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Dr. James
Dr. James, Board Certified Ophthalmologist
Category: Eye
Satisfied Customers: 2282
Experience:  Eye Physician and Surgeon
20222826
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I have a few questions about eye tests. I am aware that

Resolved Question:

I have a few questions about eye tests.

I am aware that each line of a Snellan eye chart represents a certain measure of visual acuity in increments such as 20/30, 20/20, 20/10.

I am confused as to which line corresponds to your actual measured visual acuity?

Is it the last line you can read at all, regardless of how blurry it appears?
OR is it the last line you can read without any blurriness?

Or else how do you tell?
Submitted: 1 year ago.
Category: Eye
Expert:  Dr. James replied 1 year ago.

Dr. James :

Hello.

Dr. James :

Thank you for your question.

Dr. James :

Your measured acuity is the line with the smallest letters you can read comfortably. Is is ok to miss one or two letters, as long as you get most of the letters on that line.

Dr. James :

20/20 is considered normal vision.

Dr. James :

You can tell how good your vision is based on the bottom number.

Dr. James :

20/400 is the BIG E. 20/40 is the minimum for a driver's license. 20/20 is normal.

Dr. James :

20/15 is even smaller and better than normal!

Dr. James :

let me if you have any additional questions I can answer. I hope you found me responses helpful and informative.

Customer:

So the line that corresponds to your measured visual acuity is the last line that you can read period, even if the letters are blurry? Just as long as you can read them?

Dr. James :

correct.

Customer:

I have been noticing a slight blur to my vision lately, but it does fluctuate a little. I am trying to determine what my vision actually is.

Customer:

It has been hard to find a way to check online

Customer:

I did find one site that meassures the size of your monitor and tells you how far to stand away

Customer:

on that one I could read the 20/30 line, but with considerable blur

Customer:

the 20/20 line I could just barely make out a few letters, but with a lot of blur

Dr. James :

the size of the letters and how far you stand away is important.

Dr. James :

It is difficult to say if it is truly 20/30 as computer testing methods or iPhone apps are not standardized.

Dr. James :

20/30 is still very good vision however.

Customer:

yeah

Dr. James :

The blurriness you are noticing my be from eye allergies or dry eyes.

Customer:

well it is hard to tell, dryness certainly makes it even worse

Dr. James :

for dry eyes, artificial tear drops will help lubricate your eyes and improve vision.

Customer:

I have noticed some days my eyes are slighntly less blurred

Dr. James :

fluctuating vision is typical for dry eyes.

Dr. James :

where some times it is good while other times it is blurred.

Customer:

it seems to be more so now htough than before

Customer:

never in my life did i feel there was a problem with my vision until recently and it has been over a month

Customer:

I have noticed one strange thing by accident when I was rubbing my eyes in the mrning


 

Customer:

mayeb you have some idea what it means

Customer:

when I very gently press my finger right above my left eye (my dominant eye) on top of my eyeball on the left side my visoin becomes considerably more clear. So much so that the 20/20 line becomes crystal clear, rather than blurred.

Customer:

I mean on top of my eyelid, i dont touch the eyeball

Dr. James :

this may be a sign that you could benefit from glasses.
by pression on the eyeball, it changes the shape of your eyes slightly and gets things in focus.

Dr. James :

see your optometrist to check if glasses can sharpen your vision.

Customer:

i dont have one

Customer:

i have neever needed one

Customer:

I really want to avoid glasses if at all possible becuase i am normally very active and they limit perpipheral vision

Dr. James :

as you age, your eyes changes slightly.

Customer:

im only 31 htough

Dr. James :

good news is that there are many new contact lens options that are very comfortable.

Customer:

i thought that doesnt happen until you 40's

Dr. James :

your eyes changes gradually throughout life.

Dr. James :

faster when you hit your 40s.

Customer:

is there anything i can do to prevent that, or miniimze the damage?

Customer:

I cherish my eyesight and want to doanything i can to keep it

Customer:

not to mention that my career is heavily fdependent on having sharp vision

Dr. James :

a healthy diet will keep your eyes sharp.

Dr. James :

sunglasses with UV protection is a must as well.

Customer:

I have been reading a lot online and keep seeing people mention eye exericse, such as making sure to keep from focusing too long on near objects, and to frequently change focus to keep the eye flexible

Customer:

do you recommend anything specific like that?

Customer:

One thing I am very concerned about is that I have to work on a computer for 5-7 hours a day

Dr. James :

Yes, i do recommend you look away from the computer every 10 to 15 minutes to relax your eyes.

Customer:

anything else that would help?

Dr. James :

frequent breaks, keep hydrate to help prevent dry eyes.

Dr. James :

and the uv sun protection as i mentioned before.

Customer:

what about laser eye surgery?

Customer:

i have read that there is a 95% chance of improving vision, but that the 5% sometimes can have very significant worsening

Dr. James :

yes, what would you like to know about it?

Dr. James :

correct.

Dr. James :

what is your question about it?

Customer:

well several

Customer:

it seems the worst side effects are night vision problems, such as halos, starbursts

Customer:

how can you avoid those?

Dr. James :

choose an excellent surgeon who has done specialty training in refractive surgery.

Dr. James :

the surgeon does many preoperative test to ensure that your will get the best results.

Dr. James :

some patients are higher risks for those problems, so a good surgeon may recommend not to have laser surgery.

Customer:

corneal thickness, and diameter of fully dilated pupils seems the main limiting factors

Customer:

what else is there?

Dr. James :

tear production and regularity of corneal surface.

Customer:

I am veyr much a a night person so the effects of worsened night vision really concerns me

Dr. James :

your vision is very good if you are measuring between 20/20 or 20/30. the good news is that your vision is much better than many people without glasses.

Dr. James :

you are lucky because your have great vision without glasses already!

Customer:

yeah I keep telling myself that

Customer:

but after 30 years of better vision it is impossible to not notice the difference now

Customer:

since I can read the 20/30 line without anything (despite significant blur), and when I press my eyeball I can read the 20/20 line crystal clear, does that mean that the effect I see from pressing the eyeball miught be actually giving a glimpse of what better than 20/20 would be like?

Dr. James :

correct.

Customer:

so would contacts be able to give me better than 20/20?

Dr. James :

hard to say. there is a limit to how small the human eye can see. 20/20 is normal and few people are better than 20/20. it depends more on your eyes rather than contact lenses.

Dr. James :

With the best glasses, I cannot see better than 20/20.

Customer:

well since I can apparently see better than 20/20 by pressing the eyeball, can contacts have that same effect?

Dr. James :

with the best contact lenses, I cannot see better than 20/20.

Dr. James :

possible, but you need to be measured at your eye doctor's office since their letters are standardized.

Customer:

have you had laser surgery done?

Dr. James :

i have not.

Customer:

is there some reason why not?

Dr. James :

my prescription is very low and I only need glasses when driving at night.

Customer:

just interested in why an eye doctor that needs lenses has not had it donee

Customer:

ok

Customer:

im just concerned about safety

Customer:

right now if I could have even a slight improvement I would be ecstatic

Customer:

I hate the idea of glasses because of limited field of vision

Customer:

and since I am so active

Dr. James :

check first with your optometrist to discuss your options.

Customer:

are contacts safe to use with activites like basketball or skiing?

Dr. James :

yes.

Customer:

how ell do they stay in place?

Dr. James :

by the tears and hug up against the eye.

Dr. James :

they fit snuggly on the surface. they come in different sizes and your optometrist makes sure they are not too loose and not too tight.

Customer:

I mean how well do they stay in place, such as with very hard jolts from jumping and landing on pavement, or from sudden jerks from falling while skiing?

Dr. James :

all those activities are fine.

Customer:

I have noticed see slightly better with my left eye, and see much better whe only press my left eyeball

Customer:

wwould I be able to wear only a contact in one eye?

Dr. James :

yes, people are able to wear just one contact lens if they choose.

Customer:

I took several tests online for astigmatism and they seemed to indicate I have slight astigmatism.

Dr. James :

I'd recommend you get an exam with a professional.

Customer:

how well do contacts correct for astigmatism?

Dr. James :

contact lenses for astigmatism works very well.

Customer:

well I will but I am trying to get better informed befre I go so I can ask the right qeustions

Customer:

I have read that contacts need to be oriented correctly in the eye can can slip out of that orientation

Customer:

is that true and how would that be affected by heavy activities such I hmentioend before?

Dr. James :

correct. so getting the contact lens brand and size correct for you is important.

Dr. James :

with a good fit, you should not have any problems.

Customer:

I certrainly hope so

Customer:

if lasik had a quarantee to work I would gladly pay even 10 times the current going rate

Customer:

eyesight means so much to me, but I am so concerned about the 5% that have complications or worsened vision

Dr. James :

Unfortunately, all surgeries have risks. some more than others. good news is that LASIK is a very safe surgery and many people have had it done.

Customer:

can they fix it if somethong goes wrong?

Dr. James :

depends on the complication, but generally yes.

Customer:

I am concerned about the idea of the flap

Customer:

I cant figure out if it is permanent or not, because many people metion that getting hit in the face can cause the falp to come loose

Dr. James :

it takes significant force for the flap to come loose, like getting into a car accident with the airbag deploying.

Customer:

well a ski acccident or getting knocked hard on the pavement while playg basketball is similar force is it not?

Dr. James :

they are less

Customer:

if it is astigmatism that is the problem and I got lasik would it worsen my near or far vision ?

Customer:

I have seen a lot online mentioning that many people that did not need reading glasses needed them after getting lasik

Dr. James :

lasik would IMPROVE both the near and far vision.

Dr. James :

for people over 40

Customer:

no but I mean people that did not need them before the procedure needed them after

Customer:

I would like better near and far vision but near vision is most important

Dr. James :

the issue with reading glasses are an issue for patients getting LASIK who are in their 40s.

Customer:

does wearing glasses or contacts causes your unaided eyes to worsen? Many of my friends sia dthat the felt they did, and I have found some research indicating that they do, but it is hard to make sense of because it seems people are split on the issue

Dr. James :

the answer is no.
what happens is that you get use to the clear vision with glasses or contacts that it is hard to get back to life with the blurry unaided vision.

Customer:

well that is an issue itself

Dr. James :

something to ask your optometrist about.

Customer:

i hate the idea of being dependent on contacts, that is why I am so interested in lasik

Customer:

do you perform lasik, or know people that have had it done?

Customer:

would you recommend it?

Dr. James :

i do not perform lasik. i have many patients and friends who have had it done and they are all very happy.

Dr. James :

i recommend it if you are a good candidate for surgery.

Customer:

none of them had complications?

Dr. James :

no complications in people I know personally.

Customer:

who is the best kind of specialist to determine if you are a good candidate?

Customer:

I want them to consider anything that could cause complications so the risk is very calculated

Dr. James :

a corneal specialist.

Customer:

it is seeming that I will probably try contacts first for a while, and then decide if lasik is worth the risk

Customer:

what risks are there with contactrs?

Customer:

like can they break, or get suck in the eyes, orcause damage to the eyes, etc?

Dr. James :

risk of corneal infection.

Customer:

stuck*

Dr. James :

about 1 in 10000

Dr. James :

breaking and getting stuck in the eye is not very common.

Customer:

how long does it take maintina them/clean them daily?

Dr. James :

takes 1-2 minutes to take them off and put them in.

Dr. James :

you store them in a cleaning solution.

Customer:

is there anything you can recommmend that might be able to improve vision? I have seen aritcles online that the USAir force has vision training programs that are very effective for example

Dr. James :

no, vision training does not work.

Dr. James :

it helps with hand eye coordination, but does not help make things clearer

Customer:

do know of any studies that deomonstrate that? I cant find research proving it or disproving it.

Customer:

but a lot of people sya it works for them

Dr. James :

it is controversial so it's hard to find good research on it.

Customer:

yeah it is frustrating. If there is a chance it could work I wnat to try, but I cant find much research at all arguing either way. But so many people say it works and have been able to reduce their need for glasses.

Customer:

I can certainly feel the muscles in my eyes being worked hard when trying them so they definately do something. Sometimes it seems likke I see slightly improved vision afterwards temporaraily

Customer:

the main things I have tried is changing focus from near to far objects repeatedly

Customer:

i seem to feel a strain inside my eye so I assume that is the muscles controlling the focus of the lense

Customer:

the theory is that this is supposed to increase flexibility similar to changing focus to a far object after staring at a computer

Customer:

are there any supplement that might help? I have found quite a few studies that showed vitamin A, lutein, or zeaxanthin can help? Are you familiar with those?

Dr. James :

those studies are for people with macular degeneration and would not apply to you.

Dr. James :

a healthy diet is enough to maintain good eye health.

Customer:

which foods are best for eye health?

Dr. James :

green leafy vegetables

Customer:

will they improve vision,or just prevent degeneration?

Dr. James :

slows it down.

Customer:

ok

Customer:

oh yeah I had one more question abut lasik. I have seen wavefront mentioned frequentl Many of the doctors that mention it say that it works better and reduces chances of side effects from normal lasik. Are you familiar with wavefront laisk?

Customer:

if so what are the differences?

Dr. James :

yes, it takes a better picture of the surface of the eyes so makes for more accurate laser ablation.

Customer:

is there any risks with wavefront that would be risks with normal lasik?

Customer:

is there any risks with wavefront that would NOT be risks with normal lasik?


Customer:

or is it just better all around?

Dr. James :

risks are the same, just better measurements with wavefront

Customer:

so if cost is the only difference then is there any reason someone should not get wavefront as opposed to normal lasik?

Dr. James :

wavefront is better is you are willing to pay for it.

Customer:

ok

Dr. James :

i have dinner in a bit

Dr. James :

do you have any questions I can answer for you?

Dr. James :

I hope my answers have been satisfactory.

Customer:

yes you have been very he.pful

Customer:

I do have some more questions abut lasik

Dr. James :

ok

Customer:

my understanding is that lasik reshapes the cornea

Customer:

and that there is only a limited areof the cornea that this can be done

Customer:

area of*

Customer:

the limit is a certain diameter up to about 6.5mm

Customer:

when peoplpe have the night vision side effects of halos, starburst, etc, is the reason because the pupil becomes dilated beyond the diameter of the treat area?

Dr. James :

that is a controversial topic.

Customer:

and that since then untreated area is not corrected these abberations are what they would have normally seen acorsss their entire field of vision?

Dr. James :

pupil size in relation to ablation diameter is one factor.

Dr. James :

the regularity of the surface before and after is another.

Dr. James :

dry eyes.

Dr. James :

how the eye heals after the laser.

Dr. James :

so there are many variables in the halos people report

Dr. James :

any other questions?

Customer:

what do you mean b regularity?

Dr. James :

sorry but i am abit short on time.

Dr. James :

how smooth the surface is .

Customer:

is that related to the improvement in wavefront over traditional?

Dr. James :

yes

Customer:

what is normally done at the edge of the ablation zone? Does it abrubtly stop? Or is there a trnsition zone of some sort?

Dr. James :

since i don't do laser surgery, i do not know the exact answer

Customer:

well it just seems that whatever happens at the edge otf the ablation zone is a large factor in detmerining side effects at night sine the pupils are wider

Customer:

Im trying to figure out what they do to correct for that problem to minimize risk of night vision problems

Dr. James :

those are topics still being debated by surgeons.

Customer:

so then there is no way to tell as of yet?

Customer:

but they are working on improving that issue?

Dr. James :

those careful selection criteria such as dry eyes, pupil size, corneal thickness helps to minimize the halos.

Dr. James :

for the majority of patients, they are very happy with the results.

Customer:

that is not very spcific though

Customer:

"happy" is subjective. Does happy mean they can live with the side effects, or that they dont have side effects?

Dr. James :

happy means that if they had to choice to do it again, they would do it again.

Customer:

well thank you for all your answers. youve been very helpful. I have an unlimited subscription so I might be asking some more quesitions another time. I will certainly give you an excellent rating.

Dr. James :

thank you so much.

Dr. James :

all the best.

Dr. James, Board Certified Ophthalmologist
Category: Eye
Satisfied Customers: 2282
Experience: Eye Physician and Surgeon
Dr. James and other Eye Specialists are ready to help you

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