Eye Protection
Home Up

 

So what eye protection is appropriate?  To date, the only person I've found that was willing to come out and make statements about what was appropriate is Dr. Robert Hammer, an optometrist in Israel.  I've appended his statement (taken from a post I got off the MD Support mailing list) to the bottom of this page (click here)  I showed this to my Ophthalmologist, and he wouldn't commit one way or the other.  However, if you look at Dr. Hammer's recommendations, they make a lot of sense. 

So, with that in mind, I set off to research sunglasses.  Dr. Hammer was recommending something that would block as much light as possible below 600 nm in wavelength.  What I found is that this was no simple task.  Many manufacturers can and will tell you the light transmission characteristics of the lenses they sell, few can do so at specific light wavelengths.  To complicate matters further, the right lens, in the wrong frame is of little value.  Specifically, the glasses need to be either of a wrap around type or have side shades to protect the eye from light coming from the sides.  Light should not be able to enter into the eye from over the top of the lens either.  And ideally, it would be blocked at the bottom. 

In actual practice, few lenses are made in this matter.  The ones that are tend to be of the "blade" type worn by bicycle racers, and other sports enthusiasts.   These type lenses sometimes do not stand up well to continuous wear and the on/off of daily life.  Those that will, are considerably more expensive (hey, as far as I was concerned, money wasn't an object here.  I was willing to pay whatever I needed to to get what I needed.).  With these factors in mind, I went looking.

Three types/manufacturers were checked.  I zeroed in on these three because I had either heard good things about them from other macular degeneration patients or because I'd seen information about them on one of the Macular Degeneration Sites.

I checked the NoIR product line, but they didn't have the specific wavelength transmission information on their web site, and my note to them asking for more information has gone unanswered.  They do have wrap around models of of their "shields", but they are bulky in nature and resemble safety goggles.  I'm not sure, but you can probably wear regular glasses under them.  The products that they have in a more traditional frame do not have wrap around lenses.

I also looked at the melanin lenses.  These would probably be the overall best choice IF they were available in the correct format (i.e. wrap around).  Again, they aren't.  The company web site is here, but be warned that the web site has a lot of broken links. 

The lenses I ended up buying are made by Oakley.  Oakley actually does have a transmission graph for each of their lenses.  They include a copy with each pair of glasses sold.  I've scanned this graph, and posted it here.   I didn't get specific permission to do this, and I'm hoping they don't make me take it down.  These graphs aren't on their web site.  If you scroll to the bottom of the graph, those are the lenses that I was even willing to consider.  Due to the high protection factor (not to mention some of the exotic materials they use to make them), most of these really dark lenses are only available in their high end product line.  I ended up selecting the 24k Iridium lenses because they appeared to be the best protection against wavelengths below 600nm.  You can see the ones I ended up with on Oakley's site here .  The ones I got are the ones they call the 24k frame with the 24k Iridium lenses (shown in the upper left corner of the window).  They weren't cheap, and I think they are among the most expensive ones Oakley makes.  They come in at a retail price of $325 US.  Checking around got me the additional information that Oakley tightly controls their dealer network as far as pricing is concerned.  You may find Oakley at higher prices, but I couldn't find them at lower prices than on the on line web site.  Most places were the same. 

I got mine at a local shop that specializes in Oakley products.  The fit felt really strange, and I was worried that I might not be able to get used to them.   However, that worry proved to be groundless as after two days, I found them to be the most comfortable frames I've ever had.  I wear them pretty much all the time, both indoors and out.  This causes a little eyebrow raising from folks that don't know me, but quite frankly, I really don't care.  This is about long term vision, not trying to be cool.  I'm going to end up getting another pair to use for sports in the summer time that has a tighter wrap in a few months.  The ones I'm looking at for that are the Oakley Pro M frame with the Black Iridium lenses.  They don't come in the 24k Iridium, but I have written a note to Oakley (and gotten an initial response back) on the possibility of getting the 24k Iridium lenses in that frame.  We'll have to wait and see on that one.  I'm wearing the Black Iridium lenses already in my Oakley A Frame Ski Goggles.   These were the first Oakley product I had purchased, and I was leery of spending that much on snow goggles ($130 US).  But one trip to the slopes convinced me.   I came home without tired and strained eyes for the first time since I can remember!

It takes some getting used to to wear sunglasses all the time, especially indoors.   I do remove them sometimes, like when I have to do up close work with a circuit board or card, but try to get them back on as soon as possible.  I've also turned of the florescent lights in my office (high source of blue light) when I'm the only one there.

Wearing sunglasses all the time is, for a Stargardt's patient, sort of like brushing your teeth.  It's the long term effect you are after, and there isn't a lot to tell you it's working on a day to day basis.  I arrived at this conclusion independently of any officially sponsored research.  If you choose to follow what I've done, you should do so after reviewing the facts for yourself as I'm not a doctor or medical researcher.  All I know is that my vision appears to be improving.  I've got some theories on why this might be occurring, but I'm not going to post them (as I might be right on my conclusion for the dead wrong reasons!).  So choose carefully, and make an informed decision.


Quote from Dr. Hammer on interim Stargardt's treatment as appeared on the MD Support web site:


The gene for Stargardt's disease has been identified (Allikmet et al.'97
Nat. Gen. 15:236-246).
The faulty gene fails to code for a protein which is present in rod outer
segments only (has not been found in cones,
pigment epithelium or anywhere else in the body). This protein was
thought to be responsible for the active transport
of some substance across the cell membrane.

Recently published findings yield a model identifying this substance as a
compound of a product of the phototransduction of rhodopsin (protonated
N-retinylidene-PE) (Weng at al. '99 Cell 98: 13-23).
As a result, protonated N-retinylidene-PE, a precursor of lipofuscin, is
present in higher concentrations
in rod outer segment discs with the Stargardt's defect than in normals.
These rod outer segment discs are phagocytosed by RPE cells, where over
time high levels of lipofuscin accumulate. High lipofuscin concentrations
in the long term can have 'detergent' like effect, destroying the RPE
cell. These" poisoned" RPE cells in turn



fail to support the existence of the photoreceptors. This is significant
mainly in the perifovea, where rod density
is maximal, leading to the characteristic macular degeneration. This
correlates with histopathological findings of high lipofuscin levels in
the RPE in Stargardt's (and BTW also in some cases of AMD).

At the end of their discussion, the authors predict from their model that
avoiding bright light (and hence the phototransduction of rhodopsin)
would help slow the progression of Stargardt's disease.
I would go one step further than just suggesting dark glasses when
outdoors. In view of the fact that the gene is expressed in rods only and
not in cones, I would consider colored lenses which specifically filter
out wavelengths which stimulate rod vision, while still allowing cone
vision. (Remember the Purkinje shift we once learned about when we
studied the physiology of vision - photopic spectral sensitivity shifted
to the longer wavelengths as compared to scotopic. Rods are not sensitive
to wavelengths exceeding 600 nm, while photopic sensitivity extends to
700 nm).

There are a number of ways of achieving this.
I think that the lenses prescribed need to be individually tailored for
each patient, taking into account his level of 
motivation to slow down the degeneration, balanced against cosmesis,
distortions color vision and functional
visual requirements.
At one extreme would be red filters which don't transmit any light of
wavelength shorter than 600 nm. Although this would be expected to
provide complete protection, and delay indefinitely the progress of the
disease, I think that almost none would wear this. Instead of achieving
100% protection, 0% protection would be achieved.
The other extreme is wearing regular sunglasses when outdoors.

I have an 8.5 year old patient with suspected early Stargardt's. (A patch
of yellow RPE atrophy at the perifovea OS.
OD seems normal. VA 6/9 OU. EOG amplitudes are normal in the dark and in
the light, ruling out Best's disease. The boy's paternal grandmother has
juvenile macular degeneration, with VA's of 6/60 or worse. Although the
patient is not yet showing a classical picture of any particular disease
[not even a retina specialist is able to give an unequivocal diagnosis at
this stage], I am not planning to wait until there is a clear clinical
diagnosis before offering appropriate protection).
I provided him with a pair of lenses with a filter which blocks out all
light shorter than 550 nm (a plastic imitation of the
glass CPF-550. Available in dark and a light version - equivalent to the
darkened and the lightened states respectively of the photochromatic
Corning lens. I chose the lighter version, intending that he would use
them both indoors and outdoors. From eyeballing the scotopic spectral
sensitivity curve, these lenses take care of about 80% of the area under
the curve). I also incorporated his Rx (R +2.00 L +2.50. He rets out as
about R+3 L+4, but what I gave him is as much as he subjectively accepts.
He usually wears no correction, and reads with no problems for hours on
end, finishing several books per week. But once I was giving him
spectacles anyway, I also incorporated the Rx, so he
may be slightly more comfortable).
In practice, the patient uses them only outdoors. They distort color
vision too much to be acceptable to him for full time wear. He was
concerned about the cosmetic appearance of the bright orange color of the
lenses. I provided a regular grey clip-on over the spectacles. This
provides a very satisfactory appearance, and he is comfortable using it
outdoors, although the distortion to color vision is a bit disturbing.
I am considering offering him the plastic equivalent of the light state
of the CPF-115 for indoors use at home.

One could also consider a red contact lens for one eye only, providing
full protection for that eye. The RGP lab I work with tells me that it
has been years since they received an order for one of these lenses. It
used to be used for RP pxs. Cosmetically, they said that the lens is very
obvious on the eye, giving a "cat eye" appearance.

I think there is room for creativity in prescribing appropriate
protection for Stargardt's patients. I will be happy to receive
suggestions from list members (if anyone has persevered through to the
end of this post).

In conclusion, clinical application of the latest research findings
provides hope to patients with early Stargardt's for delaying or slowing
the progress of the disease until gene replacement therapy becomes
available.

Robert Hammer, B. Optom.
Israel
srhammer@netvision.net.il