Laser Refractive Surgery: How is SMILE different from LASIK and PRK? | Mitra Nejad, MD

hello my name is Mitra Nejad and I'm an

associate physician and clinical

instructor at the UCLA Sinai Institute

in the cataract & refractive division

today I'd like to discuss laser

refractive surgery specifically I'd like

to introduce you to a new surgery called

smile and discuss how it's different

from the other better known laser vision

correction procedures feel free to ask

questions on twitter using hashtag UCLA

md chat or comment on facebook so in

today's talk we're going to discuss

who's a candidate for laser refractive

surgery we'll also discuss the more

popular laser vision correction

procedures and we'll go over the

advantages and the disadvantages of each

so patients who are seeking laser vision

correction usually have a symptom of

blurred vision and this is blurred

vision that gets better if they wear

their contacts or their glasses this is

something we call a refractive error

because it has to do with how the eye

bends or refracts light the most common

type of refractive error is

nearsightedness or myopia in this

condition the eyes optics are too strong

and they're bending light too much or

the eye is too long so that the light

comes into focus short of the retina in

this condition patients feel like their

distance vision is blurry but that their

near vision is very good the opposite

refractive error is farsightedness or

hyperopia and in this situation the eyes

optics are too weak or the eye is too

short so that the light comes into focus

behind the retina patients with hyper

appeals will feel like their distance

vision is good but that their near

vision is blurry in severe hyperopia

they'll feel like they're distance

vision and their near vision is blurred

but usually the near vision is more

blurry a third type of refractive error

is called astigmatism in this condition

the light comes into focus at two

separate points creating a blur this is

often because the front surface of the

eye the cornea instead of being

perfectly spherical shaped like the top

of a basketball is actually a little bit

steeper in one direction than the other

kind of like a football and this

actually will distort vision at all

distances so distance

intermediate so if a patient has the

appropriate refractive error and they're

seeking to get out of their contact

lenses or their glasses and their

prescription has been stable for a year

or more they could be a candidate for

laser vision correction as long as they

don't have other major medical problems

or major eye conditions and that's why

it's important to come in for a

screening exam where we can look for

things like glaucoma retina pathology

and really take a good look at the

cornea at the front surface of the eye

where the operation is performed to make

sure there are no irregularities or

abnormalities so the first type of laser

refractive surgery that I'd like to talk

to you about is called photorefractive

keratectomy or PRK in this procedure the

most superficial layer of the cornea

called the epithelium is removed and

then a laser is used to reshape the

cornea followed by placement of a

bandage contact lens the advantage of

the surgery is that it's safer for

patients with thinner corneas because we

have to manipulate less tissue it's also

been around for almost 30 years the

disadvantage is that it takes the vision

a while to recover so it could take up

to a week to feel safe driving it could

take up to a month or two to get that

perfect vision patients will experience

some intermittent light sensitivity

tearing burning for that first few days

while the contact lens is in and there

is a risk of a transient ocular dryness

that can last three to six months rarely

up to a year the second type of laser

refractive surgery is lasik which stands

for laser-assisted in situ

keratomileusis in this surgery we use a

laser to create a flap of tissue in the

cornea and then we use a second laser to

reshape the cornea and then we replace

that flap back down this is probably the

most commonly used procedure for

nearsightedness farsightedness

astigmatism and it's probably the most

popular because the vision is usually

excellent the next day now patients will

have a few hours of burning and tearing

immediately after the procedure and

we'll often advise them to go home and

take a

nap and it does have the similar kind of

ocular dryness risk that PRK does the

third surgery I'd like to introduce you

to is called small incision lenticular

extraction or smile now this is an all

laser procedure using a specific laser

called the vision max which is only

available at a few centers in Los

Angeles UCLA being one of them it's been

available internationally for over ten

years so there's great studies showing

similar safety efficacy and

predictability to LASIK it was FDA

approved for myopia in the United States

in 2017 and for a stigmatism in 2018

this is an animation video of smile so

I'm going to talk you through it the

laser is going to create a lenticular

disk shape tissue in the cornea it's

also going to make that small incision

which is about three millimeters the

surgeon can then access this lenticular

disk shape of tissue through that small

incision and remove it from the cornea

this allows the cornea to flatten that

appropriate amount that we need to treat

your nearsightedness or your stigmatism

of all the surgeries smile has the

shortest duration of burning and tearing

maybe an hour - it does have a medium

visual recovery time so it's not as fast

as LASIK but it's not as slow as PRK

most patients feel like they're seeing

very well within two three days of all

the surgeries this has the lowest risk

of dry eye because that incision is so

small and for the same reason it's

thought to have a less of a

biomechanical effect on the cornea so

it's thought to be safer in patients who

have higher levels of Correction that's

needed so in summary patients who have

have refractive errors and desire to get

out of their glasses or their contacts

they've had stable prescription and they

have no other medical eye conditions can

be candidates for laser vision


all three types of laser vision

correction can be excellent smile LASIK

and PRK and the patient and the surgeon

can decide together which is the most

appropriate procedure for that person

feel free to ask questions on Twitter

I'm going to be taking a few questions

now let's take a look here okay our

first question is is there an age limit

to laser refractive surgery so it's a

very good question

technically all of these surgeries are

FDA approved for patients 18 and older

but there's a couple caveats the first

is that your prescription has to be

stable and often that takes into that

early mid-20s for that to happen on the

upper side of things I mentioned that

you can't have any other medical or eye

problems and often in the 50s is when we

start to see the earliest signs of some

of these things

so again patients over 50 should first

have a comprehensive eye exam to make

sure that they don't have any other

issues with their eyes see if there are

any other questions can you have laser

eye surgery at the same time of cataract

surgery so that's another very good

question the answer is yes to a degree

we can do laser procedures at the same

time of cataract surgery to try to

minimize your need for glasses but it's

very different from the procedures that

we talked about here that's something

that you can discuss further with the

surgeon that is doing your cataract

surgery if you are interested in being

glasses independent after the surgery I

think that's all the time we have thank

you very much for tuning in and feel

free to continue to ask questions