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I've been thru several bifocals over the years. There is generally a period of getting used to the new set and I tried to be patient with my new ones lately, until my metal allergy kicked in. I put on my old ones for the weekend until I could get back to my Optometrist office, where the lady explained that my old ones were titanium and the new ones were not - but there was more. I could still see better in the old ones.Just got my third pair of bifocal lenses a couple months ago. I believe I got my first pair back around 2003. The two prior pairs took me three tries apiece to get them right. This last set, the left lens was good after three tries, but the right took four tries. I don't wear them diving as I use soft lens for that and see great with them. I've been wearing hard contact lens since 1974 so I'm an old hand at them.
The senior doc was out with surgery until next month, but his son did another exam on me - and while he did not say that we made a mistake last month, he let me say it. Not really a screw up tho; just hard to call - long story omitted for this discussion.
Since my old lenses work better for now, and I was allergic to the metal frames, he just gave me a total refund. I'll be back to see them again this year anyway to see how much my new cataracts are developing. I've known many different eye docs in the last 20 years, but been with this one for many years and an quite happy - even tho no one is perfect.
No thanks.
captain
Contributor
I was underwater without a mask swinging my head side to side and blinking. They didn't come out. I wore RGP before soft and with what they cost I didn't want to test them and possibly lose them. With the soft lens I just used a pair I was ready to dispose of to see what would happen.
superman4388
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OP
idocsteve
Guest
I'd like to take a moment to discuss a few important characteristics of soft contact lenses and how they are fit, which makes several posts I have made on this thread a bit easier to understand, and it will give the interested diver more information with which to take to their next visit with their eye care practitioner.
Soft contact lenses have 3 major characteristics that determine how they fit; their diameter and base curve. Thickness and material are also lens characteristics of importance but are not relevant for this particular discussion because they don't affect the movement of the lens all that much.
The base curve of the lens is the radius of curvature of the lens, and for most soft contact lenses ranges between about 8.3 and 8.9, although there are some contact lenses that fall outside these parameters. The lower the number, the tighter the radius of curvature and it naturally follows, that the fit of the lens will be tighter.
The diameter of most soft contact lenses ranges between 13.5mm and 15.0 mm, and again there are lenses that fall outside these numbers but that covers about 98% of contact lenses.
The base curve has a greater effect on how tight a lens fits than the diameter, however a larger diameter lens will be less likely to be washed out of the eye because there is more lens material under the upper and lower lids. Older divers who wear contact lenses may have looser eyelids and therefore may have more of a problem with contact lens loss than a younger diver, all other factors being equal.
For purposes of Scuba Diving, patients may want their eyecare practitioner to be aware of the fact that they are interested in a lens that will be less likely to fall out of their eyes due to unexpected exposure to water and to work in the direction of a tighter fit. A contact lens that is too tight will limit exchange of tears and oxygen to the cornea and may be difficult to remove which can cause irritation or even damage to the cornea.
Patients with contact lenses that are too tight often complain of discomfort or pain only after removing the contact lens at the end of the day.
Soft contact lenses have 3 major characteristics that determine how they fit; their diameter and base curve. Thickness and material are also lens characteristics of importance but are not relevant for this particular discussion because they don't affect the movement of the lens all that much.
The base curve of the lens is the radius of curvature of the lens, and for most soft contact lenses ranges between about 8.3 and 8.9, although there are some contact lenses that fall outside these parameters. The lower the number, the tighter the radius of curvature and it naturally follows, that the fit of the lens will be tighter.
The diameter of most soft contact lenses ranges between 13.5mm and 15.0 mm, and again there are lenses that fall outside these numbers but that covers about 98% of contact lenses.
The base curve has a greater effect on how tight a lens fits than the diameter, however a larger diameter lens will be less likely to be washed out of the eye because there is more lens material under the upper and lower lids. Older divers who wear contact lenses may have looser eyelids and therefore may have more of a problem with contact lens loss than a younger diver, all other factors being equal.
For purposes of Scuba Diving, patients may want their eyecare practitioner to be aware of the fact that they are interested in a lens that will be less likely to fall out of their eyes due to unexpected exposure to water and to work in the direction of a tighter fit. A contact lens that is too tight will limit exchange of tears and oxygen to the cornea and may be difficult to remove which can cause irritation or even damage to the cornea.
Patients with contact lenses that are too tight often complain of discomfort or pain only after removing the contact lens at the end of the day.
diver 85
Contributor
your astigmatism must be of a small amount-----
but, 70% of the population has astigmatism, esp the physiological against-the-rule type...
Herk_Man
Contributor
I am 43 and am saving my money up for longer arms. I don't like putting stuff in my eyes.
OP
idocsteve
Guest
Hey diver85, thanks for your input on this thread. The only thing better than having one eye doctor giving advice is two.
I'd like to elaborate on with and against the rule astigmatism since you brought it up.
Astigmatism is an out of roundness of the cornea and can also be caused by the angle and shape of the intraocular lens. Astigmatism is measured in terms of overall power as well as it's direction, which is labeled in degrees from zero to 180.
Astigmatism due to the cornea can be "masked" to some degree by a contact lens that is spherical and not designed to correct the toricity of the cornea, because it 'drapes' over the cornea and to some extent becomes a new refractive surface. Corneal astigmatism is usually close to 180 degrees and is considered to be "with the rule" whereas astigmatism due to the intraocular lens is closer to 90 degrees and is called "against the rule".
You can test yourself for astigmatism by viewing those square images at the bottom of the above graphic. If, while not wearing any correction, some of the square graphics seem noticeably darker and clearer than others, you've got some astigmatism.
Herk_Man
Contributor
Hmm, you mean they go ON the eyes, don't you?
Smarty.
I don't like that either. Still waiting for a donor of long arms.
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