Welcome to question of the day #80

Welcome to question of the day #80

Why is blue light and UV so damaging to the eye?

The short answer is because they both consist of short wavelengths. Solar and human made energy with short wavelengths is far more damaging to human tissue than energy with long wavelengths.

Blue light is part of the visible spectrum and has the shortest wavelength of the entire spectrum. Ultraviolet (UV) light is even shorter in wavelength than blue light but is not visible. The key point here is that the energy of the radiation is inversely proportional to the wavelength. This means that radiation with short wavelengths has much more energy than radiation with long wavelengths and it is this energy that causes tissue damage.

Some forms of UV do not damage cells directly but can generate highly reactive chemicals, which in turn can damage cells. UV radiation at even shorter wavelengths causes damage at the molecular level to the fundamental building block of life: deoxyribonucleic acid (DNA). It absorbs UV and this changes the shape of the molecule via disruption to hydrogen bonds, formation of protein-DNA aggregates and strand breaks. Distorted proteins are created and cells die.

Themolecular effects of blue light and UV can be carcinogenic (cancer causing) and have a whole range of effects on the eye:

Basal cell carcinoma of the eyelids

Squamous cell carcinomas of the conjunctiva

Pterygium

Pingeculae

Cataract

Choroidal melanoma

Age-related macular degeneration

Stay out of the sun and if you can’t then wear a decent pair of sunglasses