Life on Earth cannot exist without sunlight. The ultraviolet radiation in sunlight has beneficial effects on human health, such as promoting the synthesis of vitamin D.
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Excessive sun exposure can have negative effects on the skin, eyes, and immune system (Photo: boattest) |
However, too much sun exposure can adversely affect the skin, eyes, and immune system. The harmful effects of sunlight on health are due to ultraviolet rays present in sunlight, which include the three types: UV-A, UV-B, and UV-C.
How does sunlight affect the eyes?
The eyes can be affected immediately or over time after absorbing ultraviolet rays from sunlight. Many parts of the eye are affected by ultraviolet rays, including the eyelids, conjunctiva (the white part of the eye), cornea (the black part at the front), lens (the eye’s lens), and retina (the part inside the eye that functions like film to capture the images we see).
In the eyelids, sunlight can cause various types of eyelid tumors, particularly eyelid cancers such as basal cell carcinoma, squamous cell carcinoma, and malignant melanoma.
For the conjunctiva and cornea, exposure to intense ultraviolet rays can cause corneal burns, with symptoms such as irritation, discomfort, redness, glare, tearing, and this condition often improves within 48 hours. Long-term exposure to ultraviolet rays may lead to pterygium or “pinguecula” on the conjunctiva. Gradually, pterygium grows onto the cornea, affecting vision. “Pinguecula” refers to small yellowish patches on the conjunctiva that usually do not affect vision.
Cataracts can arise from various factors and are commonly seen in older individuals, leading to blindness, especially in countries lacking access to cataract surgery and artificial lenses. There are three basic types of cataracts: cortical, nuclear, and posterior subcapsular. Numerous epidemiological studies have shown that prolonged exposure to sunlight gradually leads to cortical cataracts.
Looking directly at the sun for extended periods, especially around midday, can cause retinal burns (sun-related retinopathy). This condition is also commonly seen after watching a solar eclipse without protective eyewear. Additionally, age-related macular degeneration, a leading cause of blindness in developed countries, is believed to be associated with prolonged exposure to sunlight (the macula is located at the center of the retina and is responsible for our ability to see colors and detail).
How to protect your eyes from the harmful effects of sunlight?
The most important measure to avoid the harmful effects of sunlight on the eyes is to avoid direct exposure, especially from 11 AM to 4 PM, when ultraviolet rays are most intense. Therefore, for some professions that require working outdoors, it is advisable to schedule tasks to be completed before 11 AM and after 4 PM.
When it is necessary to work in the sun, create shade by using tents, umbrellas, or working under shade. Additionally, when engaging in activities directly under sunlight, it is important to use sun protection measures such as wearing wide-brimmed hats, sunglasses that absorb ultraviolet rays, and face coverings.
ThS. BS. HOÀNG ANH TUẤN (Central Eye Hospital)
