Only Some Contact Lenses Protect Against UV Radiation

sunglasses-uv

Even high quality sunglasses can let in as much as 50% of the surrounding radiation to the eye.

Studies have shown that UV radiation from the sun and solariums can be harmful to the skin. The harmful nature of ultraviolet radiation is not, however, limited to the skin but can also affect other parts of the body: the eyes are also in danger1. It is important to protect not only your skin from the sun’s UV radiation but also your eyes.

Exposure to UV radiation causes gradual damage to the eyes and as people get older this can lead to many problems such as cataracts or other eye diseases that require surgery2. The danger increases especially for those over the age of 40. In the worst instance, the eyes can be permanently damaged by sunshine and this could lead to blindness.

It is extremely important to protect the eyes when close to water because of reflections.

It is surprising but even if you wear sunglasses as much as 50% of the surrounding UV radiation can reach the eyes3, in which case contact lenses that block ultraviolet radiation offer welcome added protection. However, only a small number of contact lenses are UV protected, and the majority of consumers do not necessarily know whether their own lenses have UV protection or not.

Sunglasses and contact lenses together provide the best protection. Large sunglasses that cover the eye worn together with contact lenses that have UV protection can effectively reduce the amount of radiation entering the eye.

 

Radiation from the side of sunglasses

The UV Index, which ranges from 0–20, describes the strength of ultraviolet radiation. In New Zealand the index varies greatly and in the north of the country can reach as high as 13, while be as low as one in the south during the winter. In popular tourist destinations such as Thailand, however, the figure may be as high as 15.

Sunglasses do provide protection for the eyes but most of them do not block all UV rays by any means. The lenses of well-made sunglasses do block UV radiation from around the lens itself but the amount of radiation entering the eye from above, below and the sides of the lenses is surprisingly large. According to research, some sunglasses only prevent about 50% of the UV radiation from reaching the eye. Complete protection is only afforded by using glasses that tightly surround the eye, such as for example goggles for swimming or skiing.4,5

The UV protection from sunglasses can be improved with contact lenses. Some contact lenses promise to block as much as 96% UVA radiation and 100% of UVB radiation. Most lenses do not, however, have separate UV protection. The choice of material is important because contact lenses with class I UV protection (e.g. senofilcon A) give significantly better eye protection than lenses made from materials that allow UV radiation to penetrate (e.g. lotrafilcon A).6

Acuvue brand lenses seem to offer the best protection at the moment. The difference is considerable compared to untreated lenses which may block only 10% of UVA radiation and 30% of UVB radiation.

Since contact lenses do not cover the entire cornea, they cannot by themselves protect the eyes. Using only lenses that have ultraviolet protection provides a smaller benefit against harmful radiation than sunglasses. For the eyes get the best possible protection, doctors recommend that sunglasses and protective contact lenses are used at the same time.

The UV protection afforded by contact lenses varies significantly.

 

1 Chandler H. Ultraviolet absorption by contact lenses and the significance on the ocular anterior segment. Eye Contact Lens. 2011 Jul;37(4):259-66. Review.

2 Roberts JE. Ultraviolet radiation as a risk factor for cataract and macular degeneration. Eye Contact Lens. 2011 Jul;37(4):246-9. Review.

3 Rosenthal FS, Bakalian AE, Lou CQ, Taylor HR. The effect of sunglasses on ocular exposure to ultraviolet radiation. Am J Pub Health. 1988; 78:72-74.

4 Sliney DH. Photoprotection of the eye: UV radiation and sunglasses. J Photochem Photobiol. 2001; 64:166–175.

5 Coroneo MT, Müller-Stolzenberg NW, Ho A. Peripheral light focusing by the anterior eye and the ophthalmohelioses. Ophthalmic Surg. 1991; 22:705–711.

6 Chandler HL, Reuter KS, Sinnott LT, Nichols JJ. Prevention of UV-induced damage to the anterior segment using class I UV-absorbing hydrogel contact lenses. Invest Ophthalmol Vis Sci. 2010 Jan;51(1):172-8.

2017-09-20T02:28:33+00:00 Eye Health, News & Innovations|