Merck Manual

Please confirm that you are not located inside the Russian Federation

honeypot link

PODCAST Strabismus with Dr. Leila M. Khazaeni

01/03/24 Leila M. Khazaeni, MD, Loma Linda University School of Medicine;

Season 5 | Episode 5


Joe McIntyre (Host): Welcome to another episode of the Merck Manuals Medical Myths Podcast. On this show, we set the record straight on today's most talked about medical topics and questions. On this episode, we're taking a closer look at strabismus, which some listeners may know as cross eye or wandering eye. I'm your host Joe McIntyre, and I'm joined by Dr. Leila M. Khazaeni, a distinguished expert in the field of ophthalmology with a primary focus on pediatric ophthalmology. She's an associate professor of ophthalmology at Loma Linda University School of Medicine. Dr. Khazaeni, thanks for joining us.

Leila M. Khazaeni, MD: My pleasure. Thanks for having me.

Host: Today we're going to explore, like I said, strabismus and some of the myths and misconceptions surrounding this condition. So maybe, Dr. Khazaeni, you can explain to our listeners what exactly this condition is?

Dr. Khazaeni: Strabismus is just a misalignment of the eyes. Very simply, it's a condition in which the eyes are pointing in two different directions.

Host: Got it. Are there different kinds of strabismus? Maybe someone may have one type of it or condition of it, how does that work?

Dr. Khazaeni: The two most common types of strabismus are esotropia and exotropia. Esotropia is the condition in which the eyes are crossing inwards, pointing towards the nose, and then exotropia is the condition where the eyes are drifting outwards or wandering outwards towards the ears.

Host: Now, I think a lot of people may be familiar with the condition referred to as lazy eye. Is that the same thing as this is? How does that work?

Dr. Khazaeni: Lazy eye is kind of a tricky term and that's because a lot of people use the term lazy eye to refer to an eye that's drifting outwards or an eye that doesn't see well, and that brings us to a whole new vocabulary term, which is amblyopia. Amblyopia is actually a dullness of vision or a decrease in vision. So, amblyopia refers to how well the eye is seeing whereas strabismus has to do with the position of the eye.

Host: Now let's talk about just some of the myths surrounding strabismus. I think there's a belief that strabismus is caused by too much screen time looking at your computer, looking at your phone, watching the TV too close when you were a kid. Is there any truth to this?

Dr. Khazaeni: No, unfortunately, no. I wish I could say that screen time was evil and we should all put our screens away. But we don't have any data to show that screen time or any of those things affect the development of strabismus. That being said, the American Academy of Pediatrics has some guidelines about screen time for youth and children, especially young children. So, it should be monitored, but we don't know that it affects strabismus or causes strabismus.

Host: Any thoughts that strabismus can just go away on its own if left untreated or ignored? Over the next few years as a child develops, grows, strabismus will go away? Is that accurate?

Dr. Khazaeni: That's actually a really common myth. A lot of parents might notice their child's eyes crossing or drifting and then they do think that it'll go away, and as a result, they sometimes delay treatments and don't come in to get it checked out in a timely manner. Strabismus or misalignment of the eyes, once it exists, once it's present, it's either going to stay the same or it's going to get worse. Any child who even the parents suspect may have a misalignment of the eyes really warrants an evaluation and a good examination with the pediatric ophthalmologists.

Dr. Khazaeni: One thing to be aware of is that some strabismus starts out intermittently, so it might be present one day and gone the next. If it is intermittent, it's still strabismus and it's still there, and it still should be checked out.

Host: Are there any other myths or misconceptions about childhood strabismus that you frequently encounter or questions you get very often from parents or see often in the media that you want to either debunk or kind of take care of here?

Leila M. Khazaeni, MD: One is that people think once you have strabismus surgery, the strabismus is treated and cured, and you're kind of finished. And that's not true. Strabismus is very much a lifelong process. Even after a child has one surgery for strabismus, they need to be monitored over time, even into adulthood. It's not uncommon to require a second surgery and/or glasses or other treatments down the line. That actually brings up another myth, which is that strabismus can't be treated in adults. And that's not true. There are adults who develop strabismus or misalignment of the eyes, and it's not too late for them. They can also be treated, have surgery or use other treatments to resolve the strabismus.

Host: Can adults acquire strabismus at a later age? Or is it almost always in children?

Dr. Khazaeni: Adult strabismus, there are two routes to it. One route is decompensated childhood strabismus. So, they may have had a problem as a child and had some treatments and then it either occurred or worsened as they got older. The other category is strabismus that started in adulthood, and that actually happens quite frequently, either from trauma or from injuries, cranial nerve palsies. Some other really common causes are thyroid eye disease and things like myasthenia gravis can cause strabismus, and even just the process of aging can lead to strabismus.

Host: Let's switch gears a little bit and get into some diagnosis and treatment. How is strabismus typically diagnosed?

Dr. Khazaeni: Strabismus is diagnosed during an ophthalmology exam using techniques such as the gold standard is the alternate cover test. One thing to keep in mind, this is another myth, strabismus cannot be diagnosed from a photograph. You actually have to have an examination with some specialized techniques to uncover whether the eyes are truly misaligned.

Host: Are there any new technologies to diagnose it or has the process essentially been unchanged for quite a while?

Dr. Khazaeni: The process has been pretty much unchanged for a long a long time. What has changed is the screening process, though. Children undergo vision screening at their pediatrician offices starting as early as infancy, but once they're around the age of two, three and four years old, they can undergo photo screens that uses a device, it looks like an old fashioned Polaroid camera, that's held two or three feet away from the child and it uses some infrared beams to measure whether strabismus is present, whether there's a refractive error, or whether they might need glasses. It doesn't take the place of a formal eye exam, but it can tell pediatricians who might be at risk for developing strabismus and amblyopia. That's really helped in terms of getting kids into pediatric ophthalmologists at an earlier point to get treatment early.

Host: Is there anything parents should do to prepare their child for an eye screening or anything they should expect during an eye screening to make the experience better for themselves or their child?

Dr. Khazaeni: For the eye screening at the pediatrician’s office, it's pretty harmless and pretty easy in terms of procedures that there's no hands on, it's usually done from a distance and the child can be in the parent’s lap. Once they come to the ophthalmologist office, they undergo more thorough examination, including checking visual acuity and eye pressures and the health of the eye. The big thing with an ophthalmology examination in our offices and all pediatric ophthalmology offices is that the kids need to get dilating eye drops and that's sometimes pretty tough for them. Nobody likes getting drops in their eyes, but it's an important part of the examination that's probably the biggest thing to be aware of.

Host: Now, I know you mentioned this earlier, but maybe you can get into a little bit more detail about how strabismus is treated?

Dr. Khazaeni: There are a couple of different ways to treat strabismus depending on the cause. In some forms of strabismus, glasses can be prescribed and that can help to control the strabismus and keep the eyes aligned. In other cases, surgery is required. There are even some forms of strabismus in which the combination of the two - meaning surgery and glasses - may be needed to control the strabismus over time. In adults, prism glasses can also be used to control strabismus. That's something that's not really an option for children, but it is a nice treatment for small angle strabismus in adults.

Host: What does that surgery look like, especially in children? I'm sure for a lot of parents, it can be scary getting a surgery for your child's eyes. What does that surgery typically entail?

Dr. Khazaeni: It's an outpatient surgery. It is usually under general anesthesia, but it's about an hour and a half surgery. The children and the parents come to the preoperative area about an hour or two before the surgery, and they're in recovery for an hour later, so it's a four or five hour, kind of half day, for the surgery. We usually don't put patches or bandages on the eyes and the all the surgery is done on the white part of the eye. There's really nothing on the skin and all the sutures are absorbable, but it is real surgery. A lot of people ask if it's laser surgery, and it's not. It's actual real surgery and we move the muscles, and the results are usually quite good.

Host: Why is early diagnosis and treatment of strabismus so important? I know if untreated, it can become something where it may not go away. So how important is it to identify this early and get it taken care of as soon as possible in a child?

Dr. Khazaeni: It's really critical to diagnose and treat strabismus early because if untreated, it can lead to irreversible vision loss. The visual system develops up until the age of about eight to 10 years of age. What I tell patients is once you're eight, nine, 10 years old, whatever you have vision wise, that's what you're going to have for life. You're going to take it with you unless something else happens up until that point. If strabismus is present, then the brain may kind of ignore one eye that's misaligned and not use it. There's no treatment after the age of eight or nine or 10 that will bring that vision back, so that period of visual development is really the important thing.

Host: What about any preventative measures or habits that parents can encourage in their child to reduce the risk of strabismus developing in their kids?

Dr. Khazaeni: There's really nothing specific that parents can do that will change whether or not strabismus will develop. Good eye health is just related to good health overall and a balanced diet and good activity. No amount of carrots or vitamins will help prevent strabismus.

Host: Maybe you can get into good eye health for children generally. What does that look like? What should parents do? I'm thinking of sunglasses, but I'm sure there's more than that.

Dr. Khazaeni: Sunglasses, wearing a hat if you're in bright sunlight, especially if you live in in really sunny places like I do in Southern California. Other than that, there's really nothing specific.  A lot of older adults, we use artificial tear drops to keep their eyes moist and lubricated, especially while using screens. Kids really don't like eye drops, in my experience much at all, so it's usually traumatic to put teardrops in. One thing they can do instead of teardrops, this is for elementary school age children and older who do have to use screens for school quite a bit, taking a break every 20 minutes for about 20 seconds and looking at an object 20 feet away. The 20/20/20 rule is a nice way to give the eyes a break from focusing on a screen, so that that's one good tip.

Host: Dr. Khazaeni, as we close out here, if our listeners are looking for more information about strabismus, where should they go?

Dr. Khazaeni: Be careful what you find on the Internet because there's a lot out there. Try to stick with good, trusted sources. Merck Manuals has a nice website with a lot of good information. There are a couple of ophthalmology specific websites as well. The American Academy of Pediatric Ophthalmology and Strabismus,, and American Academy of Ophthalmology,

Host: Dr. Khazaeni, thank you so much for joining us on this podcast. Certainly, a great conversation busting some of those myths surrounding strabismus. As we close it out, I'll let you leave our listeners with the final word.

Dr. Khazaeni: Medical knowledge is power. Pass it on.