الفهرس 
Pathophysiology of Antiphospholipid SyndromeOnly 14 pages are availabe for public view
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Abstract
Antiphospholipid syndrome is defined as the presence of aPLs, arterial or venous thrombosis, recurrent spontaneous abortions, and thrombocytopenia. However, not all patients develop such complications. The risk of thrombotic event in patients with APS is 0.5 to 30%. The syndrome can occur within the context of several diseases, mainly autoimmune, or it may be present without any recognizable disease, the so-called primary APS.
The mechanism of action of aPLs is not known. It has been shown, that the antibodies bind to the anionic PL of platelet membranes, endothelial cells, and clotting components such as prothrombin, protein C and protein S. The simplest theory is that there is an antibody directed against the patient’s own platelet and endothelial cell PL that cause platelet aggregation and subsequent vascular occlusion. This also accounts for thrombocytopenia seen in these patients. However, the mechanism of action seems to be more complex and probably not all participating components are known yet.
Familial occurrence of elevated levels of aPLs as well as an association with certain HLA DR4, DR7, DQw7, and DQw53 types were reported. Approximately 4 % of normal population has elevated levels ACL.
Ocular manifestations can also be multi-symptomatic, Patients can complains of blurred vision, transient diplopia, transient field loss, amaurosis fugax and photopsia. Almost 90% of patients with primary APS have ocular involvement. However, 30% of them can be asymptomatic. Visual acuity is markedly decreased in about 15% of the eyes. The most serious changes might be seen in the retina and optic nerve.
Pathological manefistation in the eye lids were erythema, purpura and telangiectasia, in the cornea and conjunctiva, keratoconjunctivitis sicca (KCS) (2ry Sjogren’s syndrome), punctuate epithelial keratitis, peripheral ulcerative keratitis, in the sclera scleritis and episcleritis in the iris and ciliary body anterior uveitis, seldom occurs in isolation.
APS chorioretinopathy consists of the chorio-retinal and optic nerve vaso-occlusive lesions found in APS cases, The APS chorioretinopathy could be classified into two main types:
Type I (mild or microangiopathic APS chorioretinopathy):
Type II (severe or vaso-occlusive APS chorioretinopathy), that has also two clinical variants:
• Type II-A (focal vaso-occlusive APS chorioretinopathy).
• Type II-B (diffuse vaso-occlusive APS chorioretinopathy).
Neuroophthalmic changes
- Anterior non-arterial ischemic optic neuropathy (NAION).
- Retrobulbar neuritis.
- Progressive optic atrophy.
Systemic manifestations of APS are multi-symptomatic and can affect most of the systems. The symptoms are secondary to the thrombosis that can be located in the vessels of each caliber. Most commonly APS is associated with SLE.
Neurology: cerebral ischemia, stroke, migraine, epilepsy, chorea, myelopathy, multiple sclerosis.
Cardiology: myocardial infarction, pulmonary hypertension, valvular disease.
Dermatology: livedo reticularis, Sneddon’s syndrome, skin ulcers, skin nodules.
Hematology: thrombocytopenia, idiopathic thrombocytopenic purpura, autoimmune hemolytic anemia.
Nephrology: renal vein thrombosis, glomerular thrombosis, thrombotic microangiopathy, vasculitis, malignant hypertension.
Obstetrics: recurrent spontaneous abortion.
The diagnosis of APS is based on the presence of aPLs (ACL and LAC). A potential presence of systemic disease must be excluded. Detailed examination of the conjunctival and retinal vessels including FA is helpful not only for the eye evaluation, but also for the evaluation of the systemic microcirculation, the picture of which is mirrored in the eye. Vitreous opacity, pigment epithelial window defects, early hyper fluorescence of atrophic areas, occlusive retinopathy with fluorescein leakage, areas of retinal hypoperfusion, neovascularization, and unsuspected occlusion can be presented on fluorescein angiography.
Anticoagulation and immunosuppression seem to be the most effective treatment. Long-term therapy with aspirin, warfarin or heparin was suggested, but duration of the treatment and the point at which it should be discontinued are not clear. The level of INR is recommended to be more than 3. Life-long anticoagulation is necessary in some patients. Laser photocoagulation is an additional treatment of non-perfused retinal areas.
Treatment can be modulated based on the levels of INR and aPLs. Patients with IgG-ACL are at higher risk than those with IgM or IgA antibodies. The probability of thrombosis is higher if both ACL and LAC are present simultaneously. Significantly higher incidence of thrombosis was also described in patients who had elevated levels of IgG anti beta-2-GP I antibodies