History of Presenting Illness: 14 year-old White male presents with blurry vision in both eyes.
Ocular History: Visual problems noticed few weeks prior to presentation. He gives a history of having a bet with his friends on who can stare at the sun the longest! He was so proud to have won that bet by staring at the sun for five minutes with his right eye only.
Medical History: Otherwise healthy young man
Social History: Lives with his parents on a farm.
Family History: Noncontributory
Allergies: None
Review of Systems: Noncontributory
Current meds: None
Ocular Exam:
-No external/periorbital lesions
-EOM full
-Orthophoric at distance/near
-No field defects by confrontation
-No APD
-Vision with correction : OD 20/400 OS 20/60
-IOP OD 14 mmHg OS 17mmHg
SLE
L/L: clean without crusting or lesions OU
C/S: white and quiet OU
K: Clear with no KP’s OU
A/C: Deep and Quiet OU
I: round and reactive. No lesions, OU
Lens: Clear OU
Anterior vitreous: OD quiet, OS few cells
Dilated Fundus Exam:
Vitreous was clear OD and 1+ vitritis was present OS
- Fundus Pictures
Fluorescein Angiogram
Differential Diagnosis:
Toxoplasmosis
Toxocariasis
Fungal Chorioretinitis
CMV Retinitis
Tuberculosis
Diagnosis:
The fundus findings are most consistent with active Toxoplasmosis OS with an old Toxo scar in the macula OD
Discussion:
Infection with Toxoplasma gondii is usually congenital but can also be acquired. Ocular toxoplasmosis is typically a recurrent manifestation of congenital disease. It is the most common protozoal eye infection and the most frequent cause of focal retinitis in healthy adults.
Symptoms
Floaters and blurry vision are the most common
Symptoms are present in over 90% of active disease.
Signs
Unilateral, white yellow focal retinal lesion (retinitis)
Overlying vitritis. Vitritis could be dense giving the classic “headlight in the fog” appearance
Chorioretinal scar adjacent to the active lesion or in the fellow eye.
Occasionally, associated hemorrhage, vasculitis can be seen
Papillitis, mild iritis, scleritis can also be present
Diagnosis
Typically made clinically without the need for serology
FA findings: late staining of the area of retinitis with hyperfluorescence of the optic disc.
Pathophysiology
Infection occurs through ingestion of T. gondii oocysts from cats (acquired) or by maternal transplacental spread (congenital)
Mother usually is infected while pregnant
If parasite reaches the eye, a retinitis takes place with secondary choroiditis.
The immune system controls the infection and the organism encysts and remain dormant for years.
The cysts eventually rupture releasing organisms into surrounding retina.
Treatment
Self-limited disease in immunocompetent patients
Treatment indicated if:
Retinitis lesion is 2-3mm from fovea or the optic disc
Extrmacular lesions with severe retinitis
Therapy consists of pyrimethamine, sulfadiazine, folinic acid and steroid
Bactrim and Clindamycin have been used
Oral steroid should never be given without concurrent antibiotics.
Prognosis is usually good unless retinitis involes the fovea or optic nerve.
