The most common organism causing chorioretinitis in HIV is
(Refer: AK Khurana Comprehensive Ophthalmology, 6th edition, pg no. 470 - 472)Cytomegalovirus (CMV) is the most common cause of chorioretinitis in patients who are HIV positive
CMV retinitis
Toxoplasma chorioretinitis
Syphilitic retinitis
Pneumocystis carini
Vitreous and retina