All Eyes on Me
Author: Dr. Vanessa Graff
Background: You are stalking the ED trackboard and you see that your next patient coming to you has a chief complaint of “eye pain.” You immediately grunt. Eye pain and rash, our two favorite chief complaints, am I right?! Well, let me help make it more interesting for you! Let’s have fun with putting a HUGE amount of ultrasound gel on your patient’s eye and being able to diagnose important pathology! Things that you can quickly and easily diagnose with ocular ultrasound include (but not limited to): retinal detachment, globe rupture, foreign body, dilated optic nerve sheath, and vitreous hemorrhage. WOW, that’s so many things with a quick and easy exam! See, now we don’t have to grunt when we see “eye pain” coming our way!
In order to understand what we are seeing with the ultrasound, we need to quickly review our eye anatomy. Let’s highlight some very important structures. The cornea is the dome-shaped surface on the front of the eye that helps us focus light. The fovea helps us sharpen our vision and the iris regulates how much light enters the eye. The optic nerve connects the eye to the brain’s visual cortex and without it, you would be blind. Make note of the location of the retina, another important structure. It is a nerve layer that is located in the back of the eye.
For the ultrasound, you want to use the linear probe and as mentioned above, you want to use A LOT of ultrasound gel. The normal eye appears as a circular hypoechoic structure. The cornea is a thin hypoechoic layer that is parallel to the eyelid. It is important to note that the normal retina cannot be differentiated from the other choroidal layers. Here is what you will see on ultrasound without any abnormalities:
Retinal detachment: If your patient is complaining of loss of vision described as “curtain coming down” over the eye, flashing lights, floaters, and has a history of Diabetes Mellitus, your spidey sense should immediately be thinking of retinal detachment. Luckily, we are able to diagnose this with ultrasound so we sound extra smart when we consult our ophthalmologist friends. Don’t forget this is a true emergency and we should be getting optho on board as soon as we suspect it. Once you call them and are waiting for them to come down, grab that ultrasound and this is what you are looking for: a hyperechoic undulating membrane in the posterior lateral globe.
Globe rupture: Now let’s say your patient has had trauma to their eye and presents with a teardrop pupil and/or subconjunctival hemorrhage. Globe rupture should ALWAYS be on your differential and there are a couple diagnostic tests up our sleeves. You can do fluorescein testing which would show you the positive Siedel’s test which is the leak of aqueous fluid from the globe penetration. You can also grab your ultrasound which will show you decreased globe size, anterior chamber collapse, and buckling of the sclera. This is always an emergency and we need to get optho on board ASAP.
Foreign body: Different scenario: your patient was being naughty and cutting metal or wood at home without safety glasses. Or they were outside and it was extremely windy and they felt like something flew into their eye. They come into the ED complaining of eye pain and a sensation of a foreign body in their eye. In addition to fluorescein testing (with flipping the eyelid to always evaluate for a retained foreign body), we can also use bedside ultrasound! On ultrasound, you will see a hyperechoic structure with shadowing.
Dilated optic nerve sheath: This would be a sign of increased intracranial pressure. A normal optic nerve sheath measures up to 5.0mm in diameter. You want to measure the optic nerve 3mm posterior to the globe as this is when the ultrasound contrast is greatest. If your optic nerve sheath is measuring greater than 5.0mm, you should consider increased ICP
Vitreous hemorrhage: Your patient is complaining of a “visual haze,” floaters, cloudy vision, photophobia, and perception of shadows or cobwebs. This should make you concerned for possible posterior vitreous hemorrhage. Your bedside ultrasound is a very useful tool and will show a visible swirl.
Hopefully this helps and makes “eye pain” a little less terrifying and a little more fun on your next shift!