Paediatr Child Health Vol 9 No 7 September 2004 471

Nowhere is there a greater discrepancy between paedia-

tricians and ophthalmologists than in differentiating

between periorbital and orbital cellulitis in children. The

former tends to be overdiagnosed while the latter is often

undertreated.

Try the true and false self-assessment questions in Table 1

before reading further.

The key to understanding these two completely different

conditions is awareness of the orbital septum, which is an

extension of the periosteum of the frontal bone (Figure 1). It

inserts into the tarsal plate of the upper lid, and infection

does not penetrate from front to back or vice versa through

this tough structure, unless it is breached by a sharp object.

Infection in front of the orbital septum causes preseptal or

periorbital cellulitis, while disease processes posterior to the

orbital septum cause post septal or orbital cellulitis.

Therefore, the etiology and treatment of these two condi-

tions is completely different.

Periorbital cellulitis usually has an obvious local cause

such as a sty or chalazion, spreading conjunctivitis or dacry-

ocystitis. The cellulitis may result from a break in the skin

such as those caused by superficial trauma, animal bites or

local infections. Patients generally will show no systemic

signs (Figure 2). There is no leukocytosis or fever, and they

appear otherwise well. There is no pain on eye movement,

vision is not impaired and there is usually no x-ray or com-

puted tomography evidence of sinusitis. The extent of the

infection does not respect the orbital septum because it is

anterior to this structure and runs freely above or below the

OPHTHALMOLOGY SUBSPECIALTY NOTE

Department of Ophthalmology, Children’s Hospital of Eastern Ontario, and University of Ottawa, Ottawa, OntarioCorrespondence and reprints: Dr William N Clarke, Department of Ophthalmology, Children’s Hospital of Eastern Ontario, and University of

Ottawa, 401 Smyth Road, Ottawa, Ontario K1H 8L1. Telephone 613-737-2574, fax 613-738-4237, e-mail clarke@cheo.on.ca

Periorbital and orbital cellulitis in children

William N Clarke MD FRCSC

TABLE 1Self-assessment questions

True False

1. On clinical examination, an ophthalmologist can distinguish

between early orbital and periorbital cellulitis. T F

2. As periorbital cellulitis worsens, it becomes an T F

orbital cellulitis.

3. Fever and leukocytosis occur commonly in both orbital

and periorbital cellulitis. T F

4. Changes in the density of orbital tissues on the computed

tomography scan are seen in orbital but not

periorbital cellulitis. T F

5. Extraocular muscle palsy and/or proptosis are helpful in

distinguishing early orbital from periorbital cellulitis. T F

6. Periorbital cellulitis rarely has an obvious external cause T F

7. Reduced visual acuity is helpful in distinguishing periorbital

from early orbital cellulitis. T F

8. The bulbar conjunctiva (globe) is injected in orbital cellulitis

but rarely in periorbital cellulitis. T F

The answers are at the end of this article

Figure 1) Insertion of the orbital septum into the tarsal plate of theupper lid

Figure 2) Periorbital cellulitis secondary to infected chicken pox

Clarke-cellulitis.qxd 02/09/2004 3:57 PM Page 471

orbital rim. Treatment is directed toward the local cause of

the infection (ie, treatment of conjunctivitis, chalazion or

herpetic blepharitis). On rare occasions, systemic antibi-

otics are indicated for a particularly severe inflammation,

but they generally are not required.

Patients with orbital cellulitis are irritable, toxic and

have a fever. They have erythema and induration of one or

both lids, often respecting the orbital septum with signifi-

cant pain on pressure over the lid. The globe may be injected

and there may be pain on eye movement. Late signs include

limitation of extraocular movement, proptosis, decreased

visual acuity and papilledema. An increased white blood cell

count and x-ray and computed tomography evidence of uni-

lateral or bilateral sinusitis, particularly involving the adja-

cent sinus, are likely to be present (Figure 3).

The etiology of orbital cellulitis is related to the ethmoid

bone (lamina papyracea), which is paper thin, separating

the sinus from the orbit. Infection spreads from the sinus

into the adjacent orbit but lies under the periosteum where

it may collect as a subperiosteal abscess, causing exotropia,

proptosis and restriction of eye movement nasally (Figure 4).

All these signs occur late and are not helpful in distinguish-

ing orbital from periorbital cellulitis early on.

Treatment of orbital cellulitis consists of admission to

the hospital and intravenous antibiotics, currently cefurox-

ime axetil and clindamycin hydrocloride. These drugs take

effect in 12 h to 36 h; therefore, worsening of the condition

on day 1 is not a source of concern. Subperiosteal abscesses

usually respond to intravenous antibiotics, but if it is large,

it may need to be drained surgically. Subperiosteal abscesses

located superior to the globe must always be drained

surgically.

After recovery, oral antibiotics such as Keflex (Biocraft

Laboratories Inc, USA) are indicated for 10 to 14 days to

clear any residual sinusitis. Nasal decongestants and follow-up

with an otolaryngologist to ensure resolution of the sinusitis

are indicated.

In summary, consider the four factors differentiating

periorbital from orbital sinusitis in Table 2.

Paediatr Child Health Vol 9 No 7 September 2004472

Ophthalmology Note

Figure 3) Ethmoid sinusitis (arrow)

Figure 4) Exotropia and proptosis secondary to subperiosteal abscess

TABLE 2Factors differentiating periorbital from orbital sinusitis

Periorbital cellulitis Orbital cellulitis

Obvious external cause Yes No

Fever No Yes

Leukocytosis No Yes

Ethmoid sinusitis No Yes

All statements in Table 1 are false.

Clarke-cellulitis.qxd 30/08/2004 1:43 PM Page 472