# Optical Forums > General Optics and Eyecare Discussion Forum >  Question on Essilor Crizal Alizé

## breeze

Hello to everyone,
 I am writing to you because I have a doubt concerning my new lenses Essilor Fusio 1.74 with the Crizal Alizé coating.

I have read that the residual color of the coating should be green. 

First. It is usually green but in some cases it is white and the reflexes are quite annoying.

Second. The reflexes of neon lights are green with zones of purple. Basically the two lenses have spots of purple, such spots are not located in the same way in the two lenses.

I am experiencing a bad night vision with such lenses and I think it is the AR coating which is defective. I returned the lenses but Essilor lab said they are ok. But I am in Italy and warranty is an opinion here.

My question is:
- why do I see purple reflexes when other glasses (I do not know their AR coating) have a uniform reflex under the same neon lights?

In few months I will change the lenses. Do you know any manufacturer producing lenses with an AR with a blue residual color?

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## QDO1

It is usual for the reflex colour to vary depending on the angle you are looking at it.  Hoya coatings are generally blue(ish)

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## breeze

> It is usual for the reflex colour to vary depending on the angle you are looking at it.


Thanks for the answer.
The problem is that it does not vary depending on the angle: the purple areas remain purple even when moving the glasses.

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## QDO1

> Thanks for the answer.
> The problem is that it does not vary depending on the angle: the purple areas remain purple even when moving the glasses.


one would expect the lens coating to be homogenious - the same all over.  It isn't unusual to see 2 or three colours in the reflex, but that would be consistant across the entire lens surface, and between the pair of lenses

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## Chris Ryser

Your residual color has been applied by the coating lab and is made with different metal oxydes that give it the hue, depending which oxyde is used it will have another color.

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## coda

You have a high index lens, you're probably seeing the effect of a mismatch between the refractive index of the hard coating and the lens material.  This would explain why the zone of 'off color' is in a fixed position.  From a visual performance standpoint this is not a significant defect in either lens or coating.  Obviously you're not happy with the cosmetics.  I doubt that either the AR or hard coat fringe (term of art in the lens industry) are causing your difficult night vision.  My first guess would be off power in the lens, you're aware of this at night because humans have poor night vision so any slight off power in the lens becomes more significant at night.  My final thought is that you should ensure that you're lenses are clean.

Zeiss-SOLA makes a lens coating in the US called Teflon, it has a nice blue color and excellent performance.

Good luck.

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## breeze

> Obviously you're not happy with the cosmetics.


May be that's why Essilor lenses are cheaper than Zeiss or Seiko lenses (at least in Italy). You can find Essilor Fusio 1.74 with Crizal Alize' at 100 euro each, but you cannot find a 1.74 Zeiss lens for less than 200 euro each (in Italy).




> I doubt that either the AR or hard coat fringe (term of art in the lens industry) are causing your difficult night vision. My first guess would be off power in the lens, you're aware of this at night because humans have poor night vision so any slight off power in the lens becomes more significant at night. My final thought is that you should ensure that you're lenses are clean.


The correction is the same as previous lenses which were very high index GLASS lenses (with blue/purple AR). I asked to check the actual correction and it is ok. Do you think that the problems might be caused by the plastic material of the new lenses?

I think, but it is a conjecture, that the main problems are
1. the geometry. The new lenses are aspheric and there is often a huge reflex on one of the two sides. Reflexes on the previous lenses are much smaller.
2. the residual color. On the new lenses the reflexes are usually green but with some colors they are white. I think the blue/purple reflexes of the previous lenses were easier to tolerate.

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## QDO1

> May be that's why Essilor lenses are cheaper than Zeiss or Seiko lenses (at least in Italy). You can find Essilor Fusio 1.74 with Crizal Alize' at 100 euro each, but you cannot find a 1.74 Zeiss lens for less than 200 euro each (in Italy).
> 
> 
> 
> The correction is the same as previous lenses which were very high index GLASS lenses (with blue/purple AR). I asked to check the actual correction and it is ok. Do you think that the problems might be caused by the plastic material of the new lenses?
> 
> I think, but it is a conjecture, that the main problems are
> 1. the geometry. The new lenses are aspheric and there is often a huge reflex on one of the two sides. Reflexes on the previous lenses are much smaller.
> 2. the residual color. On the new lenses the reflexes are usually green but with some colors they are white. I think the blue/purple reflexes of the previous lenses were easier to tolerate.


UK pricing is similar to Italy in proportion.  Fitting of the lens might be a really big issue, look at front angle, dihedral and vertex, all of these will make a big difference to reflex'es

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