How the Sun Affects Your Eyes

You may be aware of the harmful effects of the sun on your skin, such as sunburn, premature aging and an increased risk of cancer. However, did you know that spending too much time in the sun also increases your risk of developing some short-term and long-term eye problems?

The eyes have evolved specific protective mechanisms — such as constriction of the pupil, the squinting reflex, and closure of the eyelids — that are activated by bright visible light. However, the protection they provide is limited. Ultraviolet radiation levels can still be high on cloudy days and exposure increased by strong ground reflection from water, sand, and snow. Because the eyes’ defense mechanisms don’t work with UV radiation, there is always a risk of damage, even if they are the not directly exposed to bright sunlight.

You should be aware of the damage that can occur as a result of overexposure to the sun if you want to safeguard the health of your eyes.



Photokeratitis occurs as a result of UV light penetrating the eyes and causing inflammation of the cornea. This condition, akin to a sunburn of the cornea, causes symptoms including redness, pain, swollen eyelids, watering, blurred vision, and light sensitivity that usually start 6 to 12 hours after exposure to UV light.

Although photokeratitis is a temporary condition that usually heals within a few days, it can be painful. If so, a doctor can prescribe a topical medication to ease symptoms and aid healing.



When UV light penetrates the eyes, it can cause inflammation of the conjunctiva, the thin membrane that lines the insides of the eyelids and the front surface of the eye. Symptoms, which usually occur within a few hours of exposure to UV light, include pain, redness, and a sensation of a foreign body, such as grit being in the eye.

Like photokeratitis, photo conjunctivitis is painful. A doctor can prescribe a topical treatment for the symptoms. The condition usually resolves within a few days with no long-term ill effects.



A pterygium is a growth that starts on the conjunctiva and progresses to the cornea. It typically looks like a triangular flap of tissue that extends from the inner corner of the eye near the nose towards the center of the eye and appears white with many visible blood vessels.

Symptoms of pterygium include inflammation, redness, dryness, watering, and the feeling of grit under the lid. Treatment usually depends on the size of the growth. If it extends to the center of the cornea and causes visual problems, surgery may be necessary. However, symptoms are typically manageable with non-surgical treatments such as topical steroids, anti-inflammatory agents, and artificial tears to ease dryness and irritation.

Several factors may contribute to the risk of developing pterygium, but research has shown that it often occurs after extended exposure to UV radiation.



Cataracts are cloudy patches that develop on the eye lens, which should be transparent. Symptoms include reduced, blurry, and spotty vision, worsening as cataracts grow. The condition will require surgical removal followed by insertion of an artificial replacement for the eye’s natural lens.

Cataracts are the leading cause of blindness worldwide, and, although most often associated with aging, the World Health Organization estimates that overexposure to ultraviolet radiation may account for up to 20 percent of cases.



Exposure to UV radiation increases the risk of developing skin cancer of the eyelids and eye cancer.


Eyelid cancer

As much as 5 to 10 percent of all skin cancers occur on the eyelids. These include basal cell carcinoma, squamous cell carcinoma, and melanoma.

Basal cell carcinoma is the most common type of eyelid cancer. Usually first noticed as a small patch or nodule, symptoms can also include eyelash loss and the eyelid pulling away from the eye. With early detection, basal cell carcinomas are highly treatable through surgical removal. They develop slowly and rarely metastasize, but, if left untreated, they could grow into the orbit of the eye, the sinuses, and the brain.

Squamous cell carcinoma, the second most common form of eyelid cancer, can look like a flat, flaky, or scaly patch that may be pale or reddish with many noticeable blood vessels. A tumor also could be a red, thick, scaly, wart-like growth, sometimes with crusting and bleeding that makes it look like an open sore. Treatment options include topical medications, photodynamic therapy, cryosurgery, electrosurgery, and surgical removal. When detected and treated at an early stage, squamous cell carcinomas are usually curable. Left untreated, they can become disfiguring and, in a small percentage of cases, can metastasize to other organs and be fatal.

Melanoma is the most dangerous type of skin cancer. Although, it seldom develops on the eyelids. When it does, it typically appears as a thickened, pigmented patch that may also change color, bleed, and grow. Treatment depends on whether the melanoma has spread and what stage it has reached. Initially, the surgeon will remove the tumor. If cancer has metastasized, it may require chemotherapy, radiotherapy, or biological therapy.


Eye cancer

Scientific evidence suggests that lifelong exposure to the sun may increase the risk of developing ocular cancer. Melanoma is the most common form of ocular cancer in adults, but it is rare.

Ocular melanoma may not be evident in its early stages. As it progresses, a dark spot can appear on the conjunctiva or iris, and the shape of the pupil can change. The patient may also see flashing lights and have distorted vision.

A small percentage of ocular melanomas develop in the iris. These can be slow-growing and don’t always require treatment. However, if a tumor grows or causes symptoms, surgery or radiotherapy can become necessary.

Most ocular melanomas develop in the choroid or ciliary body. Treatment depends on the tumor’s location and size and the extent to which it is affecting vision. In some cases, a surgeon can remove the growth or treat it with radiotherapy, but, if it is substantial and causes loss of vision in the affected eye, it may be necessary to remove the eye. If the melanoma spreads to other parts of the body, it may need chemotherapy or biological therapies.

Squamous cell carcinoma is also rare. It develops on the conjunctiva and can appear as a white or yellowy-pink nodule or spread across the surface of the eye. Treatments include surgical removal of the tumor as well as cryotherapy and chemotherapy eye drops. Although this type of cancer can spread to the orbit and sinuses, it rarely metastasizes to other parts of the body.

The best thing you can do to reduce your risk of developing one of these problems is to limit the amount of time you spend exposed to the sun’s UV rays. When spending time in the sun, you should always wear sunglasses with 100% UV protection, as they filter the UV rays and prevent them from penetrating your eyes.