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Sunglass lenses
Sun lenses reduce the amount of visible light reaching the eye and should suit the intended use. Tint, filter category, light transmission and UV protection are separate characteristics to check on the actual product.
A dark tint does not necessarily mean UV protection
A darker tint mainly means less visible light passes through the lens; UV protection depends on the stated and certified performance. Appearance alone is not enough to judge a lens. At Isolani Optical Centres, we check the origin, markings and technical properties of the selected option.
Filter categories 0 to 4
Filter categories classify sun lenses by visible light transmission, from very light category 0 to very dark category 4. The right category depends on where and how the lenses will be used. Category 4 lenses are intended for extremely bright conditions and are not suitable for driving.
Ordinary sun lenses are not designed for looking directly at the sun or an eclipse. That requires purpose-made equipment meeting the relevant requirements.
Polarised, photochromic and mirrored lenses
Polarised lenses can reduce bothersome glare from surfaces such as water and tarmac, though not in every situation. Photochromic lenses change their light absorption according to activation conditions; a mirror coating affects some of the reflected light and the lens's appearance. Each technology has its own limits and suitable uses.
Prescription sun lenses, when needed
Many sun lenses can be made to a prescription, provided the frame, curvature, lens power and chosen technology are compatible. Behavioural Centring helps keep the optical design aligned even in large or wraparound frames.
How we choose a lens
We start with how the lenses will actually be used: driving, city life, the seaside, mountains, sport or individual sensitivity to bright light. We compare light transmission, tint, colour rendering, polarisation and prescription compatibility, explaining what the lens can do without turning a technical feature into a universal promise.
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The information on this page is provided for information purposes only and relates to the optical and commercial sectors. It does not contain any medical, clinical or diagnostic content.