Photochromic lenses are made by coating plastic or formulating glass with a permanent layer of molecules that react to ultraviolet light. That coating process is fully compatible with plastic high index lenses but cannot be applied to glass high index lenses. The choice of high index glass or high index plastic is fairly dependant on the prescription being cut; certain stronger prescriptions are only available in high index glass, which disqualifies them from the photochromic coating. The 1.56/1.60/1.67/1.74 index plastic lenses can be photochromic lenses as well. However, the 1.80/1.90 index lenses can not. So, it depends on your prescription. Many prescriptions are mild enough to be cut from either standard glass/plastic or high index plastic and can be combined with a photochromic coating. Those prescriptions that require a high index material rating of 1.80 or above also require the use of glass high index material, thus are exempt from a transition coating.
Photochromic Lenses contain light-sensitive molecules that darken and lighten according to the intensity of ultraviolet light. It clears indoors, darkens outdoors, providing visual comfort without the need to change glasses. People who participate in activities that involve frequent going indoor and outdoor often find them most helpful and convenient. Photochromic lenses are available with most of plastic material except 1.74 super high index lenses.
Yes, of course. High index is also available with polarization or photochromic options. However, as I know, it your prescription is so strong, then you need 1.80 or 1.90 index lenses, then the photochromic lenses are not available for such high index lens. However, below 1.74 index lenses are available as photochrimic lenses. Hope this helpful.
Photochromic lenses change from a light to a dark tint based on the amount of sunlight or UV exposure. Silver halide is mixed with the lens material to cause this transformation. Photochromic lenses are very versatile and very popular with customers who want to carry only one pair of glasses for clear and sun. High index is most commonly available in multiple progressive and single vision designs. Aspheric and atoric designs are also becoming more readily available to the eye care provider in high index materials. High index is also available with polarization or photochromic options.
Yes, photochrimic lenses also can be high index. the higher the index the thinner and lighter the lenses will be. High index lenses are recommended for moderate to high prescriptions and for larger sized frames. It is recommended with higher index materials that anti-glare treatment be applied as higher index lenses inherently reflect more light at the surfaces than lower index lenses.