What is a Prism Anyway

A few weeks ago I posted a picture of me holding a prism bar.
What is a prism
That pic is the most popular one I have on IG so far. I was really surprised. This little piece of plastic, is not as sexy as the fancy laser machines that most ophthalmologists use for LASIK or laser cataract surgery. Usually people (or other non-strabismus ophthalmologists) run screaming if they even hear the word prism! But, I think there are a lot of people interested in what they are and why I use them.

Strabismus is when the eye wanders in or out and often patients with strabismus experience double vision. Just think for a second how debilitating that is – to see two of everything. Here is a pic of crayons I took.

Now imagine, if you had double vision. Like this.

And, if I said, hand me the red crayon – you wouldn’t know which one to grab – where is the real crayon and which one is just a second image?
It’s no wonder that most of my patients are so miserable and are so happy to be offered glasses or surgery.
Prisms help me measure the amount of deviation. I use them in my office for 2 different reasons. There are horizontal and vertical prism bars to measure if someone’s eyes deviates horizontally (crossing in or wandering out), or if it drifts up.

If the patient is happy in glasses, then I can put a stick-on prism, called a Fresnel prism right on to their glasses, like a window decal. This gets rid of the double vision. It’s kind of crazy, amazing. Somehow, someone, figured how to convert that thick triangle piece of plastic in a prism bar into a flat sticker!

Once I have a prism measurement for the deviation, I can also plan surgery to correct the lazy eye. I can then consult a table, and determine how many millimeters I’m going to tighten or loosen a muscle based on their prism measurement. Strabismus surgery is just so life changing, for both kids and adults. It’s why I wanted to specialize in pediatric ophthalmology and adult strabismus.

And, here’s the thing – it is NOT cosmetic. For kids, it truly changes the way they interact with their environment. I’ve been told time and time again, from parents when I operate upon their babies and uncross their eyes – that they are now walking whereas before they were only crawling or now they can pick up Cheerios which they could never do before.
But, equally as gratifying is performing this surgery on adults. I had one woman who came into a consultation with me and she literally cried when I told her I could help her. Everyone else had said that surgery was not an option for her (not sure why!). There’s such a misconception out there that someone can be “too old” for this type of surgery. Or that insurance doesn’t cover it because it’s cosmetic. That is NOT true! This surgery is not cosmetic, it is reconstructive. Our eyes were meant to be straight. I give talks to optometrists and ophthalmologists, as well as other physicians, to hammer this point home. Almost all medical insurances cover the cost of the surgery and that is because having a lazy eye has been proven to affect self-esteem and even job hiring and placement. ⠀
This is Keith, one of my patients, and I’ll just show you a before and after pic, that he took himself and let him speak for himself.

Keith writes “Since I was born, I struggled with amblyopia (lazy eyes) and strabismus (crossed eyes) in both my right and left eye. I went through every treatment imaginable throughout my childhood. Eye patches, surgery, glasses, more surgery, eyeglasses with one side blacked out, holistic healing, my parents did everything they could to get my eyes straight. After years of corrective procedures, the right one was straight but the left one (the stubborn one) refused to collaborate with my right eye in any way shape or form.
At 30, I had come to accept that my eyes just were not going to work right regardless of what treatment I received. I was just going to have to deal with the headaches and double vision.
I went to Dr. Rupa Wong for a standard checkup to get my new prescription for my terrible eyeballs, and halfway through my examination, she mentioned that she specialized in strabismus surgery, and could absolutely fix my left eye. I was skeptical, all I had been hearing up to that point from a number of specialists was “it was the best they could do” and “closest it could get” to being straight. Still, I went through the process of getting evaluated and scheduled a surgery on both eyes to fix the issue.
Dr. Rupa’s confidence throughout the process, from the evaluation to the pre-surgery, to the day of, got me through the unfathomable anxiety I was feeling up to that point. I wanted to bail 1,000 times, and actually did for the first surgery, but her reassurances actually got me to the surgery center in October 2017. I was terrified.
The 2.5-hour surgery could not have gone better. I felt no pain or grogginess, it was over (to me) in a matter of seconds. When I woke up I was floored at how straight my eyes were. I actually started crying because for decades I believed it would never happen. Thankfully, it went unnoticed because my eyes were bleeding. Even the recovery was (mostly) painless.
My eyes are now 100% straight, I am much more confident on a day-to-day basis, my headaches and double vision are completely gone, and I have a new lease on life.”

So, there you go. If you can remember only one thing from this post it’s that strabismus (or lazy eye) is NOT a cosmetic problem and that there are glasses or surgery to fix it. Bottom line, get checked by an ophthalmologist who specializes in the treatment of strabismus. Click here for a full list of fellowship trained physicians.

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Dr. Rupa Wong


Hi! I'm Dr. Rupa Wong. Physician. Private Practice Owner. Mama to 3 kids. Managing Partner. Educator. Textbook Author. Conference Co-Founder. Mentor. I am more than just one thing, even as a doctor and I bet you are too. I would love to help you envision the life you want, and then get after it. What are you waiting for?

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