Ask the Doctor of Optometry [formerly student]

Ferret Herder posted:

Ha…I used to not warn people about the air puff when doing non-contact tonometry, as a classmate pointed out that you get results more easily when people aren’t expecting the puff (for the first eye you test, anyway.) Then I had someone fall right off the chair. Now I tell people to expect a puff.

needscoffee posted:

Most places use a projector or a computer screen, and having the lights out improves the contrast of the letters. On the other hand, plenty of people see worse in the dark for various reasons. Lens changes are a significant factor here, as glare tends to be worse when the pupil is large (i.e. when the lights are off).

Not all places turn the lights off when checking acuity. Actually, the low vision center I’m externing at now uses an “ETDRS” chart which is softly back-lit with black letters and we test with the lights on. Generally people do better with this test than they do with standard projected Snellen (the common eye chart with the big “E” on top.) Moreover plenty of projectors have quite poor contrast of letters, even with the lights off, and people with ocular disease often suffer from reduced contrast acuity to begin with, so their projected Snellen acuity is actually an underestimate of their true acuity – this can make a big difference if they’re trying to, say, qualify for a driver’s license.

congodwarf posted:

Biology.

I was interested in the career ever since I was little, since I visited one every year (I’m pretty nearsighted). I wouldn’t say that I wanted to be an optometrist ever since I was little, though. My dad is a nurse and I think for that reason I always wanted to go into the health professions; it just took me a while to pick one! But I decided on optometry my junior year of college. The pre-reqs for all the doctoral level health professions are pretty much the same, so there wasn’t a rush to settle on a choice while I was in college.

Well, I have the pre-reqs completed because, as I said, they are similar to the optometry school pre-reqs, but that’s pretty much it; there’s no direct optometry-to-ophthalmology path. I’d have to apply to medical school and then, after medical school, complete an ophthalmology residency. I’m not sure I would have the patience for all that schooling at this point. Not to mention it’s rather competitive to match into ophthalmology!

Pretty much a straight path. I took a year off after college to teach Biology labs and work in a neuroscience/psychology research lab while I applied to optometry schools, though.

Hmm. I’ve seen some really gooey, purulent bacterial conjunctivitis cases. One person had a large bleb (from a trabeculectomy surgery) that was basically overgrowing the cornea, and that was lovely. The scariest, reddest eye I’ve seen was also a blebitis that looked like it was about to turn into an endophthalmitis, if it hadn’t already.
I’ve never seen a phthirus pubis infestation of the eyelashes, (aka eyelash crabs!) but those are some nightmare inducing textbook pictures, let me tell you. Here’s a nice photo if you’re curious:
http://www.opt.indiana.edu/riley/HomePage/Anterior_Segment/Graphics/279_alph_crab.jpg

Maybe eventually, but not immediately. I think it’s more useful to work for someone else when you finish your training, so you don’t have to worry about the business aspects of things right away. Right now I’m applying to residencies.

I was doing ok until you got to the crabs. Ever since the headlice incident of 1990, I have issues with the idea of creepy crawlies in places they shouldn’t be. Ick. I’ll stick with pus thanks. :smiley:

Thanks for the answers, and the thread. This is very interesting. I hate going to the eye doctor because I always feel like I’m going to fail. I hate being so near-sighted but I’m afraid of surgery (and the cost).

Trust me, eye doctors are pleased if your vision can be corrected to 20/20 (or thereabout), regardless of whether you need glasses or contacts or whatever to do it. One of the ophthalmologists I work for has said what great vision various patients have, and they look at him like he’s crazy because they have glasses. Considering he’s got a lot of patients who can’t get near 20/20 because of some awful eye problems, needing glasses is fine!

(I’ve needed glasses since 4th grade, so I used to think my vision was “awful” too. Now I’m pretty much OK with it!)

Well this is supercool, thanks for starting the thread!

I hate my glasses, so I mostly just don’t wear them.

The problem is that I need distance and reading in the same lenses so I can see what I’m writing and be able to look up and not have to take off the reading glasses to see the thing or person in front of me, does that make sense? This comes up quite a bit both at work -helping someone fill out a form or reading a form while having a conversation with someone- and at school -taking notes and reading the power point at the front of the classroom-.

The problem is that with the glasses I have the distance part requires tipping my head down to look through the top and the reading part is just a teetiny section at the center of the very bottom so I have to tip my head way up to read anything. It’s frustrating and probably makes me look like a dork :wink:

When I mentioned this to my eye doctor he suggested I take some time to try to get used to them, and I just never did. What I really want is glasses that are 2/3 distance and the bottom 1/3 for reading, that seems like it would work really well but I have no idea if I can actually get someone to make those for me.

Should I keep wearing them because he’s right and I will get used to them or should I find another eye doctor and start from scratch?

moejoe posted:

It sounds like, from what you’re saying, that you’re probably wearing progressive lenses (although you might just be wearing bifocals with a small lens size in the up-and-down direction, or what’s know as a small “B size.”)

If you’re wearing progressives, it sounds like you’re having trouble adjusting to them and your needs would be better met with bifocals. These are commonly fit with the top of the bifocal at the level of your lower eyelid, which should be adequate for what you’re describing. If you go back to your doctor and mention that you’re still having difficulty with the progressives and want bifocals instead, they will probably work with you to switch them, assuming it hasn’t been too long since you first got the progressives. Some people simply can’t used to progressives; that’s just the way it is.

Remember that the issue with bifocals is that you can see the “line” that divides near and far portions of the lens, and that bothers some people for reasons of cosmesis. If that sounds like something you wouldn’t like, one possibility is to ask for either a blended bifocal or a “round seg,” as these are generally less obvious. They won’t have the perfectly smooth look of progressive lenses, though.

Finally one thing I’ve noticed is that when people pick progressives with small “B size” frames, sometimes part of the reading portion gets cut off in the making of the lens. I know frames with small lens sizes are in fashion now, but whatever type of lens you get, if you need a bifocal or progressive, try to find a larger B size as it will give you both more room to work with in the distance and while reading.

Just a quick question here - how bad does my near-sightedness has to be before lasik and other eye surgeries wouldn’t help to improve the situation?

So then I take it there is nothing remarkable about me being able to read microprint when others need to read it using a magnifying glass???
Darn…and here I was ready to use my powers for good not evil.

Hello my question is, do I have to replace glasses and contacts each year? Before I did contacts 3 yrs ago, I would have glasses and only change every 2-3 years. Now I’m getting new pairs plust contacts every year, that it is draining my budget. I was hearing how folks just wore contacts all the time and having changed glasses in six years (as those were truly back up). I wear contacts during the day and switche dto glasses evenings.

Have you received any instruction in the area of “vision training” particularly in regard to learning disorders, e.g., dyslexia?

There are several practitiioners in my area that offer this serivice and I’m not aware of any research to support it in cases where there is no obvious ocular-motor problem.

I’ve got three (real) questions (and a seconding and a random curiousity)

  1. Why do I have different prescriptions for each eye? I’m nearsighted in one eye and astigmatic in the other - what the hell causes that?

  2. Whenever I’m in a movie theatre or somewhere dark (even somewhere like a mall or a restaurant with low lighting) for longer than about 15 or 20 minutes and then I walk outside into full sunlight, I’m blind for the next 5 to 10 minutest - I literally can’t open my eyes because the sunlight is too bright, and I have tears streaming down my face - I know some people are light-sensitive, but is seems extreme to me. Is this still ok? I feel like a freak.

  3. I don’t have progressive lenses, but there is a notable difference in how well I see when I look through the top portion of my glasses when compared to the bottom. Are my eyes different prescriptions on the tops and bottoms, or are the glasses doing this?

(Also, I’d like to second the request for info on how much Lasik can fix really bad eyes, or astigmatism, especially in eyes where it’s just continually getting worse.)

(Finally, general curiousity question - one of my friends has different colored eyes (blue and green) - how common is that, and are they more likely to have different prescriptions?)

I know that pregnancy can cause vision changes, but by what mechanism? And how long after delivery does it take to go back to normal or settle into a new normal?

Crowbar of Irony +3 posted:

Pretty damn bad? There isn’t a set number for which LASIK no longer works – it’s a relationship between the thickness of your cornea and the amount of diopters of correction you’ll need. That’s because the procedure involves thinning and reshaping the cornea, and the amount of tissue removed is proportional to refractive error. I would say that at about the -7 to -9 diopter range, corneal thickness becomes an important issue, and patients may have to have PRK done instead of LASIK. But again, some people with lower amounts of nearsighted won’t qualify for LASIK, and some with higher amounts will.

PRK is a laser surgery that takes longer to heal and by most accounts is more painful than LASIK, but no flap is made, so thinner corneas / greater refractive errors are acceptable. There’s some people who believe the results are more stable because there is no flap. Corneal thickness is still an issue, though. As for upper limits, the number varies by sources (and different surgeons probably have different comfort levels,) but some people can have this procedure done in the -11 to -13 range, and I’m sure if you search you will find people who have done it for greater amounts of myopia too.

After that, there are a variety of more complicated surgical options, such as implantable contact lenses, “clear-lens extraction” (in which the healthy, non-cataractous lens is removed and a lens correcting the patient’s refractive error is implanted) and “phakic intraocular lenses” which are implanted lenses placed in between the iris and the patient’s own lens, which is beneficial because the patient can still change focus, assuming they were young enough to do so before the surgery.
smokey78 posted:

If you’re happy with your vision in your glasses, you don’t have to replace them. You might participate in activities (such as driving) where clear vision is advisable, and it’s probably a good idea to update your eyeglass prescription if there’s a noticeable change, but you don’t have to, and if you’re an adult you won’t make your vision permanently worse by wearing an old prescription, assuming you’re not crashing into things and bumping your head.
Contact lenses are a different kettle of fish. You should go for an exam every year to evaluate the fit and prescription (and to check the overall health of your eyes.) Ideally, you’d be changing the contacts more often than once a year – the monthly, bi-monthly or daily contact lenses are simply better for your eyes and have a lower incidence of complications, such as eye infections or contact-lens associated allergies.
Kelby posted:

We were taught that vision therapy/vision training doesn’t help dyslexia or other neurological issues, but that on occasion dyslexics can have concurrent oculomotor problems that interfere with reading, and occasionally children who have an oculomotor problem (such as a convergence insufficiency or intermittent strabismus, etc) might be misdiagnosed as dyslexic.
A significant portion of class time of our vision therapy coursework went into differentiating oculomotor and perceptual disorders, so that parents could be educated as to the cause of their child’s difficulty with reading (and a referral to a reading specialist or pediatrician could be made if dyslexia is suspected), so no, we weren’t taught to use vision training for dyslexia, although I suppose some people do. In general there are some of my professors who think vision therapy is useful for a very short list of conditions, and some who think it’s useful for a somewhat longer list of things – there’s some controversy, especially in terms of kids with difficulty with saccaddes, fixation, etc. But I haven’t met anyone who said “vision therapy is good for dyslexics.”

Ooh, I was waiting for this thread for a long time!

  1. About the ETDRS chart mentioned up thread, why don’t they have different sets of letters for each level, so that the doctor can mix it up?
    When I had my eye examined recently, I had almost memorized the arrangement of letters after a couple of tries. I had to consciously block out my memory to make sure I was reading the actual letters.

In Japan (Maybe other places too), they have an interesting alternative. The charts have a bunch of letter Es in different directions. And you have to tell which direction the character is facing (up, down, left or right). Marginally better, but still has the same problem as above.

  1. During my eye test, I remember seeing a picture of a house that went in and out of focus a couple of times (I’m guessing these tests are pretty standard, so you can tell what I’m talking about). Any idea what that was about? Since it was early in the test, I assumed that it was some kind of calibration.

Thanks!

**Lasciel **posted:

Most people don’t have the exact same prescription in each eye, although both eyes tend to be similar. Sometimes they’re very different due to a structural abnormality, such as unilateral microphthalmos. Mostly it’s just luck, I guess. I don’t think anyone really knows why it happens. It’s possible strabismus, (i.e. an eyeturn,) could lead to a change in prescription due to one eye being favored more than the other, but I haven’t seen any studies to that effect.

There are certain disease states that can lead to extreme photosensitivity. These include uveitis, retinitis pigmentosa, moderate to severe glaucoma, and about a gazillion other things.

Is it new? If you said “no, It’s always been like this” I’d be less worried than if you said “It started a month ago.” Either way if you’re concerned, you should visit an eye doctor. But yes, it is possible that you are simply that sensitive to light, particularly if it’s the only eye-related symptom you have.

Aberrations can occur when you look away from the center of the lens. The affect is more noticeable with higher prescriptions and astigmatism, and also depends on the material the lens was made out of. In theory this should be the same from top to bottom, but you may not be looking the same distance away from the optic center when you look at the top vs. the bottom of the lens. So it’s just the glasses doing it, in all likelihood.

See above! Most doctors will not perform surgery on someone for whom it’s “just continually getting worse,” because such a patient might require repeat surgeries, and the risk of adverse effects increases with repeat surgeries in LASIK and PRK (and most things, actually). Many ophthalmologists will require your prescription not have changed by half a diopter or more in the past year.

Apparently “heterochromia irides,” which is the technical term for what you’re asking about, affects less than 200,000 people in the U.S. Just so you’re not too impressed, I had to look up that fact on Google; I didn’t know it off the top of my head. I’m honestly not sure if they are likely to have different prescriptions, sorry! I do know that this can either be as a result of an abnormality (such as congenital Horners syndrome, or Wardenburg syndrome, or a few other things), or it can just be a genetic trait with no accompanying eye-related or systemic problems.

Some medications (such as the prostaglandins, used to treat glaucoma and also, recently, to grow eyelashes longer, as in Latisse,) can cause the iris to darken, so someone using such a medication in just one eye could potentially have different colored irises too.

RoniaBorkason posted:

There are a lot of potential changes to the eyes during pregnancy, probably too many to list here. Most commonly, hormonal changes can lead to dry eyes and resulting discomfort, corneal swelling, and even changes in corneal curvature, which could potentially change a patient’s prescription. From what I’ve learned, these changes tend to reverse after pregnancy. As for the exact amount of time that takes, it really depends. Breastfeeding can prolong the vision changes (it’s not bad for your eyes, but it might take them longer to settle back to their old prescription. I wouldn’t use that as a reason not to breastfeed though!) Finally, although it’s less common, some patients have reported permanent changes to their eyeglass prescription after pregnancy.

More serious issues can affect the eyes; for example, patients with diabetes are more likely to experience episodes of uncontrolled blood sugar during pregnancy. This can lead to lens swelling and diabetic retinopathy (or worsening of these things). Patients with gestational diabetes only are less likely to have it affect their eyes, but it’s still a possibility. Because of this, it makes sense if you notice your vision is blurrier while pregnant, not assume it’s normal pregnancy-related changes, but to get a dilated eye exam to make sure that’s all it is.

A few questions -

I if try to stop blinking after about 20 seconds or so my eyes start to hurt and I have to blink to stop the pain. What is causing the pain? Is it the tears evaporating and my eyeballs becoming dry? How long would my eyes have to stay open before I would cause temporary or permanent damage.

If I am looking at a white wall I sometimes notice what seems to be a lot of floaters which can become distracting, they don’t normally bother me though. Is there any kind of measurement that indicates if somebody has an excessive number of floaters and are there any potential problems caused by floaters. I was also told that short-sighted people like me tend to have more floater because of a slight tug experienced by the retina - is this true?

How tough are eyeballs? Before I started wearing contact lenses I was very squeamish about touching my eyes as it seems a lot of people are but after a few months touching my eye was not a big deal anymore . Once I even spent a couple of minutes trying to remove a contact lens that I had already taken out and it didn’t seem to bother my eye at all. It seems to me that eyeballs can get slight damage and they will heal without any problems. If I slightly cut my eye, let’s say a cat scratched the surface but didn’t puncture it, and it didn’t become infected would it heal properly?

Thanks

Huzzah! Thanks for the answers, that was cool!

Zerc, I believe an eye doctor can look inside your eye and see your floaters, after dilating your eye, etc.

I read quite a lot about how near-sighted people tend to have more floaters, but no explanation as to why this is. Should I be careful about working out or playing tennis because my near-sighted eyes might be more prone to damage? How about a dental drill shaking my skull?

I can live with my floaters but I’m afraid that I’ll get one (or more) that isn’t annoying but disabling and then I’ll be told to live with it. Is this possible? And since I notice that I only tend to see the floaters when I’m looking at a bright screen, is it possible to diminish the strength of the floaters by wearing dark or tinted glasses, thereby minimizing the shadow?

By the way, what’s the latest on those contacts you wear at night that shape your cornea so you can see lenses-free throughout the day? I like my eyeglasses but I find this technology interesting.

chromaticity posted:

Are you saying each line, or level of acuity, had the exact same letters in the same order? I’ve never seen a chart like that before. Some people do memorize the most common charts, like the EDTRS or Snellen, either intentionally or simply because they’ve had so many eye exams. There are computerized vision charts that can be randomized and are a good option for such patients.

That was probably an autorefractor. It’s used to get an estimate of your eyeglass prescription as a starting point.

Zerc posted:

The discomfort is related to the drying out of the surface of the cornea, yes.
I don’t know how long you’d have to hold your eyes open all at once for that to cause a problem, but patients with a reduced blink rate, or incomplete blinking, or a lid abnormality, can have a condition called exposure keratopathy, in which the cornea is damaged due to chronic dryness. In general chronic dryness of eyes will cause more trouble than, say, holding your eye open for one minute will (not that I imagine anyone would try that unless they had to for some kind of procedure.)

It’s a good thing that we feel that discomfort that causes us to blink; patients with reduced sensation of the cornea will blink less as a result, and that’s one of the contributors to a serious type of corneal ulcer (a neurotrophic ulcer, if you’re curious) which can occur after eye infections, particularly ocular herpes.

I don’t know about a particular way to measure the number of floaters; they are visible when we look inside the eye during ophthalmoscopy, so in general we can tell if you have them. Some are easier to visualize than others. A big detachment of the vitreous (the jelly-like substance that fills up most of the space in the eye) is easy to see. The little floaters that many young nearsighted patients have are harder to see. One of my supervisors actually found the HRT (an imaging device used for glaucoma) to be the best way to visualize a patient’s floaters.

You’re right that nearsighted people tend to have more floaters and they tend to experience them at a younger age. That’s because nearsighted people have, on average, longer eyeballs, and the vitreous is more likely to be pulled or tugged away from the retina; it also may liquefy at a younger age.

The white part of your eye (the sclera) is about 1 mm thick although it varies depending on where you’re measuring in the eye, and extremely tough. The central part of the cornea (the clear part) is about half a mm thick. It’s also tough, although it can get scratched fairly easily, but the cells that make up the most superficial layer heal very quickly; superficial scratches to the cornea will often heal without any scar within 24 hours. In fact, when I first started learning tonometry and gonioscopy, I practiced on my classmates, and we would often leave each other with superficial scratches to the corneal epithelium that thankfully healed up quickly and scarlessly :wink:

Deeper scratches that penetrate past the corneal epithelium (the most superficial layer) will take longer to heal and will leave a scar, although it might not be visible to the naked eye.

A cat scratch is the sort of thing to watch very closely, due to the possibility of bacteria introduced into the wound or, depending on whether the cat goes outdoors, something like a fungal infection or acanthamoeba, etc. This may go without saying, but the deeper a cut or scratch to the cornea, the greater the possibility of an opportunistic infection. If the scratch was only to the epithelium and didn’t penetrate into deeper layers (Bowman’s layer, or the stroma, or the endothelium) and as you said there was no infection, then yes, it would heal properly and scarlessly in all likelihood, assuming the eye was healthy in other respects.

What do they call those eye mapping machines? They have a hole you stick each eye up to and the doc moves your head around a bit and out pops a detailed picture of your inner eye. That’s a very technical description I know.:smiley:

Are “artifacts” common? What are they? While examining the picture up on the computer screen, the doctor saw a white speck in or near a capillary that she suspected could be either cholesterol or an “artifact” and she would consult with the main doc and call me if anything serious turned up. I never got a call back. I should have taken initiative and called the office later that day, but I really just kind of forgot. I don’t have cholesterol issues and my vision hasn’t worsened noticeably in the year since then.