PC usually presents itself with a mild to moderate temperature increase, generally associated with leukocytosis and mild febrile response. Patients frequently complain of the general inflammatory signs, like pain, swelling and redness, which can be coupled with more specific ones like epiphora and blurred vision. The edema might sometime be so pronounced to impede the voluntary closure of the eye.
Together with the general eyelid inflammation, a limited eye mobility can be also observed, usually accompanied by impaired vision, which is suggestive of a spread of the inflammatory state to the orbit. Moreover, since PC frequently originates from an upper airways inflammation, pathological conditions such as tenderness, rhinorrhea, and adenopathy  usually indicate its development.
Given that PC is very similar to orbital cellulitis, which is an emergency state that requires immediate treatment, it is extremely important to remember the major signs to differentiate the two. These include bulging (proptosis), limited eye movement (ophthalmoplegia), pain on eye movement itself and loss of vision, which are always observed in orbital cellulitis but not in PC.
The workup of PC might include blood cultures, even though just in the cases in which sepsis is suspected. White blood cells (WBC) are generally elevated, usually varying from 14000 and 20000 cells/µL according to the presence of bacteremia, but unfortunately this is not sufficient to differentiate PC from the closely related orbital cellulitis.
Conversely, imaging studies are helpful, and should be employed when pain on eye movement, afferent papillary defect, limited extraocular motion, and resistance on repulsion are observed. Particularly used is CT scan, which is not necessary in all patients but can allow to delineate the extent of the orbital region effected by the infection  . A valid alternative to CT scan is orbital ultrasonography, which helps to diagnose the orbital inflammation quickly and effectively, provided that experienced observers and specialized equipment are available.
The serious ocular and CNS complications have markedly reduced over the last a few decades, due to the availability of earlier diagnosis, expeditious treatment and increasingly more effective antibiotics, in a treatment that is now focused on close observation, antibiotic therapy, and the management of predisposing conditions like sinusitis .
The antibiotic choice has to be carefully evaluated to take into consideration the already mentioned predisposing factors. It can be integrated with surgical drainage of the area affected, but this just in the cases of eyelid abscesses  and only when PC appears to have no complications.
In the cases in which the eye cannot be evaluated or physicians suspect the spread of the infection from nearby areas, consultations from other specialists should be considered. In particular, ophthalmic consultation is recommended for all pediatric patients , otorhinolaryngology consultation for the medical and surgical treatment of sinusitis and when a fungal infection is suspected, while infectious disease consultation is recommended in the clinical cases that do not properly respond to a standard treatment.
If the patients effectively respond to empiric antibiotics and can take oral antibiotics, outpatient care might be seriously contemplated. In particular, the outpatient follow-up care should be based on the evaluation of signs of relapse, such as fever, erythema, edema, and vision loss.
There are several antibiotics indicated for the PC treatment. These include amoxicillin/clavulanic acid or intramuscular ceftriaxone, just for outpatient treatment and only for selected patients, second- or third-generation cephalosporins, particularly recommended for initial empiric therapy, and penicillinase-resistant synthetic penicillin, like nafcillin or oxacillin, which are indicated when an infection from Staphylococcus aureus is suspected.
The prognosis of PC is generally excellent, with no related complications if promptly identified and properly addressed with the right treatment. However, its seriousness should never be underestimated, as PC might threaten vision and spread into the central nervous system (CNS), with all the devastating consequences of the case. For example, its development can set up a systemic spread of bacteria towards the nervous system which might end up triggering meningitis and even sepsis.
According to a study made on a pediatric population affected by intracranial infections, the high-risk features of PC  include the age older than 7 years, subperiosteal abscess, and persisting headache/fever  even under treatment of intravenous antibiotics. Fungal infections are the most important risk factors, as they can rapidly become fatal especially in immunecompromised or diabetics subjects.
Periorbital cellulitis is a bacterial infection which originates from a nearby inflammatory process, where the microorganisms literally move from the original site to the eye. This can happen when the right conditions are present, which include the presence of a way through which the bacteria can reach the orbital region, such a scratch or a insect bite. Once arrived at the eye, the microorganisms enter the tissues underneath the skin and cause the infection. Usually, bacteria come from a sinus infection or a condition of the upper respiratory tract, and this is the reason why PC is generally triggered by sinusitis.
The most common species of bacteria responsible for causing PC include Staphylococcus, Streptococcus, and especially Haemophilus influenzae, the most common of the three. The incidence of this infection is greatly decreased since 1990, after the introduction of Haemophilus influenzae type B (HIB) vaccine  .
To date, no racial or gender predilection has been reported in adults affected by PC. However, as already mentioned, PC is much more frequent in children than in adults, and among the former males have a probability to get PC which is almost twice as high as that of females . Furthermore, PC is far more frequent during winter months, due to the increased risk in this period of sinusitis, which as previously seen is deeply connected to PC itself as an indirect source of bacteria.
Before the development of the HIB vaccination, which is now used as routine clinical tool to treat the disease, the incidence of PC was reported to be as high as 80% , but now it is extremely rare.
Periorbital cellulitis is usually the “side effect” of another infection occurring near the orbit region, which has to be seen as a predisposing factor preparing the conditions for the occurrence of PC itself. From these infected spots the bacteria start moving towards the eyelid, using a way which is generally a scratch, a wound, or a bite. The most important predisposing factors are undoubtedly sinusitis, infections of the upper respiratory tract or other external ocular infections, to which must be added secondary ones such as acne, eczema, or periocular surgery.
One of the most effective measures to prevent PC is HIB vaccination. This prophylactic strategy should be integrated with other preventive actions, such as promptly treating any injury in the region around the eye, from which a pathogen might come to infect the ocular area, or avoiding swimming when an injury in the ocular area is present. Early treatment of sinus infection is also highly recommended, to avoid any progression towards the development of periorbital and orbital cellulitis.
Although very serious as inflammation, periorbital cellulitis (PC) is quite treatable if the clinical procedures are correctly followed. The inflammation generally provokes eyelid erythema and edema, but rarely causes pain, which is usually replaced by a persistent discomfort constantly annoying the patients. As a rule, PC involves just one eye and never travels to the other one, which means the discomfort is restricted to the region of the eye affected. The disease is very common among children younger than 6 years of age, and rare in adults.
Periorbital cellulitis (PC) is a bacterial infection affecting the eyelids and the adjacent regions of the skin, usually caused by the spread of nearby infections such a conjunctivitis or sinusitis. The inflammation causes redness and swelling of the eye and the surrounding regions of the skin, but rarely causes pain. As a rule, PC involves just one eye and never travels to the other one, which means the discomfort is restricted to the region of the eye affected.
With the occurrence of the right conditions, the microorganisms responsible for a nearby infection can literally move from the original site to the area of the eye. This occurs through the a way, which is often a scratch or a insect bite. Once arrived at the eye, the microorganisms find a wound to enter the tissues underneath the skin and cause the infection.
PC usually presents with a mild to moderate fever and general inflammatory signs, like pain, swelling and redness, which can be coupled with tearing and blurred vision. Together with the general inflammation, a limited eye mobility can be also observed, usually accompanied by impaired vision.
The prognosis of PC is generally excellent, with no related complication if promptly identified and properly addressed with the right treatment. However, its seriousness should not be underestimated, as PC might threaten vision and spread into the central nervous system (CNS).
There are several antibiotics indicated for the PC treatment. These include amoxicillin/clavulanic acid, ceftriaxone, and second- or third-generation cephalosporins. To prevent PC it is very important to promptly treat any injury in the region around the eye, from which a pathogen might come to infect the ocular area, and avoid swimming when an injury in the ocular area is present. Early treatment of sinus infection is also highly recommended, to impede any progression towards the development of periorbital and orbital cellulitis.