Chuckles: A Fable

Chuckles the Chocolate Lab knows that the sun's UV (ultraviolet) radiation has been linked to:

1.  Cataracts, a clouding of the eye's lens, eventually necessitating surgical removal,
2.  Cancer in the delicate skin around the eyes (melanoma),
3.  Macular degeneration (according to some studies), resulting in loss of vision in the center of the visual field,
... and several other types of eye damage.

So Chuckles doesn't leave home without his sunglasses, especially in the summer.  When he purchased them, he made sure the lenses block 100% UVA/UVB.  He was savvy enough to decline sunglasses with plastic lenses, even though they were tinted very dark; he knows it's the glass and polycarbonate lenses that protect his eyes.  Furthermore, Chuckles was careful to select a pair with large, close-fitting lenses—and not just because they're fashionable.  He realizes UV radiation poses a hazard to his eyes.

Chuckles knows it's no laughing matter.

(This thinly-veiled admonition brought to you by your friendly virtual optician.)