By Denis Langlois

April 22 marks the 51st annual Earth Day.

Recognized as the largest secular observance on the planet, Earth Day is an annual event aimed at demonstrating support for environmental protection.

Each year on Earth Day, people around the globe take part in activities to better the environment and planet, such as picking up litter, planting trees, making a pledge to reduce their plastic use, starting vegetable gardens or holding educational events on the impacts of climate change and global warming.

Many optical companies have become leaders in adopting ways to reduce their carbon footprints year-round and have designed more sustainable, environmentally friendly eyewear.

One of the main ways they’re doing so is by developing frames that include bio-based materials, created from such renewables as grass fibers or castor bean oil – which is durable and lightweight – or recycled content, like old fishing nets or recovered ocean plastic.

Some companies are also using packaging, promotional and other materials from recycled or renewable materials, like cotton.

A few companies have gone even further and have committed to planting a tree for each frame sold or have revolutionized their manufacturing processes to make them more environmentally friendly.

Here are some optical frames and sunglasses that feature eco-friendly materials.