This document presents a case study of ocular toxoplasmosis in a 42-year-old female. It describes the typical clinical presentation including blurred vision, vitritis, chorioretinal scarring and an adjacent active white lesion. It discusses the pathogenesis of acquired versus congenital toxoplasmosis and treatment with antibiotics and steroids. Key findings are the classic "headlight in the fog" appearance and that acquired toxoplasmosis is more common than previously believed, often occurring without symptoms on initial infection.

1. Facts about ocular
toxoplasmosis through a case
Samhaa Mohammed Abd Elmoneim
FRCS Glasgow, Egyptian Fellowship, MSc.
Zagazig Ophthalmic Hospital
(2022)
Samhaa Mohammed

2. Samhaa Mohammed
42 years-old female
complains of gradual
blurring of vision (OD)
over the last 2 weeks.
She is medically free
BCVA 6/60, 6/6?
Cause of blurred
vision in
toxoplasmosis is most
probably due to
macular/ ON
involvement, severe
vitritis, vasculitis, CNV
on top of old scar
https://webeye.ophth.uiowa.edu/eyeforum/cases
/74-Acquired-Toxoplasmosis-Retina.htm

3. Samhaa Mohammed
Milder than posterior involvement
(fine kps, cells +1)
Anterior
segment
https://webeye.ophth.uiowa.edu/eyeforum/cases
/74-Acquired-Toxoplasmosis-Retina.htm

4. Samhaa Mohammed
https://webeye.ophth.uiowa.edu/eyeforum/cases
/74-Acquired-Toxoplasmosis-Retina.htm
Posterior segment
Vitreous opacitis (obscuring
retina), vasculitis
Active inflammation
Chorio-retinal pigmented scar
(old)
Adjacent fluffy white lesion
(reactivation)
Classic presentation

5. Samhaa Mohammed
https://webeye.ophth.uiowa.edu/eyeforum/cases
/74-Acquired-Toxoplasmosis-Retina.htm
Posterior segment
Chorio-retinal pigmented scar
(old)
Adjacent fluffy white lesion
(reactivation)
Classic presentation
Headlight in fog
White fluffy lesion in vitritis

6. Samhaa Mohammed
https://webeye.ophth.uiowa.edu/eyeforum/cases
/74-Acquired-Toxoplasmosis-Retina.htm
Posterior segment
Peri arterial (Kyrieleis)
plaques near the
active lesion
Retinal tissue, vessels,
choroid, vitreous

7. Samhaa Mohammed
Why posterior
involvement?
Dormant bradyzoites in
retinal tissues
Tachyzoite erupt in activity
Water
Food

8. Samhaa Mohammed
Is it congenital
or acquired?
Acquired is more common
and usually passed
unnoticed in the first
attack of activity (flue like
illness)

9. Samhaa Mohammed
When trans-
placental
transmission is
occurred from
infected mother
to fetus?
If mother is infected
during 1st 6 months of
conception, fetus can be
infected in 30%
Cranial and systemic
involvement
Ocular (retinochoroiditis,
microphthalmos, cataract,
optic n atrophy,
strabismus)

10. Samhaa Mohammed
Is it the first
attack of
infection in this
case?
(TYPICAL
toxoplasmosis)
No
1st activity is usually
insidious and
asymptomatic (flu like
symptoms). We cannot
determine when the 1st
infection had occurred.
Chorioretinal Scar is the
classic clue for a previous
attack.

11. Samhaa Mohammed
What is different
clinically for
immunesuppress
ed patient?
In immunosuppressed
individuals, lesions tend to
be multiple, bigger, and
bilateral.
CNS involvement!

12. Samhaa Mohammed
Despite these
classical clinical
finding, what are
other helpful
investigations?
Ig M titre (recent infetion)
Ig G titre (old infection)
-ve in immunesuppressive
despite infection → PCR
(aqueous or vitreous) to
exclude other serious DD

13. Samhaa Mohammed
What are DD?
TB
Behcet
Sarcoid
Syphilis
CMV
HIV
Herpetic ARN
Masquerade (lymphoma)
CBC
CT chest, QGT,
ACE
CMV Ab titer
FTAb, RPR..

14. Samhaa Mohammed
When Tx is indicated?
Macular
area/ON
involvement
Severe vitritis
Immunesupp
red patients
(bilateral,
multifocal,
CNS)
Observe in immunecompetent with
unilateral, minimal uveitis, peripheral and
unifocal lesion

15. Samhaa Mohammed
How to treat?
Oral AB
Oral steroid
40mg/d after
2 d from AB
start then
tapering
intravitreal
clindamycin
(1 mg in 0.1
ml)
(hypersensiti
vity!)
Topical steroid
Cycloplegic for anterior uveitis +/- IOP↓

16. Samhaa Mohammed
Which AB?
Trimethoprim
e-
sulfamethoxaz
ole, double-
strength
(1 tab bid)
Clindamycin
300 mg qid
Pyrimethamin
e 50mg bid 1st
d, then 25mg
bid,
sulfadiazine2g
qid 1st d, then
1g qid,
Azithromycin
500mg 1st day
then 250 mg
qd for 5 wk
Folinic acid 3-5 mg biw

17. Samhaa Mohammed
Posterioer segment
after 6wks of Tx
https://webeye.ophth.uiowa.edu/eyeforum/cases
/74-Acquired-Toxoplasmosis-Retina.htm

18. To conclude what we learn today
• Toxoplasmosis is the most common cause of
infectious posterior uveitis
• Acquired is more common than congenital (against
what was believed). Infection not necessitate
systemic or ocular C/P/ presence of lesions.
• Acute 1st attack is usually asymptomatic and
unnoticed in immunecommpotent patients
• Congenital transplacental transmittion is occurred
in a newly infected mother during the 1st 6 months
of conception (only in 30% of those cases).
• Congenital ocular toxoplasmosis involves macula and
is associated with microphthalmia, nystagmus,
strabismus, and intracranial/ systemic CP
• Activity on top of old infection pathogenesis due to
release of tachyzoites from dormant bradyzoites
Samhaa Mohammed

19. To conclude what we learn today
• Classic infection in immune-competent is unilateral
with white lesion with indistinct margins and
overlying focal vitreous infiltrate in a unifocal area
adjacent to an old chorioretinal scar
• Older pigmented lesions in clusters are due to
several attacks of activity
• Chorio-retinal lesions with severe vitritis is typical
and is called "headlight in the fog" appearance
• Vascular involvement can be detected near the
lesions
• In immuno-compromised, severe infection is
detected and lesions are bilateral and multifocal.
• Tx is indicated in immune-suppressed, bilateral,
vitritis, macula or optic nerve involvement
Samhaa Mohammed

20. Samhaa Mohammed
Thank
you