the fifth minute mark, patients in the high-illuminance group exhibited a greater decrease in choroid, the study authors reported, while also noting that there was no significant difference after 15 minutes of exposure.

“Our study emphasizes that sunlight exposure can effectively counter the increase in fundus BFP due to near work,” the study authors noted in their BJO paper. “Sunlight with higher illuminance can restore fundus blood flow more rapidly than lower illuminance, but the duration of exposure remains a critical factor. To prevent myopia, continuous exposure to sunlight for 15 minutes or more is recommended to aid in reinstating the fundus blood flow increased by near work.”