High index options for > +10 prescription

**maximum01** · 02-01-2005, 05:07 AM

Hi, I wonder if you can help. I'm currently wearing 1.67 index lenses, which look ok but I wanted to get them thinner. However, I've been given a new prescription that is slightly higher bringing my right eye +0.5 over 10 D:

R +9.00 +1.50 L +8.00 + 1.50

I've now been informed that the highest index available for me is only 1.60. That's a little depressing as I was hoping to try the neewer 1.74 index lenses. Any advice would be appreciated on how I can get the best looking spectacles with this rx.

Cheers, Charles

**chip anderson** · 02-01-2005, 07:00 AM

Index isn't the only way to get thinner. There is also smaller. Get the smallest frame you can wear, preferably with your eyes as well centered as possible in the frame. It will make a lot more difference than the material.

And for those who expect me to say it, yes contact lenses would be the best answer for you, both visualy and cosmeticly.

Chip

**maximum01** · 02-01-2005, 07:16 AM

I do wear contacts, but have been told to curb my wear-time somewhat. I therefore use spectacles at home and when driving to work. Ideally I'd like a pair of spectacles I'd be comfortable wearing out and about.

I've already been informed that small circular frames will help. Does anyone know of any high index lenses that will reach my prescription? It's frustrating that my current lenses are 1.67 index but my nmew prescription can't be made in this material.

Surely a 1.74 index lens would benefit high prescriptions over moderate ones. it therefore seems silly that these lenses are not available in my Rx.

**chip anderson** · 02-01-2005, 09:38 AM

There's always Glass, it will be thin but will weigh a ton in this Rx.

**maximum01** · 02-01-2005, 09:47 AM

Thanks. Could you please tell me what brand of glass lenses and at what index are available for me. I'd really appreciate it.

**shanbaum** · 02-01-2005, 10:23 AM

A company named "Tokai" produces 1.70 plastic lenses in an aspheric design in curves sufficiently steep to fabricate your Rx.

You might check with SpecSavers - a Google search brought them up.

**rinselberg** · 02-01-2005, 10:37 AM

Tokai Optical has an English language web site.

http://www.tokai.com

**Robert Martellaro** · 02-01-2005, 01:13 PM

Charles,

Another choice (there are very few indeed) if the Tokai lens doesn't work out would be a 5 drop (anyone remember the welsh 4 drop) cr39 lens from Bristol. Comes in a 10, 12, and +14.00 base curve. Probably use the +12 base here. They also make a less aspheric lens with a +12.00 base. Both lenses are full field.

**maximum01** · 02-01-2005, 04:13 PM

I can't find any literature that defines the power ranges for the Tokai 1.7 plastic lens. Anyone have a link?

About the glass suggestion. I've done some surfing and it seems high index glass is only available for myopes. Is this true?

Robert, thanks for the suggestion. Is this type of lens high index?

**shanbaum** · 02-01-2005, 04:17 PM

Originally Posted by maximum01

Is this type of lens high index?

Yes, the index is 1.70.

There may not be a published power range that you can view on the Internet, but I can tell you that they claim to make this product in base curves that would be suitable for your Rx - they are in our database.

**Robert Martellaro** · 02-01-2005, 05:33 PM

Charles,

This can get confusing because "Shanbaum" is a Robert also. And if he says the Tokai 1.7 can be fabriacated in your Rx you can take that to he bank.

Here's the Tokai link again http://www.tokai.com/news_events.html

Glass is available from Vision Ease with a +10.25 base in a 1.8 index. Can't say if your Rx will work with this lens without knowing the "true curve" and other factors. But like Chip said it would be extremely heavy.

Robert, thanks for the suggestion. Is this type of lens high index?

If this was directed to me (the other Robert) then no, Bristol is cr39 plastic. If your optician can get the Tokai lens then that's the lens I would recommend.

**shanbaum** · 02-01-2005, 05:37 PM

Originally Posted by Robert Martellaro

This can get confusing because "Shanbaum" is a Robert also.

Now I get it.

**maximum01** · 02-01-2005, 06:22 PM

Guys, this is great information. Thanks allot, I finally have some hope of getting back into high-index material after my 'slight' prescription change. You've no idea how much leg-work I've done phoning opticians and being told totally conflicting facts.

Obviously the plastic lens will be my first choice, and to that end I've contacted Specsavers who are looking into it.

I have one further question. Failing the Tokai lens, how thin would the 1.8 glass be compared to a high-index aspheric plastic lens? I recall speaking with an optician recently who claimed high-index glass, even at 1.9, will produce a thicker lens for extreme hyperopes due to the lack of asphericity, and the fact that the galss can't be polished to a knife-edge. Is this true?

**maximum01** · 02-02-2005, 05:50 AM

Alas, it seems again my hopes are dashed. Sepcsavers contacted their labs and, as I suspected, the Tokai 1.70 has a cut-off at +10D (base + cylinder). She also enquired about other materials, including glass, but no luck. Is seems every high-index option stops at +10.

If anyone can provide me with definate information for getting high index lenses I'd appreciate it.

**DocInChina** · 02-02-2005, 07:05 AM

maximum01

I will contact some factories about your prescription and see what options they can offer you here. Will you be using your current pair of eyeglasses again? If so, please make sure your doctor took into account the vertex distance of your current (or new) eyewear when s/he wrote the prescription. The prescription might need to be modified to account for how the old (or new) eyeglasses position on your face in relation to your eye.

Doc

**maximum01** · 02-02-2005, 08:01 AM

Thank you very much, I'd appreciate any help/info you can provide, although I must say I'm beginning to loose hope of finding a solution.

To answer your question: Yes, I still use my existing spectacles, although vision is not great. If you can find me a good high-index lens I can get the frame measurement details from my optician.

**ikon44** · 02-02-2005, 02:26 PM

you dont say what contacts you use, if they are only standard monthly\daily
you could consider another option, ciba night and day lenses will give your eyes
much more oxygen and should be ok for all day wear, you would only need top up glasses as they only go up to +6.00. but you could get a very thin pair of lenses as 1.67 or 1.74 are available in +4.50/+5.00.. i have used this option on a
client with a +12.00 prescription with great results .. good luck

**chip anderson** · 02-02-2005, 02:43 PM

Robert:

Don't think Ciba Night & Day is available in this much plus., I think +6.00 is max.

**maximum01** · 02-02-2005, 02:54 PM

My contact lenses are fine. I use RGPs. Vision is good, but I've been advised to keep wear time to 12 hours. The spectacles are for getting to work and in the evenings to give my eyes a rest.

I'm simply interested in finding nice thin lenses for my high prescription.

So my question remains: does there exist a lens available in my Rx with an index > 1.60.

**Robert Martellaro** · 02-02-2005, 03:33 PM

Originally Posted by maximum01

I recall speaking with an optician recently who claimed high-index glass, even at 1.9, will produce a thicker lens for extreme hyperopes due to the lack of asphericity, and the fact that the glass can't be polished to a knife-edge. Is this true?

Essentially true.

The first obstacle with this type of Rx is to find a lens with a base curve (front curve) that is steep enough to keep the ocular curve (back of the lens) from becoming convex. You will not be satisfied with the vision if the lens is bi-convex. It would be nice to have some curve on the back, even as little as -.50 or -1.00 would be desirable. Although Tokai's web sight shows plus to only +10.00, +10.50 might be doable. Robert thinks so (the other Robert) so I would have your optician consult with their lab and have the lab determine if this can be done. Seiko's 1.67 also goes up to +10.00 and is worth a look.

Hope this helps

**maximum01** · 02-02-2005, 04:41 PM

How could a +10.50 could be doable when the maximum base curve is 10.0D? As I understand it, something like a +11.5 -2.00 would be possible because the overall power is only 9.50. I called the labs at Essilor and that's what I was told.

Every single optician I speak to initially claims "yes, that will be possible", only to contact the lab and be told the cut-off is +10.0 (base + cylinder).

Does anyone have "definate" information on who/where I can get high-index lenses in this prescription? I'm at the stage where I don't want to know if it is "possible", but who can actually do it.

**Robert Martellaro** · 02-02-2005, 05:57 PM

How could a +10.50 could be doable when the maximum base curve is 10.0D? As I understand it, something like a +11.5 -2.00 would be possible because the overall power is only 9.50. I called the labs at Essilor and that's what I was told.

The higher index of refraction makes it possible to use slightly flatter curve to achieve the same degree of focusing power. You need to know the true curve and whether it's referenced to crown glass or 1.7 index. Ignoring thickness, a +10.00BC glass lens with a plano or flat back curve would provide about ten diopters of refractive power, and a 1.70 index lens might provide about 10.75 diopters of power.

Every single optician I speak to initially claims "yes, that will be possible", only to contact the lab and be told the cut-off is +10.0 (base + cylinder).

The lab needs to enter the information provided by the lens manufacturer, along with the Rx, into their surfacing computer to know if this can be done or not. If it can't be done, another possibility would be to cut the power to +10.00 and fit the glasses an extra two millimeters from the eyes. That will bring the power to +10.25, and who knows, the doctors vertex might be 10mm and the frame might sit 14mm from the eyes effectively creating +10.50 of power. Investigate the feasibility of wearing an Rx with .50 less power, it might be ok for social occasions, daytime driving etc. Then have another pair made "by the book" for more visually demanding tasks.

Does anyone have "definate" information on who/where I can get high-index lenses in this prescription? I'm at the stage where I don't want to know if it is "possible", but who can actually do it.

Maybe Robert can run this through his computer since he has the manufactuers specs. I'am also curious if this can be done for future reference.

**Jerry Thornhill** · 02-02-2005, 11:30 PM

It can be done on Seko 1.67 providing that the frame is not too large. I have done total plus of 11.25 on these lenses. They have or did have an 11.25 Base.

Jerry

**maximum01** · 02-03-2005, 02:39 AM

Thanks, I'll contact the lab about it. How did the 11.25 turn out in this lens material?

**DocInChina** · 02-03-2005, 11:22 PM

maximum01

The following is available in your prescription as per the factories I spoke to:

1.70 glass in a 200 base curve

1.74 plastic

The 1.74 would have to be ordered from Japan and the 1.70 can be ordered from Taiwan. If this is something you want, have your optician or doctors office that will be making the glasses for you contact me and I can discuss with them how to proceed.

Doc