Effect of Radiation on Eye Health : An IVI-VisionPlus Panel Discussion

We live in a world where there is near-constant exposure to radiation from several sources, including the sun’s harmful UV radiation. Radiation affects our eyes and can cause severe long-term damage to them. Corneal damage, cataracts and macular degeneration are all possible chronic effects of radiation exposure and can ultimately lead to decreased vision and, in some cases, even blindness.

The IVI-VisionPlus Magazine panel discussion on 20 July to commemorate UV safety awareness month, featured a strong panel of experts. Shekhar Nambiar, General Manager, Education and Communications, IVI, moderated the discussion, and the panel comprised Dr GVS Murthy, Director, Indian Institute of Public Health, Hyderabad, Dr Rashima Asokan, Head of Occupational Optometry Department, Sankara Nethralaya, Chennai, and Dr Anitha Aravind, Head of Education, OCI.

The Global UV index is a yardstick developed by the World Health Organisation (WHO), the United Nations Environment Program (UNEP) and other international institutions to measure UV radiation levels globally. UV index levels of 1 or 2 are generally considered safe. On the other hand, UV index levels above 6 and 7 mean that you are at a high risk of UV radiation (UVR) exposure. India is geographically located in a region with a significant risk of exposure to UV radiation and ocular conditions where UV is a causative factor. Indians should, therefore, be aware of the dangers posed by exposure to UVR in their surroundings and make informed decisions on the level of UV protection and precaution required to protect their eyes.

However, as Dr GVS Murthy pointed out, it must also be borne in mind that there is no ‘one-to-one relationship.’ As UVR increases, it does not directly translate into an increase in particular eye conditions. This is because many factors, often called the ‘spider’s web,’ are all causative and act on ocular surfaces.

Radiation is, nonetheless, a significant causative factor affecting eye health. Studies have shown, for example, that in India’s coastal regions, there is a higher presence of pterygium compared to the landlocked plains in Haryana or Assam. This can be explained by the fact that the coastal areas are located adjoining the sea, where the refraction of radiation is far greater than in the landlocked plains. Sand, water, snow, etc., can have a debilitating effect on the eyes.

Similarly, for cataracts, as the daylight exposure to sunlight increases cumulatively over the lifespan of an individual, the risk of cataracts also increases. Studies have shown that regions closer to the equator show a higher prevalence of cataracts due to exposure to radiation than regions situated farther away. Studies in India, China, and Taiwan have shown similar results on the correlation between exposure to UVR and the prevalence of cataracts and pterygium.

Mr Nambiar drew the panelists’ attention to the widely-held belief that UV radiation only harms the skin and requested panelists to dispel the myth. “For a layperson, only sunscreen lotion usually comes to mind when UV radiation is mentioned. However, not many are aware of the adverse effects UVR may potentially have on eye health,” Dr Anitha Aravind noted, “excess exposure to UV rays can put a person at risk for, among other things, eye cancer, cataracts, sunburned eyes, and growths on or near the eye.”

Studies in developed countries have shown that while as many as 74% of parents make their children wear sunscreen, only 32% make their children wear UV-protected sunglasses. An estimated 53% mistakenly believe that sunglasses with darker lenses provide better eye protection. This is a myth. Even clear lenses can be 100% protected. One doesn’t have to go by the lens’s tint or colour. It is the level of UV protection offered that matter.

Practitioners need to do more to communicate with their patients and the general public about the harmful effects of UV radiation on eye health. For many people, UV protection is not a consideration when buying a pair of sunglasses. Many of the low-cost sunglasses available in the market are tinted and not filter lenses. A good pair of sunglasses are tinted filter lenses and filter out all the harmful radiation. Consumers should be advised to buy sunglasses that are labelled UV 400 or provide 100% UV protection.

Highlighting the value of UV-safe intraocular lenses, Mr Nambiar asked whether all intraocular lenses are UV-safe. According to Dr Rashima Asokan, most intraocular lenses are UV-safe. “Nowadays, intraocular lenses are UV-blocking lenses. Normal spectacles as such have UV-blocking properties.” A person who has been wearing spectacles since childhood would probably have more protection from UV rays than someone who has never worn a pair of spectacles.

Apart from UVR, other forms of radiation can also be potentially harmful to the eyes. “People working in certain industries such as the welding industry or radiation units also face threats, including infrared radiation. For instance, a person who looks straight at the sun for a long time may have a solar burn of the retina,” Dr Murthy observed. The threats posed by such radiation usually come in the form of occupational hazards faced by some. These non-UV rays, however, do not pose a significant risk in day-to-day life. People working in high-risk occupations need to be given protective gear that shields the eyes and the entire body from various kinds of radiation.

Radiation poses multiple challenges to eye health. Ultimately, every individual must take the necessary precautions to shield one’s eyes from UV and other forms of radiation depending on their environment, occupation and lifestyle. Simple steps such as wearing UV-blocking sunglasses when you step outdoors during the day can help shield your eyes from harmful radiation. Oversized and wrap-around sunglasses prevent radiation from seeping through the sides of the protective eyewear. These also happen to be fashionable.



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