**5. Sources of infection**

may be swollen along with conjunctival chemosis as well as some degree of proptosis. Visual loss may be present in Group II patients. Purulent material may be collecting as subperiosteal abscess between the periorbita and the bony walls of the orbit in Group III. These patients may have significant conjunctival chemosis, eyelid edema, along with tenderness in the involved areas with variable degree of proptosis, and decreased ocular motility. The abscess may be anywhere in the vicinity of the orbit. Patients in group IV (orbital abscess), may present with their abscess being inside or outside the muscle cone following untreated orbital cellulitis. These patients may have significantly more pain, proptosis, decreased ocular motility and variable degree of severe visual loss. Patients in group V may present with bilateral eyelid edema along with involvement of third, fifth and sixth cranial nerves which is thought to be due to the extension of the infectious process into the cavernous sinus with formation of thrombosis. These patients may have nausea, vomiting along with signs of nervous system involvement which could also be due to septicemia. Signs of proptosis, eyelid edema, optic neuritis, frozen globe, decreased supra-orbital nerve conduction may be hallmarks of orbital apex syndrome which is thought to be due to the sinusitis in the area of the superior orbital

**Figure 3.** External photographs of a young male child who suffered trauma over his right brow area after which he

Our own experience in treating orbital cellulitis from a developing country confirmed previous observations from the Western countries in which sinusitis has been implicated as the cause of orbital cellulitis in most of the cases. [8] Specifically in children, vast majority of cases with orbital cellulitis had pre-existing sinusitis, and significant number of them had multiple sinuses involved. Our experience revealed that unlike patients from the Western countries, most patients with sinusitis and orbital cellulitis in the developing countries had sought treatment later in the course of their disease. Unlike Western countries, in our patients, prior history of periocular trauma or ocular/ periocular surgery were also very common cause of orbital cellulitis. (Figure 3). [1], [10] Although less common, dacryocystitis, dental infection and endophthalmitis, were also found to be the cause of orbital cellulitis in our patients (Figure 4). [8] Patients with prior history of sinusitis may also develop osteomyelitis and intracranial infection. In these cases, osteomyelitis, commonly involve the frontal bone which is due to a direct extension of frontal infection or septic thrombophlebitis via the valveless sinus of

developed orbital cellulitis and formation of an abscess that required drainage.

fissure and optic foramen. [14]

126 Common Eye Infections

Usually, orbital cellulitis occurs in the childhood years which has been attributed to the relatively incomplete development of immunity in this age group. [1], [4], [5], [16], [17] In these patients, sinus disease has been found to be the most common predisposing factor. Over 90% of these patients have radiologically confirmed sinusitis, the most common being ethmoidal and maxillary. [1], [8] In the reported series, ethmoidal sinusitis has been demonstrated to be the source of infection in significantly large number of cases. [18], [19]

Ethmoidal sinusitis is usually present with maxillary sinusitis on the same side of the infection. [19], [20] Frontal sinus disease has been frequently identified especially in series in which a large number of adolescents and adults have been studied (Figure 5). [10], [18], [20] Up to 38% of children may have more than one sinus involved and in the adult patients, up to 50% may have underlying sinusitis, while up to 11% may have multiple sinuses involved. [1], [8] Other etiological factors resulting in orbital cellulitis may include dacryocystitis with orbital exten‐ sion (Figure 6), retained foreign body, panophthalmitis, infected tumor, Herpes Zoster, (Figure 7), and mucormycosis. [8], [21]

As orbital cellulitis has a close relationship with sinus (Figure 5), and upper respiratory disease, a seasonal distribution paralleling that of upper respiratory infections (URI) has been docu‐ mented with a bi-model seasonal distribution of cases with peak occurring in late winter and early spring season. [1], [8] Bacterial sinusitis can result in orbital cellulitis leading to a subperiosteal abscess from the accumulation of purulent material between the periorbita and the orbital bones. [6], [8], [20] Since the use of modern imaging studies in the form of computed tomography (CT-scan), the concept of subperiosteal abscess has been accepted as a separate

**Figure 5.** Anterior and sagittal view of the frontal, ehtmoidal, sphenoid and maxillary sinuses and their close relation‐ ship with orbital anatomy.

**Figure 6.** External photograph of a 42-years-old female who presented with left-sided orbital cellulitis and abscess formation due to the acute over chronic dacryocystitis.

entity. [20], [22] Because of the reports of rapidly progressive visual and intracranial compli‐ cations from subperiosteal abscess, some clinicians argue for the prompt surgical drainage of the abscess and paranasal sinuses when a subperiosteal abscess is first diagnosed by a CT-scan. [15], [20], [22-26] Among our survey of 218 patients who required treatment of their orbital cellulitis, imaging studies revealed that sinus disease was the most cause in 39.4%, trauma in 19.7%, endophthalmitis in 13.3%, (Figure 8), orbital implants in 8.2%, dacryocystitis in 4.6%, retained orbital foreign body in 3.2%, dental infection in 2.7%, and scleral buckle in 2.3%.8 A history of sinusitis and recent trauma was the cause of orbital cellulitis in 4.1%, and intraocular or orbital tumors were the cause in another 4% of patients.

**Figure 7.** External photograph of a 19-years-old male who presented with 3 day history of left-sided facial erythema, swelling, conjunctival chemosis, proptosis and eruptive skin lesions. A diagnosis of Herpes Zoster Ophthalmicus was made and patient was treated for acute Zoster infection and its complications.

In diabetic and immune-compromised patients one has to rule out fungal infection as the cause of orbital cellulitis, the most common being Mucormycosis and Aspergillosis. While infection with Mucormycosis has no climatic or age restriction, Aspergillosis usually occurs in hot and humid climates in patients older than 20 years of age. Although predisposing factors for Aspergillosis are unclear multiple risk factors for Mucormycosis have been proposed, among them diabetic ketoacidosis is the most common. The course of onset for Mucromycosis infection is rapid (usually 1-7 days) as compared with slow infection due to Aspergillosis which can take a month to a year. Otolaryngologic findings in patients with Mucormycosis may include nasal and palatal necrosis along with paranasal sinusitis. In Aspergillosis, one may find evidence of chronic fibrosis and non-necrotizing granulomatous reaction of the involved structures. In cases of Mucromycosis infections there is evidence of ischemic necrosis along with thrombosed arteries

entity. [20], [22] Because of the reports of rapidly progressive visual and intracranial compli‐ cations from subperiosteal abscess, some clinicians argue for the prompt surgical drainage of the abscess and paranasal sinuses when a subperiosteal abscess is first diagnosed by a CT-scan. [15], [20], [22-26] Among our survey of 218 patients who required treatment of their orbital cellulitis, imaging studies revealed that sinus disease was the most cause in 39.4%, trauma in 19.7%, endophthalmitis in 13.3%, (Figure 8), orbital implants in 8.2%, dacryocystitis in 4.6%, retained orbital foreign body in 3.2%, dental infection in 2.7%, and scleral buckle in 2.3%.8

**Figure 6.** External photograph of a 42-years-old female who presented with left-sided orbital cellulitis and abscess

**Figure 5.** Anterior and sagittal view of the frontal, ehtmoidal, sphenoid and maxillary sinuses and their close relation‐

history of sinusitis and recent trauma was the cause of orbital cellulitis in 4.1%, and intraocular

or orbital tumors were the cause in another 4% of patients.

formation due to the acute over chronic dacryocystitis.

ship with orbital anatomy.

128 Common Eye Infections

A

**Figure 8.** External photographs and U/S of the right eye of a 73-years-old male who developed panophthalmitis after cataract surgery.
