Orbital lymphoma is a common type of non-Hodgkin lymphoma that occurs near or on the eye. Common symptoms include decreased vision and uveitis. Orbital lymphoma can be diagnosed via a biopsy of the eye and is usually treated with radiotherapy or in combination with chemotherapy. Types
There are two main types of intraocular lymphomas: primary central nervous system involvement (PCNSL) and primary central nervous system with ocular involvement (PCNSLO). The difference between PCNSL and PCNSLO is that PNSCL involves the central nervous system, while PCNSLO does not. 56-86% of orbital lymphomas are classified PCNSL and 15-25% are classified PCNSLO.PCNSLO is common in people who are severely immunosuppressed. Symptoms of this form of ocular lymphoma include painless decreased vision, sensitivity to light, a red eye, and floaters. Diagnosis is difficult due to its gradual onset and the fact that the symptoms are the same as other diseases. PCNSLO is usually bilateral, but sometimes grows unevenly. Like other metastatic tumors of the eye, it is usually confined to the choroid. Signs and symptoms
Primary visible signs of ocular lymphoma include proptosis and a visible mass in the eye. Symptoms are due to mass effect. Pathophysiology
Recent studies have detected the presence of viral DNA in ocular lymphoma cells. This implies that pathogens play a role in ocular lymphoma. Other studies have found that the aging population, the increasing number of immunosuppressive drugs, and the AIDS epidemic have also contributed to the increased incidence of Non-Hodgkin lymphomas.
Complement deficiency is an immunodeficiency of absent or suboptimal functioning of one of the complement system proteins. Because of redundancies in the immune system, many complement disorders are never diagnosed. Some studies estimate that less than 10% are identified. Hypocomplementemia may be used more generally to refer to decreased complement levels, while secondary complement disorder means decreased complement levels that are not directly due to a genetic cause but secondary to another medical condition. Signs and symptoms
The following symptoms (signs) are consistent with complement deficiency in general:

Complications
Vaccinations for encapsulated organisms (e.g., Neisseria meningitidis and Streptococcus pneumoniae)  is crucial for preventing infections in complement deficiencies. Among the possible complications are the following:

Deficiencies of the terminal complement components increases susceptibility to infections by Neisseria. Causes
The cause of complement deficiency is genetics (though cases of an acquired nature do exist post infection). The majority of complement deficiencies are inherited as autosomal recessive conditions, while properdin deficiency occurs through X-linked inheritance. MBL deficiency can be inherited by either manner. Inherited
Properdin deficiency is an X-linked disorder that also causes susceptibility to Neisseria infections. C1-inhibitor deficiency or hereditary angioedema will have low C4 with normal C1 levels. Acquired
Acquired hypocomplementemia may occur in the setting of bone infections (osteomyelitis), infection of the lining of the heart (endocarditis), and cryoglobulinemia. Systemic lupus erythematosus is associated with low C3 and C4. Membranoproliferative glomerulonephritis usually has low C3. Mechanism
The mechanism of complement deficiency consists of:

C2: In regard to C2 deficiency, about 5 different mutations in the C2 gene are responsible.