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1. What is the difference between iritis and conjunctivitis?
Uveitis is inflammation of one or all parts of the uveal tract,
including the iris, the ciliary body, and the choroid. So iritis
is a Uveitis, but confined to the iris. To distinguish iritis
from conjunctivitis, notice where the conjunctiva is most red. In
iritis, the conjunctiva is most red at the border of the iris
(peri-limbis), compared to conjunctivitis, where the conjunctiva is
most red everywhere else but the limbis. (1)
Additionally, consensual photophobia (pain in the affected eye occurs
when light is shown into the unaffected eye) occurs in iritis and not
On slit lamp exam, if the patient has iritis, you may notice floaters
in the anterior chamber (which represent WBC floating in the
fluid). Some describe this as ‘dust in a sunlit room,’ and this
is called flair.
On slit lamp exam you may also notice precipitates (WBC) on the endothelium, which is a hallmark of iritis.
In 50% of cases, the cause of the iritis is unknown (1). Other
causes include trauma, inflammatory diseases (inflammatory bowel
disease, reactive arthritis, ankylosing spondylitis) or infectious
(herpes, toxoplasmosis, Lyme disease). (1)
The treatment is very different for these, that is why it’s important to distinguish them.
Conjunctivitis is usually treated with topical antibiotics (if
bacterial or possibly bacterial), but patients with iritis need an
ophthalmologist referral. Complications from iritis
include increased intraocular pressure (with subsequent damage to the
optic nerve if not treated) from posterior synechiae. (1).
Most cases of conjunctivitis are self-limiting, but if the patient is
immunocompromised, the condition could progress to sight-threatening
A few things to remember about conjunctivitis:
1. In the neonate, consider Neisseria gonorrhoeae. This type of
infection can be invasive and can lead to rapid corneal
perforation. (2, 3) This is much less common in the US with
topical antibiotic treatment at birth. It usually occurs on days
3-5 after birth.
2. Chlamydial conjunctivitis can also occur in neonates. It can also be
associated with pneumonia (even up to 6 months after their
conjunctivitis). (3) Again, this is not common in the
US. The incubation period for Chlamydial conjunctivitis is 5-14
3. Neonatal Herpes conjunctivitis usually occurs in the first 2 weeks after birth. (3)
4. Trachoma infection is a chronic insidious Chlamydia Trachomatis
infection. It actually is the leading cause of blindness in the
world, blinding 10% of those infected. (2)
You need to ask about contacts. Corneal abrasions are common when
a patient sleeps with contact lens in, and college kids are likely to
do this when they are either too tired from studying or partying to
bother to take the contacts out. The reason this is important is
that if the corneal abrasion is related to a contact lens, the organism
is more likely Pseudomonas.
The other question to ask is whether the visual acuity was taken with
her glasses on. Visual acuity testing in the ED is designed to
determine if there is a new decrease in the ability of the patient to
see. To test visual acuity in a patient with poor vision, without
their glasses on, is challenging to interpret. I usually test the
vision with the glasses on (I want to know if the vision has acutely
decreased). If the photophobia is causing too much pain, I try
checking visual acuity after applying a topical anesthetic. If
the patient doesn’t have their glasses with them, you can try using a
pin hole. Either way, it’s important to look for an acute
decrease in vision, not if the patient has bad vision at baseline (i.e.
find out if the baseline vision has gotten worse, not if the patient
just needs glasses).
3. What is the difference between corneal abrasion and cornea ulcer?
Both can cause pain, red eye, and photophobia. And both will
appear as a red eye with significant limbic flush (due to irritation of
A corneal abrasion is a very superficial defect in the cornea. A
corneal ulcer is a much deeper injury and infection. Sometimes you may
see the corneal ulcer even before staining. The infection can be
from a bacterial source or viral (herpes—which usually causes dendritic
staining (see pictures).
Bacterial Ulcer. Note the limbic flush.
Viral Ulcer (Herpes). Note the dendritic staining pattern.
In corneal ulcers, you may also see a hypopyon (a layering of WBC in the anterior chamber).
Herpes simplex virus is the most common cause of corneal ulcer in the
US. (4) Bacterial causes in the US include staphylococcal
infection, Pseudomonas Aeruginosa, Streptococcus pneumonia, and
Moraxella. (4) Pseudomonas Aeruginosa infections may have a
bluish or green mucopurulent discharge.
Treatment for a corneal ulcer involves consultation with an
ophthalmologist and antibiotics. Treatment for a corneal abrasion
involves topical antibiotics. Topical non-steroidal
anti-inflammatory drugs have been shown in Meta analysis to be
effective pain medications to administer. (5). Eye
patches have not been shown to improve outcome and are not recommended.
(5). For patients with corneal abrasions related to contact lens
wear, consideration for possible pseudomonas infection and treatment
with antibiotics to treat this infection should be used (ciprofloxacin,
gentamicin, tobramycin, ect.). (5) Its important to remind the
patient NOT to wear the contact lens until they have been re-evaluated
by the ophthalmologist.