Atypical Presentation of Ocular Toxoplasmosis: A Case Report of Exudative Retinal Detachment and Choroidal Ischemia.

A 24-year-old healthy male presented with a chief complaint of blurred vision in the right eye for 1-week. Fundus examination indicated right exudative retinal detachment and choroidal ischemia. The patient responded well to anti-toxoplasmosis medications and steroids. Exudative retinal detachment and choroidal ischemia are atypical presentations of ocular toxoplasmosis. However, both conditions responded well to anti.parasitic therapy with steroid.

INTRODUCTION

Ocular toxoplasmosis represents the most common cause of infectious retinochoroiditis in adults and children. It is caused by the obligate intracellular parasite Toxoplasma gondii.1 The typical presentation of ocular toxoplasmosis is characterized by focal retinochoroiditis adjacent to pigmented chorioretinal scar and vitreous inflammation.2 In addition to the typical presentation of this disease, atypical forms of ocular toxoplasmosis have been observed.3456 These include punctuate outer retinal toxoplasmosis,3 retinal vasculitis, retinal vascular occlusion, rhegmatogenous and serous retinal detachment,45 optic neuropathy, and scleritis.6 In this case report, we highlight an atypical presentation of ocular toxoplasmosis in a young male.

CASE REPORT

A 24-year-old healthy male presented to King Khalid Eye Specialist Hospital, Riyadh, Saudi Arabia, complaining of blurred vision in his right eye for 1-week. Best corrected visual acuity was 20/70 in the right eye and 20/20 in the left eye. Intraocular pressures were normal bilaterally. In the right eye, there were no keratic precipitates and the anterior chamber was quiet with no cells or flare. Vitreous cavity was quiet and clear. Clinically, evident exudative retinal detachment was visible on dilated fundus exam and documented with optical coherence tomography (OCT). The exudative retinal detachment included the macula with deep creamy yellow choroidal infiltrates adjacent to an old chorioretinal scar along the superior temporal arches. The left eye was unremarkable. Fluorescein and indocyanine green angiography revealed two areas of early hypofluorescence at the choroidal level, which persisted to the final phase with surrounding hyperfluorescence on fluorescein angiography. Late indocyanine green showed defined areas of hypofluorescence corresponding to a scar and recent choroidal ischemia [Figure 1]. IgG and IgM were positive for toxoplasmosis.

Figure 1

At presentation (a) Color fundus photograph of the right eye showed chorioretinal scar along the superotemporal arcade, deep creamy lesion inferior to the scar with bleb like subretinal fluid with macular involvement as demonstrated in the optical coherence tomography (b); (c and d) two areas of early hypofluorescence at the choroidal level which persist in the end phase with surrounding hyperfluorescence on fundus fluorescein angiography more intense inferior to the superotemporal arcade which represent the choroidal ischemia, late indocyanine green angiography showed defined areas of hypofluorescence corresponding to a scar and recent choroidal ischemia (e and f)

Based on the clinical presentation, fluorescein angiography, OCT, and serology, the patient was diagnosed with atypical ocular toxoplasmosis with exudative retinal detachment and choroidal ischemia. The patient was managed with Bactrim and clindamycin for 6 weeks. Oral prednisolone 1 mg/kg was initiated after 48 h of antiparasitic therapy.

Three months after initiating treatment, the clinical presentation improved with complete resolution of subretinal fluid and restoration for vision to 20/20. 6 months from initial therapy, vision remained 20/20 with complete remission of signs and symptoms [Figure 2].

Figure 2

Three months later, complete resolution of the subretinal fluid is seen in (a-c); area of hyperfluorescence corresponding to a window defect inferior to the superotemporal arcade secondary to the choroidal ischemia

DISCUSSION

This case is an atypical presentation of ocular toxoplasmosis based on the presentation of exudative retinal detachment, choroidal ischemia, and the absence of vitritis. However, the presence of a previous chorioretinal scar aided the diagnosis, and the positive serology confirmed the diagnosis.

Vitreous inflammation (vitritis) is usually more intense near the active retinochoroiditis. However, minimal or no vitritis can be observed when the inflammation is distant from the inner retina specially if it does not exceed the inner limiting membrane toward the vitreous.7 In our case, there was no vitritis since the active inflammation was deep in the choroid sparing the inner retina [Figure 1a].

In this case, the exudative retinal detachment was likely due a temporary dysfunction in retinal pigment epithelial (RPE). Inflammatory processes or choroidal ischemia may contribute to RPE decompensation causing accumulation of subretinal fluid.

Choroidal ischemia is a rare phenomenon in ocular toxoplasmosis. Khairallah et al.8 evaluated 60 eyes and reported choroidal ischemia in only 5 eyes. Choroidal ischemia can be detected with fluorescein and indocyanine green angiography, which image areas of choroidal hypoperfusion.

Alternately, exudative retinal detachment is often under-diagnosed in ocular toxoplasmosis. Hence, OCT imaging can be beneficial for discovering subclinical subretinal fluid. Subclinical cases represented more than 50% (8 eyes out of 14) Khairallah et al.8 study. Hence, poor visual acuity can be explained in a subset of patients with chorioretinal involvement distant from the macula.

A careful history, thorough examination, and a tailored work up cannot be over emphasized in suspect cases as treating inflammatory exudative retinal detachment with steroid alone can lead to devastating outcomes. We elected coverage with antiparasitic agents before initiating steroid therapy.

In summary, this case was an atypical manifestation of ocular toxoplasmosis presenting as choroidal ischemia and exudative retinal detachment which resolved in response to appropriate therapy.