Toxoplasma Retinochoroiditis

Toxoplasma Retinochoroiditis

- Most common cause for infectious posterior uveitis.

- Mainly caused by 3 strains of toxoplasma gondi. In which type II is severe and high chances of recurrences

- can be congenital or acquired.

- Clinical features:

       1. Congenital- well defined punched out  hyperpigmented chorioretinal atrophy most commonly involving the macula and posterior pole. There can be underlying scleral show

 Why macula is most commonly involved?

 As in early deveopment of eye posterior pole is first developed
Toxoplasma cysts gets encystedin smaller arterioles which are present near the macula.
While resolution there can be associated vitreous adhesion and later ERM can develop.

        2. Acquired - 

Typical:
Yellowish white necrotizing retinitis adjacent to the old scar with associated vitritis. If vitritis is more then retinitis lesion appears as headlight in fog appearence which is chracteristic but not so commonly seen in India.
If lesion very close to fovea can be associated with neurosensory detachment
Vasculitis which can be skip, confluent or kaeyeralis can be present adjacent or far away from the lesion

Atypical:
Most commonly in the immunocompromised patients
Characteritised by new retinitis lesion which has vertical spread and can involve the optic disc.
Can also cause Acute Retinal Necrosis
Can have multiple retinitis lesions


- Investigations: 

FFA: early hypofluorescence with then perilesional hyperfluorescence lesion

OCT: full thickness necrotizing retinitis with adjacent vitreous cells. 


- Treatment: 

Not all lesions need to be treated especially when the scarred one and the active lesion smaller in the periphery.
If the patient has significant visual loss, involving posterior pole , recurrent toxoplamosis needs treatment.

Most common regime being double strength of sulphamethaxozole and trimethoprim given for 6 weeks.
Other agents like azithromycin, pyrimethamine ,clindamycin can be used.
If the patient is not compliant with oral medications or the lesion is very close to fovea and optic disc we can inject intravitreal clindamycin or cotrimoxazole.

Role of oral steroids; oral steroids can be started along with antitoxoplasma agents as it helps to decrease the inflammation and also hyperpigmentation of the lesion.