Frequent wearing of sunglasses may be fashionable but an expert has warned that it could damage your eyesight.

It is not uncommon to see people wearing dark glasses to protect their eyes, especially during a hot day. But Nuptal Sarmah, an ophthalmologist from ASG Eye Hospital in Nakasero, Kampala, says some of the sunglasses damage human eyes since they expose those wearing them to ultra-violet rays causing muscular degeneration and other conditions which affect vision.

Sarmah explains: “Sunglasses with improper Ultra-Violet (UV) protection can be far worse than not wearing sunglasses at all. This is because your eyes are naturally created with the ability to regulate the light and protect themselves from UV light by shrinking the size of the pupils.”

Sarmah adds that creating darkness artificially by wearing sunglasses makes “the pupils open up wide and allow in even more potentially harmful UV light."

According to Sarmah, sunglasses prevent hormonal regulation. “In a normal situation, you need natural light to help regulate hormones. Sunlight that reaches your eyes stimulates the hypothalamus in the brain which is connected to the pineal gland. The pineal gland is largely responsible for regulating sleep by secreting the good sleep hormone-melatonin,” he said.

It is this process that is affected by sunglasses, as they inhibit the natural contrast of light during day and night which would otherwise help in healthy hormonal secretions and healthy sleep.

Sarmah added that the eyes may become less adoptable to light and dark as an effect of sunglasses. He reasoned that if one’s eyes are not consistently exposed to the various rays of UV light, then one’s ability to adapt to light will decline as well as their vision.

Mayobo Caroline, a second year student of Journalism and Communication, said that wearing sunglasses worsened her eyesight. "I was so addicted to wearing sunglasses until my eyes started hurting on removing them or when I looked at white objects. I then went for eye checkup during the Makerere Health Week and the results were not pleasing," Mayobo says.

Mayobo explains that the optician said the pain in her eyes was the effect of eye fatigue. This was because since her eyes were naturally designed to interact with light, her continued use of sunglasses stressed the eyes and they were forced to adjust and operate through an unnatural "tint" thus over-training her eyes was one way to end up with reading glasses.

Vicent Ssekito an optical specialist at Mengo Hospital advices that it is important to eat a wide variety of vision friendly fruits such as carrots rather than using sunglasses. This is because nutrition plays a very big role in how eyes adapt to UV exposure.

The American Academy of Ophthalmology (AAO) recommends polarized lenses which don't block UV rays but cut down on the glare for better visibility. AAO adds that the glasses have to be labeled with a sticker that says that they block up to 95% to 100% UV rays or claims to be "UV absorption up to 400nm" which means 100% blockage.