More on the contact lens thing

imported
#1

I posted this to the previous thread, but it is now on the 2nd page so I started a new one.

Yogi – you are correct that the old type of lenses did not allow enough oxygen to the cornea/lens. The newer, extended wear lenses are designed for 24 hr wear, and for up to 2-4 weeks. As I previously posted, most contact wearers have protein or lipid build up which limits wear to a few days. I am lucky that I get neither. When they get build up, they have a foreign body sensation, or notice a slight decrease in acuity. For day to day wear, it is a fine idea to remove lenses at whatever interval you feel comfortable. Again, I am not advocating that everyone leave their lenses in for their entire thruhike, but certainly for the 4-6 days between town stops, it is probably just as safe, if not safer, to leave extended wear lenses in, (as long as you do not experience the irritation sensation etc., keep them hydrated when necessary with saline drops) than it would be to recontaminate them by cleaning them in the field and then replacing them in your eyes every day with less than perfectly clean hands. And to Bramble, an optometrist is not a physician, an Ophthalmologist is. 20 years ago, extended wear lenses did not exist and the lenses today are much improved. Most of us need reading glasses after 40 or so anyway because of presbyopia, where in the lens becomes too stiff to focus on close up materials. I can tell you, that I see my Opthalmologist every year, and although he would not recommend wearing lenses for a year as I sometimes have, he has found no problems in my eyes as a result of wearing them for more than 15 years like this. I also leave my lenses out for a few days when I remove them, perhaps that is part of the reason I have no problems long term. The only real issues that are shown in the medical literature to arise are corneal infections/ulcerations, which result from improperly leaving lenses in when irritation/red eye is experienced and ignored by the wearer. I have probably posted way too much on this topic, but would be happy to answer medically related hiking questions for the forum. Im sure there are other MD’s here who just havent identified themselves as such.

cutman11

#2

To help the layman understand this, an ophthalmologist is an MD who had gone through medical school and can do surgery on the eyes (such as cataract surgery and lasik) and prescribe medicine as well as determine your eyewear prescription. Most of the ophthalmologists I’ve worked with don’t fit contacts but give the patient the green light to be fitted for contacts elsewhere by an optometrist or certified contact lens fitter (meaning, the eyes/corneas are in good shape, you go from here). An optometrist is an OD who has gone to a four year post-graduate optometry school and can prescribe glasses and contacts as well as diagose and treat many medical eye problems (in most states), but may refer a patient to an ophthalmologist if the problem is something he/she cannot treat.
The average person who wears contacts is more likely to be fitted by an optometrist. Their offices are generally more convenient and accessible and the exams tend to be less expensive.
Many eye problems occur from improper wear and hygiene; most are anecdotal and not in the medical literature. I’ve worked with optometrists for 20 years and was a licensed contact lens fitter for 8, so believe me when I say that many people are nonchalant about their cl wear until they come in with problems due to overwear and I’ve seen it numerous times. Many of the new contacts are great, but some have been out for a while. The B&L optimaFW, a popular inexpensive disposable, has been around for over 20 years in one form of packageing or another. Ciba N&D and Acuvue Advance as well as others are designed to reduce problems, but you can still overdue it, depending on your eyes, the protein in your tears, how easily your eyes dry out, etc.
Whether you chose an optometrist or an ophthalmologist, follow their advice, not the word of something you read on a forum.

Bramble

#3

I was talking with my opthalmol. colleague today about this thread, and he did suggest adding one caution: at high altitudes (8000+ ft) the oxygen getting through the contacts would definitely become an issue, particularly if the lenses were not hydrated enough, so I guess in the higher elevations out west, leaving contacts in would be a no no. In that case, I would probably forgo the contacts altogether as infection risk would be much higher if one were removing lenses in the field frequently.

Cutman11