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ocular_toxoplasmosis [2025/01/27 22:41] Scott Larsonocular_toxoplasmosis [2025/04/18 20:40] (current) – external edit 127.0.0.1
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 ====== Ocular Toxoplasmosis ====== ====== Ocular Toxoplasmosis ======
- +  * Caused by Toxoplasma gondii
-===== Toxoplasma gondii =====+
   * Obligate intracellular protozoan   * Obligate intracellular protozoan
   * 500 million have antibodies worldwide   * 500 million have antibodies worldwide
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   * Propensity for cardiac and skeletal muscle and neural tissue (brain & eye)   * Propensity for cardiac and skeletal muscle and neural tissue (brain & eye)
  
-===== Clinical Manifestations ===== +==== Clinical Manifestations ==== 
-==== Acquired vs. Congenital ====+=== Acquired vs. Congenital ===
   * Most cases are presumed reactivation of congenital infection   * Most cases are presumed reactivation of congenital infection
   * 2 to 6/1000 women acquire infection while pregnant, 40% risk of transmission to fetus.   * 2 to 6/1000 women acquire infection while pregnant, 40% risk of transmission to fetus.
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   * Northern Brazil has high rate of acquired disease   * Northern Brazil has high rate of acquired disease
  
-==== Systemic ====+=== Systemic ===
   * 90% lympadenopathy   * 90% lympadenopathy
   * fever, malaise, occasional sore throat   * fever, malaise, occasional sore throat
   * immunocompromised- fulminant CNS disease   * immunocompromised- fulminant CNS disease
  
-==== Ocular ====+=== Ocular ===
   * Keratic Precipitates, anterior chamber cell and flare, posterior synechia, cataract   * Keratic Precipitates, anterior chamber cell and flare, posterior synechia, cataract
   * Retinochoroiditis   * Retinochoroiditis
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   * FFA of active lesion- early blockage and subsequent leakage   * FFA of active lesion- early blockage and subsequent leakage
  
-==== Atypical Presentations ====+=== Atypical Presentations ===
   * In early infection: gray-white fine punctate lesions in deep retina and RPE, progress to more classic lesions   * In early infection: gray-white fine punctate lesions in deep retina and RPE, progress to more classic lesions
   * Papillitis, vitreal inflammation, nerve fiber bundle defects   * Papillitis, vitreal inflammation, nerve fiber bundle defects
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   * Wide ring-like lesion near extreme periphery resembling pars planitis   * Wide ring-like lesion near extreme periphery resembling pars planitis
   * Scleritis   * Scleritis
-==== Reasons for Vision Loss ====+=== Reasons for Vision Loss ===
   * Vitreal inflammation causing clouding   * Vitreal inflammation causing clouding
   * Lesion in posterior pole with edema affecting fovea   * Lesion in posterior pole with edema affecting fovea
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   * Subsequent CNVM   * Subsequent CNVM
  
-===== Diagnosis =====+==== Diagnosis ====
   * Typical lesions   * Typical lesions
   * Toxoplasmosis titers are supportive   * Toxoplasmosis titers are supportive
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   * Angiography: flourescein tagged Ab (successful in rabbit studies)   * Angiography: flourescein tagged Ab (successful in rabbit studies)
  
-===== Therapy =====+==== Therapy ====
   * Should you treat it at all?   * Should you treat it at all?
     * Lesion within temporal arcade     * Lesion within temporal arcade
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   * Generally 4-6 weeks, multi-drug regimens   * Generally 4-6 weeks, multi-drug regimens
  
-===== Medications =====+==== Medications ====
   * Sulfadiazine 1g PO QID   * Sulfadiazine 1g PO QID
   * Pyrimethamine 75-100mg load and 25-50mg PO BID (bone marrow suppression, nausea)   * Pyrimethamine 75-100mg load and 25-50mg PO BID (bone marrow suppression, nausea)
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   * recurrence rate at 3 years (42%)   * recurrence rate at 3 years (42%)
  
-==== Treatment Regimen #2 ====+== Treatment Regimen #2 ==
   * Clindamycin, Sulfadiazine, Prednisone   * Clindamycin, Sulfadiazine, Prednisone
   * Reducing size of lesions >1/2 DD (28%)    * Reducing size of lesions >1/2 DD (28%) 
   * med side effects (17%)   * med side effects (17%)
   * recurrence rate at 3 years (67%)   * recurrence rate at 3 years (67%)
-==== Treatment Regimen #3 ====+== Treatment Regimen #3 ==
   * Co-trimoxazole, Prednisone   * Co-trimoxazole, Prednisone
   * Reducing size of lesions >1/2 DD (11%)   * Reducing size of lesions >1/2 DD (11%)
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   * recurrence rate at 3 years (40%)   * recurrence rate at 3 years (40%)
  
-==== Treatment Regimen #4 ====+== Treatment Regimen #4 ==
   * No treatment (peripheral lesions)   * No treatment (peripheral lesions)
   * Reducing size of lesions >1/2 DD (20%)   * Reducing size of lesions >1/2 DD (20%)
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   * recurrence rate at 3 years (53%)   * recurrence rate at 3 years (53%)
  
-==== Comments ====+== Comments ==
   * Recurrence rates not statistically significant   * Recurrence rates not statistically significant
   * Size of retinal lesion correlated with duration of inflammation   * Size of retinal lesion correlated with duration of inflammation