|
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.
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 |