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Q: CT-Scan for Ocular Injury ( Answered 5 out of 5 stars,   2 Comments )
Subject: CT-Scan for Ocular Injury
Category: Health > Conditions and Diseases
Asked by: mdgrimes-ga
List Price: $10.00
Posted: 18 Apr 2002 23:21 PDT
Expires: 25 Apr 2002 23:21 PDT
Question ID: 2014
My question relates to the advisability of a CT-Scan for an eye injury 

My son was injured this past Saturday in a little league baseball game when a 
ground ball hit hard took a bad bounce and hit him in the eye.  The impact was 
fierce and knocked him to his feet.  By the time he got to the emergency room 
15 minutes later, the eye had swollen shut, but before that it looked like the 
severity was concentrated a quarter inch or so below the eye.  The physician in 
the emergency room checked him out and said that he did not appear to have any 
serious damage and did not recommend an X-ray or CT-Scan, only that we have his 
eye motion checked after the eye opened up in a few days.  A doctor who was in 
the stands at the baseball game said that he would get a CT-Scan if it were his 
kid, because you can never be too sure when dealing with the eye. 

So my question is -- is there any reason not to do a CT-Scan in this 
situation?  Also any information on whether it is costly and are there side 
effects would be appreciated, as well as how soon would it need to be done if 
it does make sense.
Subject: Re: CT-Scan for Ocular Injury
Answered By: gale-ga on 19 Apr 2002 11:42 PDT
Rated:5 out of 5 stars

Yes, it looks like there are reasons not to do a CT scan in this case. CT 
(computed tomography) scanning uses x-rays, and sometimes causes severe side 
effects, especially in children. MRI (magnetic resonance imaging) is a safer, 
but more expensive procedure. CT scans are most effective during the 48-72 
hours after a trauma. MRI scans are more effective later (during the post-acute 

The section on Black Eye from the National Center of Emergency Medicine 
Informatics does not recommend getting x-rays if there are "no palpable 
"The patient has received blunt trauma to the eye, most often from a fist, a 
fall, or a car accident, and is alarmed because of the swelling and 
discoloration. Family or friends may be more concerned than the patient about 
the appearance of the eye. There may be an associated subconjunctival 
hemorrhage, but the remainder of the eye exam should be negative and there 
should be no palpable bony deformities, diplopia or subcutaneous emphysema. 

What not to do:
Do not get unnecessary radiographs. Minor injuries with normal eye exams and no 
palpable deformities do not require x rays. 
Do not brush off bilateral deep periorbital ecchymoses ("raccoon eyes") 
especially if caused by head trauma remote to the eye. This may be the only 
sign of a basilar skull fracture.
Black eyes are most commonly nothing more than uncomplicated facial contusions. 
Patients become upset about them because they are so "near the eye," because 
they produce such noticeable facial disfigurement, and because there is often 
secondary gain being sought against the person who hit them. Nonetheless, 
serious injury must always be considered and ruled out prior to the patient's 
discharge from your care."

If you search MedLine (, e.g., 

tomography [mh] AND eye [mh] AND injury AND human [mh]
tomography [mh] AND eye [mh] AND "radiation protection" [mh] AND human [mh]

you will find some articles that emphasize the risks of CT scanning for 
children, e.g.:

AJNR Am J Neuroradiol 2001 Jun-Jul;22(6):1194-8
Radioprotection to the eye during CT scanning.
Hopper KD, Neuman JD, King SH, Kunselman AR.
Department of Radiology, Penn State University, Hershey, PA 17033, USA.

"BACKGROUND AND PURPOSE: The lens of the eye is sensitive to radiation. 
Children undergoing CT of the head and patients undergoing repeated CT scanning 
of the head are vulnerable to this complication."

Neuroradiology 1982;22(4):181-4
Irradiation dose to the lens of the eye during CT of the head.
Lund E, Halaburt H.

"The irradiation dose to the lens of the eye during CT scanning has been 
measured in 16 patients. The dose is greatly influenced by changes in gantry 
angulation, the position of the patient, the thickness and number of 
slices, KV, and milliamperage. The total lens dose has been measured to be 
higher than previously reported. 

Repeated CT scans imply the risk of irradiation cataract, especially in infants 
and children."

If you go to an ophthalmologist, read up on different diagnostic techniques.

MRI and CT scanning are two most popular imaging techniques used for examining 
soft tissues of the head. CT scan uses x-rays, and MRI uses radio waves and a 
strong magnetic field to obtain images of the head. MRI has fewer side 
effects. MRI is more expensive than CT scanning, and CT scanning is more 
expensive than regular x-rays.

You will find some detailed and authoritative information about different 
diagnostic techniques on the National Library of Medicine website; they provide 
a section on Diagnostic Imaging on their Medline Plus site:

There are links on that page to some information about MRI and CT scans of the 
head on the Radiological Society of North America website, outlining risks vs. 
benefits of each procedure:

CT scan of the head

"What is CT Scanning of the Head?
CT (computed tomography), sometimes called CAT scan, uses special x-ray 
equipment to obtain many images from different angles, and then join them 
together to show a cross-section of body tissues and organs. CT scanning 
provides more detailed information on head injuries, brain tumors, and other 
brain diseases than do regular radiographs (plain films). It also can show 
bone, soft tissues, and blood vessels in the same images. CT of the 
head and brain is a patient-friendly exam that involves little radiation 
 What are the benefits vs. risks?
 CT of the head is now widely available and is performed in a relatively short 
time and at a reasonable cost - especially when compared to MR imaging. 
 The exam shows changes in bone better than any other imaging method.  
 It is the only method that provides detailed images of bone, soft tissue, and 
blood vessels.  
 CT is becoming the method of choice for rapidly screening trauma victims to 
detect internal bleeding or other life- threatening conditions. 

 CT does involve exposure to radiation in the form of x-rays, but the benefit 
of an accurate diagnosis far outweighs the risk. The typical radiation dose 
from a CT exam of the head and brain is equivalent to the amount of natural 
background radiation received over a year's time. Among all radiological 
procedures, radiation exposure from CT of the head is intermediate.  
Special care is taken during x-ray examinations to ensure maximum safety for 
the patient by shielding the abdomen and pelvis with a lead apron, with the 
exception of those examinations in which the abdomen and pelvis are being 
imaged. Women should always inform their doctor or x-ray technologist if there 
is any possibility that they are pregnant. 
Nursing mothers should wait for 24 hours after contrast injection before 
resuming breast feeding.  
The risk of serious allergic reaction to iodine-containing contrast material is 
rare, and CT units are well equipped to deal with them.    
What are the limitations of CT Scanning of the Head?
Compared to MR imaging, the precise details of soft tissue (including some deep 
parts of the brain) are less visible on CT scans. CT is not sensitive in 
detecting inflammation of the meninges -- the membranes covering the 

MRI of the head

"What is MR Imaging (MRI) of the Head?
MRI (magnetic resonance imaging) uses radio waves and a strong magnetic field 
rather than x-rays to provide remarkably clear and detailed pictures of 
internal organs and tissues. This technique has proved very helpful to 
radiologists in diagnosing tumors of the brain as well as disorders of the eyes 
and the inner ear. It requires specialized equipment and expertise and allows 
evaluation of some body structures that may not be as visible with 
other imaging methods.  
What are the benefits vs. risks?
 Images of the brain and other head structures are clearer and more detailed 
than with other imaging methods. 
 MRI contrast material is less likely to produce an allergic reaction than the 
iodine-based materials used for conventional x-rays and CT scanning. 
 Exposure to radiation is avoided. 
 MRI enables the detection of abnormalities that might be obscured by bone 
tissue with other imaging methods. 
 A variant called MRI angiography provides detailed images of blood vessels in 
the brain without the need to inject contrast material. 
 New MRI systems can depict brain function, and in this way detect a stroke at 
a very early stage. 

 An undetected metal implant may be affected by the strong magnetic field. 
 MRI is generally avoided in the first 12 weeks of pregnancy. Doctors usually 
use other methods of imaging, such as ultrasound, on pregnant women, unless 
there is a strong medical reason.    
What are the limitations of MRI of the Head?
Bone is better imaged by conventional x-rays, and CT is preferred for patients 
with severe bleeding. MRI may not always distinguish between tumor tissue and 
edema fluid, and does not detect calcium when this is present within a tumor. 
In most cases the exam is safe for patients with metal implants, with the 
exception of a few types of implants, so patients should inform the technician 
of an implant prior to the test. The exam must be used cautiously in early 
pregnancy. MRI often costs more than CT scanning." 

There's a discussion of different imaging methods on the Listen Up site, which 
includes a review of MRI risks.

Listen Up
"Question:  Is MRI dangerous? 

Answer:  Not usually.....There are some people that should not have an MRI.  
Top of the list are folks that have cochlear implants or pacemakers.  People 
with metal fragments in their eyes or aneurysm clips implanted in their 
brain should also avoid MRI examinations.  The strong magnetic fields can 
dislodge metal objects that are in the body.  Even worse they can overload 
implanted electronic devices and render them useless.  Always tell your 
physician and the technologist if you have implanted medical devices before you 
enter the magnet suite. 

How soon does it make sense to do a CT or MRI scan?

"The initial CT scan appearance often underestimates the actual brain injury 
and the patients clinical condition may be much worse than the CT scan would 
suggest. Diffuse injury evloves and becomes more prominent on CT during 
the next 48-72 hours after injury."

Center for Neuro Skills' Traumatic Brain Injury Resource Guide
"CT (computerized tomography): In the emergency department, CT is primarily 
used to evaluate acute TBI. CT scans detect acute hematomas and other areas of 

MRI (magnetic resonance image): This tool provides greater definition of 
lesions than the CT scan. Cellular density as well as water diffusion and blood 
perfusion is assessed. MRI is the best tool to evaluate neurological changes in 
the post-acute phase of recovery."

Also try these Google searches:

eye OR ophthalmic ct OR imaging
eye OR ophthalmic injury OR trauma diagnosis OR diagnostic
mdgrimes-ga rated this answer:5 out of 5 stars
Very thorough and responsive.  Thank you.

Subject: Re: CT-Scan for Ocular Injury
From: wwinter-ga on 19 Apr 2002 09:11 PDT
A Computed Tomography Scan (CT-Scan) is simply a very fancy type of X-ray which 
generates a 3D image instead of a 2D projection image which is what you get 
from an X-ray.  Like an X-ray, CT is best for looking at hard structures like 
bones and foreign objects.  CT side effects are identical to X-ray side effects.

Magnetic Resonance Imaging (MRI) will also generate 3D images.  MRI is best for 
looking at soft tissues like eyes and brains and has no known side effects.

Costwise, X-ray is cheapest, CT is more expensive and MR is the most expensive has a page on CT-Scans, (
TestID=8) and I really like their last comment, 
"Whether a CT, or MRI scan, is best for any given situation is best left up to 
the treating ophthalmologist and radiologist."

"An ophthalmologist is a physician (doctor of medicine, M.D., or doctor of 
osteopathy, D.O.) who specializes in the medical and surgical care of the eyes 
and visual system and in the prevention of eye disease and injury."
Taken from the Medem website

It might be a good idea to arm yourself with some information regarding the 
different types of imaging technology, then take your son to see an 
ophthalmologist.  To find one in the US, try:

For in depth information on CT and MR technology, check out
Subject: Re: CT-Scan for Ocular Injury
From: sgopal3-ga on 26 Jun 2002 13:45 PDT
It sounds as if the ER physician didn't do a CT scan for two main

1) The swelling and likely damage was below the eyeball itself. In
this case you can feel a facial fracture by just feeling the bone
under the eye.

2) Your son did not lose consciousness -- this is the most common
reason why ER physicians order CT scans -- too see if there was any
hemorrhage inside the brain. This is unlikely if your son didn't pass

Hope this helps.

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