Frequently Asked Questions

If you are unable to find the answer to your question,
e-mail us your question at e-mail@x-celoptical.com
Our staff is available M-F 8 to 5:30 central time.

What are photochromic lenses?
Photochromic lenses are optical lenses that darken when exposed to ultraviolet rays. When the ultraviolet light is removed the lenses automatically lighten.

 

Who should be recommended to wear photochromic lenses?
Anyone who wears lenses who wears regular lenses because they are as clear as regular lenses indoors and adjust to any light in any condition.
 

Do photochromic lenses protect against UV rays?
Yes. When photochromic lenses are clear or dark they provide 100% protection from both UVA and UVB rays.

Can photochromic lenses be worn while playing sports?
Yes. These lenses can be worn any place for any activity, especially outdoor activities because they are 100% UV protected. The Aris Trivex lenses offer a superior shock and impact resistance and is very lightweight.

Can photochromic lenses replace regular lenses?

Yes. Most photochromic lenses are as clear as regular lenses indoors so they can be meant for everyday all the time lenses. In recent studies, four out of five eyeglass wearers prefer photochromic to regular lenses.

Can photochromic lenses replace sunglass lenses?
Photochromic lenses get dark outside but are not meant to replace a sunglass lens. Some studies show that photochromic lens wearers are more likely to own sunglasses as a second pair of glasses because when being worn behind a windshield, the level of activation is not as high because most windshields block UV rays. Sunglasses are a specialty product for specific reason. Photochromic lenses are worn for patients to see comfortably in any light.

Can I get a photochromic lens that is polarized?
Yes! X-Cel offers 3 colors in photochromic glass polarized colors of Gray, Brown and our Autumn Gold. These lenses are a medium color so as to allow the wearer good vision in a vehicle for reading dash boards ect. while changing to a full sunglass shade in the sun. Since they are polarized they are an excellent choice for driving, water and all outdoor activities eliminating most glare.

How long do photochromic lenses last?
Transitions lenses last as long as your prescription and usually out last the lifetime of a patient’s prescription which typically is 2 to 3 years. Glass photochromic unlike plastic photochromics never breakdown and work better with time.

How does AR coating affect a photochromic lens?
All photochromic lenses are compatible with AR and hard coat treatments. AR coating will improve light transmission, much like regular lenses, photochromic lenses with AR coating also add additional comfort for night driving.

Can Transition lenses be tinted?
Transition lenses are no different than any other lenses. Tinting will not affect the performance of the lens but may change the final color since Transitions do change color when in different lighting.
 

Can I still get Transitions XTRActive Lenses?
No, however Transitions from X-Cel Optical are tintable in both the 1.50 index, 1.55 High-X and our Aris Trivex materials. Follow standard tinting procedures for each material and don't over tint as to make the lens to dark when the photochromic are fully activated.

Can I get a 10 base laminated glass lens from X-Cel?
No, we can only laminate Plano through 8.25 base lens styles in the 71mm diameter size.
 

Can I get a glass slab off on a Trifocal with the slab line on the bifocal line?
Yes, however the intermediate will not look the same. The prism is ground on the front surface and as it is brought down to the lower bifocal line it removes the outer edges rounding the intermediate. The higher the amount of slab off prism, the rounder the intermediate will be.
 

Can I get a lens for someone who is welding for their safety glasses?
No. Years ago there was a Green Didymium in shades 4&5 that was intended for gas welding, gas cutting and torch brazing made by Schott Glass Technology. These are no longer made and the glass has been used. The only protection available is the welding helmets and goggles provided from welding supply companies.
 

Are Thin and Dark lenses thinner because they are a high index lens?
No, these lenses have a 1.523 index however they are 5% lighter in density than PGX and regular glass lens materials. The lenses are a patented glass material from Corning allowing them to be ground to a 1.5mm center thickness, giving you a lens that is up to 30% lighter and thinner than standard glass.
 

I thought the FDA requires 2.0 CT on glass lenses, how can these be ground thinner?
Neither FDA nor ANSI requires a minimum thickness. The requirement is that chemically tempered and heat tempered lenses must pass the FDA drop ball test for dress eyewear.
 

Can any prescription be made in Thin and Dark?
Thin and Dark lenses are available in a wide variety of lens designs and Rx’s, including single vision, bifocals, trifocals and progressives. We have also recently introduced plus powers in Thin and Dark. They can be used for Rx’s up to 5.5mm center thickness.

Why can’t these lenses be made in an hour?
This special formula of glass should be chemically tempered in the 4 or 16 hour process. Air tempering is not recommended.
 

Why is Thin and Dark darker than PGX?
These lenses have more photochromatic micro-crystals per cc. This increased crystal density makes Thin and Dark lenses turn darker.

Will Thin and Dark get dark even on hot days?
Yes. Some photochromics don’t but this lens will achieve 21% transmittance at 90 degrees F, far exceeding the performance of most other photochromatic materials on the market.
 

Will Thin and Dark darken behind a car windshields?
Thin and Dark lenses will darken behind a car windshield because they are activated by UV radiation and visible light however don't they will only achieve a light shade of grey. No photochromic lens on its own will become more than a light shade behind a windshield.  For a lens that goes from a medium to dark shade consider the polarized photochromic lenses.
 

How would you handle replacement of a single photochromic lens?
If you are replacing a plastic single photochromic lens, it is not recommended after a few months because the new lens will get darker than one that has been worn. A glass lens would need to be re-chemically treated to take the photochromics back to the original state so as to match the new lens.
 

Is Thin and Dark available in other colors?
No, brown was available but now is discontinued.
 

How much darker and lighter does Thin and Dark get compared to PGX and Transitions?
Thin and Dark transmits 86% light indoors and 16% outdoors. PGX transmits 85% indoors and 22% outdoors. Transitions transmits 89% indoors and 15% outdoors at 72 degrees F. The Transitions lens will be considerably lighter outdoors at higher temperatures.
 

How much lighter in weight is Thin and Dark than PGX and how much heavier than a standard plastic lens?
Thin and Dark lenses can be up to 30% lighter than PGX. The difference in weight between single Thin and Dark lens and standard plastic lens with a –2.00d Rx and a 50-eye size is equal to about the weight of a dime.
 

Does Thin and Dark have a green hue like PGX?
No, Thin and Dark lenses are clear indoors. PGX and PBX have slight indoor colors, while 1.6 index photochromic glass has a noticeable indoor color.
 

If you put photochromic lenses in the freezer will it go back to it’s original color quicker?
No, putting lenses in the freezer has no effect on the lenses once they are removed and reach room temperature.

What is the difference in Freedom 5 & Freedom ID?
The Freedom 5 design is intended for larger frames fitting at 22mm high. The Freedom ID is created using the latest technologies for people with active life styles and fitting into the smaller frames of today, while still providing outstanding patient adaptation, acceptance and easy fitting as low as 17mm
 

Are you 1.67 lenses aspheric or non-aspheric?
The Finished Single Vision are aspheric, the SFSV and D-28’s are not.
 

Is there an edge on our flat top 28 PBN lenses?
On most polarized plastic and poly lenses there is a small portion of the outer diameter that is not usable; this is from the manufacturing process. The diameter listed for X-Cel’s polarized lenses is the usable size of the lens. So the answer is yes, but the size listed is without that un-usable portion.
 

Do we have finished glass and plastic lenses?
X-Cel does not stock any finished glass or plastic lenses. We do stock Trivex, 1.67 and Poly finished single vision lenses at competitive prices. The reason for this is glass and plastic FSV are available from most other suppliers at lower prices than X-Cel could provide. We also have not seen much interest from our customers for those two products.
 

Are the multifocal in glass fixed tints clear segs?
Only the Grey 1, 2 & 3 D-25 and D-28 have colored segments. All other colors and styles have clear segments including all photochromics which have always been clear.

What lenses do we have that can be used for welding?
In the past there was a Green Didymium #4 & 5 available, but these are no longer available. ANZI standards are very clear on what welding shades are required for all types of welding and no glass is available to meet these requirements. For these occupations welding helmets and goggles must be worn over the patient’s safety eyewear.

Are plastic occupational double segs hard coated? And what is the separation?
Yes, all plastic standard thickness occupational lenses from X-Cel are hard coated. For both the DD-28 and DD-35 the separation is 14mm, 7mm down and 7 mm up.

In a 1.70 flat top 28 lens what would cause the seg to be foggy or hazey?
All flat top segments in glass are made from a high index glass piece, which is higher in index than the major portion of the lens and is “Fused” into the blank. As glass becomes higher in index it becomes more sensitive to chemical attack. Liquids, vapors and liquids which are high in PH including the salt baths used to chemically strengthen the lens can “Etch” the segment glass making it appear hazy. These can some times be polished to remove the hase.

 

Are Ribbon Bifocals still available?
Yes, X-Cel still supplies these to all of our wholesale lab customers.
 

Do we have thick Transition lenses and do you think we might ever get them?
X-Cel did in the past have “Thick Transitions” lenses in a SFSV and D-28 in the Quantum Grey 1.55 lens line. But due to extremely high costs due to low yields both X-Cel and Transitions decided to have this lens discontinued.