53.1 Features
Ocular toxocariasis (OT) is a helminthic disease that may cause a large spectrum of ocular complications. It is one of the most common parasitic causes of visual loss in the world, particularly in children. Infection usually results from accidental ingestion of dirt that has been contaminated with dog or cat feces that contain infectious Toxocara eggs. Rarely, people can also become infected from eating undercooked meat containing Toxocara larvae. OT occurs when the Toxocara larvae migrate to the eye with symptoms, including vision loss, eye inflammation, and damage to the retina. Serum and vitreous testing for specific Toxocara immunoglobulin G aids in diagnosis and ultrasonography is vital for evaluating leukocoria to help distinguish between other possible diagnoses.
53.1.1 Common Symptoms
Often asymptomatic. Ocular symptoms are usually unilateral and include blurry vision, floaters, and other potential signs of inflammation.
53.1.2 Exam Findings
In its most common form of endophthalmitis, it presents in the retina and vitreous, possibly as a yellow-white lesion and often with vitritis. Retinal detachment and leukocoria may be present, and hypopyon may develop in severe cases. A peripheral granuloma, noted as a white elevated mass, may be present in the peripheral retina and/or ciliary body region with possible falciform folds with associated retinal dragging in late stages. Alternatively, it may present as a posterior granuloma that may have indistinct borders with overlying vitritis in the acute stage (▶ Fig. 53.1). As the acute inflammation subsides, the granuloma typically becomes more defined and consolidated. In optic papillitis, the optic disc will be elevated with telangiectatic vessels and possible subretinal exudate. Other ophthalmic findings include amblyopia and strabismus.
Fig. 53.1 Fundus photograph of a posterior granuloma with whitish subretinal lesion in the macula.
53.2 Key Diagnostic Tests and Findings
53.2.1 Optical Coherence Tomography
Optical coherence tomography may demonstrate the localization of the granuloma with choroidal involvement and rupture through Bruch’s membrane and the retinal pigment epithelium. Outer retinal involvement with possible associated subretinal and intraretinal fluid is seen during the acute inflammatory phase (▶ Fig. 53.2).
Fig. 53.2 (a,b) Optical coherence tomography over granuloma demonstrating outer retinal involvement from the lesion emerging from the choroid. Associated subretinal fluid is present.
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