Sitting at the window to the world--ocular parasites

Longitudinal Optical Coherence Tomographic follow-up of a 10-year-old girl with unilateral retinal parasitism

Objective

Retinal parasitism by worms is a rare clinical occurrence and may cause diagnostic and therapeutic challenges. We present a girl with unilateral involvement who was first diagnosed at the age of 10. Change in parasite appearance inside the lesion was recorded by optical coherence tomography (OCT) 14 years apart.

Methods

Case report.

Results

A 10-year-old girl was referred to our clinic with a presumptive diagnosis of a unilateral posterior pole mass. She had been examined at another institution for the left exotropia and decreased vision, without any accompanying systemic symptoms. Upon our examination, a subretinal lesion, of two disc diameters in size, was detected two disc diameters above the left optic disc, and a spiral-shaped, non-motile roundworm could be spotted inside the lesion. Adjacent chorioretinal atrophy and marked fibrosis surrounded the lesion, without any active inflammation. OCT sections through the lesion delineated the hyperreflective appearance of the spiraling roundworm. Fourteen years later, the worm inside the lesion had lost its spiraling form, and the remnants appeared as a coalesced whitish material inside the lesion on the OCT.

Discussion

Although rare, retinal parasitism by worms presents significant diagnostic challenges due to its atypical presentation and the potential for misdiagnosis. In this case, the initial presentation of a subretinal lesion containing a spiral-shaped roundworm was notable for its lack of associated systemic symptoms and the absence of active inflammation, often seen in more common ocular infections. The long-term follow-up, using OCT, provided valuable insights into the infection's natural course, showing the gradual degeneration and transformation of the parasite into a coalesced whitish material, over 14 years. This case underlines the importance of longitudinal imaging in understanding the progression of such unusual retinal conditions and the need for awareness of parasitic infections as a differential diagnosis in similar clinical scenarios.

Conclusions

The present case demonstrates the natural evolution of the inactive subretinal worm by OCT and color fundus images.

Parasitic keratitis - An under-reported entity

Parasitic keratitis (PK) is unique entity among parasitic infections where corneal involvement could result from direct inoculation of the parasite via exogenous environment or spread via endogenous neighboring organs or as a result of immune-mediated damage secondary to a systemic parasitic infection. Most cases of PK are caused by Acanthamoeba spp. and Microsporidia spp. though few other parasitic agents can also lead to corneal involvement. Mimicking as other infectious and non-infectious causes of keratitis, PK often escapes detection. This review summarizes the predominant causes of PK along with the epidemiological, clinical and microbiological details of each. Though several gaps exist in our understanding of the prevalence of PK, the one thing for sure is that PK is on the rise. With advanced diagnostic modalities and enough literature on optimal management of cases of PK, it is now imperative that a strong clinical suspicion of PK is kept when examining a case of corneal pathology and adequate investigations are ordered.

Coinfections and differential diagnosis in immunocompetent patients with uveitis of infectious origin

BACKGROUND

Making a definite diagnosis of infectious uveitis is a challenging task because many other infectious, and non-infectious uveitis, may have similar non-specific symptoms and overlapping clinical appearances. Co-infections in immunocompetent patients are not frequently proved with traditional serologic-diagnostic tools.

METHODS

Descriptive transversal study, in a Uveitis Service of an Ophthalmology Reference Center, in Bogotá, Colombia, from July 2014 to February 2016. Aqueous humor (AH) and/or vitreous fluid, blood and serum samples were collected from consecutive patients suspected of having infectious uveitis. The diagnosis of ocular toxoplasmosis (OT) was confirmed by the Goldmann-Witmer coefficient (GWC) and by polymerase chain reaction (PCR). Differential diagnosis by PCR in AH was done for viral origin such as Cytomegalovirus (CMV), Herpes simplex virus type 1 (HSV1), Herpes simplex virus type 2 (HSV2), Varicella zoster virus (VZV), Epstein-Barr virus (EBV) and Mycobacterium tuberculosis.

RESULTS

In 66 Colombian patients with uveitis of presumed infectious origin: 22 (33.3%) were confirmed as OT, 16 (24.2%) as undetermined OT, five (7.5%) as co-infections and 23 (34.8%) as other uveitis. Toxoplasma coinfection with M. tuberculosis was identified in one case by PCR and in four cases with HSV by GWC. The initial clinical diagnosis changed, after laboratory examination, in 21 cases (31.8%).

CONCLUSIONS

Clinical diagnosis can be changed by laboratory examination in a significant proportion of cases of uveitis. Diagnosis of OT should combine the use of PCR and GWC to reach the maximum of confirmation of cases. The use of multiple laboratory methods is necessary to identify co-infections and viral infections that can mimic OT in immunocompetent patients.