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| Ocular
toxoplasmosis occurs secondary to an infection by the protozoa, Toxoplasma
gondii. Although acquired
toxoplasmosis may be seen, the majority of cases are felt to be a
reactivation of a congenital toxoplasmosis infection.
Clinically, an active infection is characterized by an acute
retino-choroiditis with a marded vitreous reaction overlying the active
infection, leading to the characteristic fundus picture of the optic nerve
appearing as a "headlight in the fog."(#22226)
The healed lesion leads to a large scar, often with the white
appearance of sclear near the center of the scar with heavy pigmentation
seen peripherally (#22228, #22229). Histopathologically, the active infection is characterized by
a protozoal infection of the retinal and the choroid(#9853) leading to
coagulative necrosis of the retina with a diffuse granulomatous
inflammation of the underlying choroid.
The toxoplasma scar shows an abrupt transition of normal retina to
the area of scar with extensive destruction of retina, RPE, and choroid
with marked disruption of pigment(#22231).
See also
(#22959, #22962).
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| Fundus
Photo #22226 |
Fundus
Photo #22228 |
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| Gross
Photo #22229 |
Low
Power #9853 |
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| Medium
Power #22231 |
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