Role of ultrasound biomicroscopy in diagnosis of ocular toxocariasis

Pediatric Posterior Infectious Uveitis

PURPOSE

To describe the most important cause of infectious posterior uveitis in pediatric patients.

METHODS

Review of the literature.

RESULTS

The most important causes of infectious uveitis in pediatric patients are: cat-scratch disease, toxocariasis, tuberculosis, viral diseases and toxoplasmosis. Ocular manifestations include retinitis, neuroretinitis, choroidal granulomas, peripheral granulomas and posterior pole granulomas.

CONCLUSION

Infectious posterior uveitis is a challenging subject and should be considered in the differential diagnosis of any posterior uveitis in children. Infectious uveitis must be excluded before initiating immunosuppressive therapy.

Management of presumed trematode-induced granulomatous intermediate uveitis

PURPOSE

To describe the surgical management of presumed trematode-induced granulomatous intermediate uveitis (PTIGIU) not responding to medical treatment in controlling the inflammation.

METHODS

A prospective, interventional, single-center study in which patients with a history of fresh canal water contact and PTIGIU were enrolled. All patients underwent lensectomy-pars plana vitrectomy (PPV) and post-operative control of inflammation, functional and anatomical outcomes were assessed.

RESULTS

Fifteen eyes of 12 patients were included in the study with median age of 11.6 ± 4 yrs. Six months following lensectomy-PPV, inflammation was well controlled in all patients. The eyes were divided into two groups: Group A: 10 patients with an attached retina while Group B: 5 patients who were in the cicatricial stage with tractional retinal detachment. All patients in group A had CDVA of 20/40 or better, unlike patients in group B who failed to achieve a CDVA better than 20/70 throughout their follow-up. In group B, final anatomical success was achieved in only 40% with hypotony occurring in 20%.

CONCLUSION

PTIGIU is associated with the presence of ciliary body granuloma which, if left untreated, can lead to drastic outcomes. Early lensectomy-PPV represents a viable management option in cases resistant to medical treatment, with a favorable outcome.

Case report: Ultrasound biomicroscopy as a guide for the selection of injection sites for dexamethasone intravitreal implant (Ozurdex) for peripheral granulomatous ocular toxocariasis in children

Purpose

This article aims to report a case of successful treatment of peripheral granulomatous ocular toxocariasis (OT) in an 8-year-old patient using intravitreal injection of dexamethasone (DEX) implant (Ozurdex) under ultrasound biomicroscopy (UBM) guidance.

Case presentation

A previously healthy 8-year-old boy with a history of long-term close contact with dogs complained of blurring of vision in the right eye for a year. Ophthalmic examination of his right eye showed chronic uveitis. Notably, UBM examination identified granulomas and peripheral vitreous strand in the ciliary body from 3 to 8 o'clock positions. Enzyme-linked immunosorbent assay (ELISA) results of the intraocular fluid (IF) and serum showed increased anti-Toxocara immunoglobulin G (IgG) levels, leading to a diagnosis of peripheral granulomatous OT in the right eye. Intraocular surgery was not indicated in this case. The treatment goal was to alleviate uveitis, improve visual acuity, and prevent complications. He was treated with an intravitreal injection of DEX implant, administered as a single dose every three months, total two doses, combined with albendazole, an oral anthelmintic. Under preoperative UBM guidance, two injections were performed at the 12 and 10 o'clock positions in the pars plana where there were no granulomas and peripheral vitreous strand, successfully preventing complications associated with intravitreal injection. After two injections, the patient's right eye vision improved significantly, with the best-corrected visual acuity (BCVA) increasing from 20/400 to 20/50. Vitreous opacity and retinal edema were reduced, preretinal proliferative membrane was stabilized, and no adverse events occurred.

Conclusion

UBM can accurately determine the location and extent of peripheral granulomas in OT patients, facilitating the avoidance of granulomas during intravitreal injection and preventing complications associated with intravitreal injection. Under the close follow-up and strict adherence to indications, preoperative UBM-guided intravitreal injections of DEX implant treatment for pediatric peripheral granulomatous OT are safe and effective, providing a new therapeutic option for pediatric peripheral granulomatous OT.

Non-invasive diagnostic strategy of ocular toxocariasis based on clinical features

PURPOSE

To develop a non-invasive diagnostic strategy based on the clinical manifestations of ocular toxocariasis (OT), and evaluate its sensitivity and specificity.

METHODS

Patients with unilateral OT-like lesions were enrolled retrospectively and classified into OT and non-OT groups according to the immunologic diagnosis criterion of anti-OT IgG. Nine clinical manifestations were recorded and compared between groups. Among them, the retrolental membrane (RM), branch-like vitreous strands (BVS), and retinal granulomas (RG) were the most common, which were further classified into three categories, including at least 1 out of 3 signs, at least 2 out of 3 signs, and all 3 signs positive. Diagnostic sensitivity and specificity were calculated for each strategy.

RESULTS

There were 105 immunologically confirmed patients with OT and 70 patients with non-OT uveitis/vitreoretinopathy. RG, RM, and BVS were significantly more frequent in OT patients than in non-OT patients. At least 1 of 3 signs positive strategy showed the highest sensitivity (100.0%) but the lowest specificity (62.0%). At least 2 out of 3 signs positive strategies showed 80.0% sensitivity and 94.3% specificity. All 3 signs positive strategies had the lowest sensitivity (46.7%) and the highest specificity (100.0%). The cutoff point of this revealed an area under the curve of 0.85 and a 95% confidence interval of 0.79 to 0.91.

CONCLUSION

A comprehensive strategy based on at least 2 out of 3 positive signs showed excellent sensitivity and specificity, and could serve as a non-invasive and fast screening strategy for the clinical diagnosis of OT.

A systematic review of ultrasound biomicroscopy use in pediatric ophthalmology

Ultrasound biomicroscopy (UBM) is the only available option for noninvasive, high-resolution imaging of the intricate iridociliary complex, and for anterior segment imaging with corneal haze or opacity. While these unique features render UBM essential for specific types of trauma, congenital anomalies, and anterior segment tumors, UBM imaging has found clinical utility in a broad spectrum of diseases for structural assessments not limited to the anterior intraocular anatomy, but also for eyelid and orbit anatomy. This imaging tool has a very specific niche in the pediatric population where anterior segment disease can be accompanied by corneal opacity or clouding, and anomalies posterior to the iris may be present. Pediatric patients present additional diagnostic challenges. They are often unable to offer detailed histories or fully cooperate with examination, thus amplifying the need for high-resolution imaging. This purpose of this systematic review is to identify and synthesize the body of literature involving use of UBM to describe, evaluate, diagnose, or optimize treatment of pediatric ocular disease. The collated peer-reviewed research details the utility of this imaging modality, clarifies the structures and diseases most relevant for this tool, and describes quantitative and qualitative features of UBM imaging among pediatric subjects. This summary will include information about the specific applications available to enhance clinical care for pediatric eye disease.

Clinical features of ocular toxocariasis: a comparison between ultra-wide-field and conventional camera imaging

PURPOSE

The purpose of this study is to compare the lesion detection rates of ocular toxocariasis (OT) between ultra-wide-field scanning laser ophthalmoscopy (UWF-SLO) and conventional fundus photography (CFP), and to evaluate the potential diagnostic ability of UWF-SLO in OT.

METHODS

A total of 56 patients with serological/immunological confirmed unilateral OT were enrolled. The presence of OT characteristic features included the posterior granuloma (postG), peripheral granuloma (periG), tractional retinal detachment (TRD), retinal folds (RF), and vitreous strands (VS) and was analyzed in 36 patients with UWF-SLO and 56 patients with CFP. Diagnostic tests were employed using the clinical examination as gold standard.

RESULTS

In total of the 56 OT eyes, granulomas were identified in 91.1% (51/56) of eyes, including postG in 46.4% (26/56) of eyes, periG in 41.1% (23/56) of eyes, and combined granulomas in 3.6% (2/56) of eyes. TRD, RF, and VS were found in 28.6% (16/56), 51.8% (29/56), and 83.9% (47/56) of patients, respectively. Although the specificities of the diagnosis in clinical features were similar by the diagnostic tests, the sensitivities of postG, periG, TRD, RF, and VS using UWF-SLO were 100%, 100%, 66.7%, 95%, and 81.8%, respectively, which were significantly higher those of CFP (72.2%, 31.3%, 11.1%, 55%, and 48.5%). Additionally, the extent of vitreous haze was milder graded by UWF-SLO compared to CFP (p = 0.0099).

CONCLUSIONS

The diagnostic ability of UWF-SLO was superior to CFP using clinical examination as gold standard for the ascertainment of the characteristic manifestations of OT, especially for granulomas and RF.

Imaging of toxocariasis

Several imaging modalities have now been employed to visualize the manifestations of larval Toxocara infection in hepatic, neurologic, ocular, renal, and other anatomical sites. This report reviews the usefulness and value of these individual imaging methods in diagnosis and follow-up of the different cases causing eosinophilic (granulomatous) infiltrations the liver, lungs, brain, heart, and eyes. Imaging provides a means of assisting in diagnosis and management in this infection where diagnosis by biopsy is often unlikely to capture an actual larva for the purpose of making a definitive diagnosis on the basis of larval morphology or DNA detection.

Current epidemic situation of human toxocariasis in China

Toxocariasis is a worldwide-distributed helminthic zoonosis, which mainly results from ascarid nematodes Toxocara canis and Toxocara cati. Humans become infected by accidental ingestion of infective eggs, raw or undercooked meat containing larvae. Keeping and contacting cats and dogs, and bad hygiene situations or habits are the main risk factors for Toxocara infection in China. The seroprevalence of Toxocara spp. is reported from 12.14% to 44.83%, and the overall seroprevalence in children was 12.14% in 1993 and elevated to 19.3% in 2015. Among the 103 cases reported in China during 1983-2019, ocular larva migrans (OLM), visceral larva migrans (VLM), and neural larva migrans (NLM) occupied 92.23%, 6.80%, and 0.97% of cases, respectively. The diagnosis of toxocariasis is mainly based on the history of exposure to infective eggs or larvae, clinical manifestations, laboratory examinations, and imaging studies. As most individuals who are infected with larval Toxocara, are unaware of their infections, patients with mild signs as described under covert toxocariasis (CT) can recover spontaneously, and treatment may not be necessary. Albendazole is the preferred treatment for patients with VLM; steroids, such as prednisolone combined with albendazole, are frequently used in treating patients with OLM, and surgery serves as an alternative treatment; thiabendazole is effective in treating patients with NLM. The true number of cases and prevalence of toxocariasis in China seems to be underestimated and neglected because of the lack of population-based epidemiological studies and insufficient clinical awareness of this disease, which are aspects that need to be improved by the Chinese government.

Ocular Toxocariasis: Long-Term Follow-Up and Prognosis of Patients following Vitrectomy

Purpose: To investigate the outcomes of surgical treatment in patients with ocular toxocariasis and identify prognostic factors.Methods: We retrospectively reviewed the medical records of 56 consecutive patients who underwent vitrectomy.Results: The mean follow-up was 20.7 months. Visual acuity (VA) improved in 70.4% of patients by the final visit, but VA was better than Snellen 20/70 in only 31.5% of patients. Preoperative VA was closely correlated with final VA (P = 0.001). Macular involvement was associated with final VA worse than 20/70 (P = 0.03). The most common postoperative complications were ocular hypertension (19.6%) and retinal detachment (12.5%). Seven patients (12.5%) experienced recurrent inflammation postoperatively, but no preoperative factors were associated with recurrent inflammation.Conclusion: Surgical treatment could rescue visual function in patients with ocular toxocariasis but their prognosis was unfavorable. Preoperative VA was associated with final VA, whereas macular involvement was associated with poor visual outcomes.

Toxocariasis: a silent threat with a progressive public health impact

Background

Toxocariasis is a neglected parasitic zoonosis that afflicts millions of the pediatric and adolescent populations worldwide, especially in impoverished communities. This disease is caused by infection with the larvae of Toxocara canis and T. cati, the most ubiquitous intestinal nematode parasite in dogs and cats, respectively. In this article, recent advances in the epidemiology, clinical presentation, diagnosis and pharmacotherapies that have been used in the treatment of toxocariasis are reviewed.

Main text

Over the past two decades, we have come far in our understanding of the biology and epidemiology of toxocariasis. However, lack of laboratory infrastructure in some countries, lack of uniform case definitions and limited surveillance infrastructure are some of the challenges that hindered the estimation of global disease burden. Toxocariasis encompasses four clinical forms: visceral, ocular, covert and neural. Incorrect or misdiagnosis of any of these disabling conditions can result in severe health consequences and considerable medical care spending. Fortunately, multiple diagnostic modalities are available, which if effectively used together with the administration of appropriate pharmacologic therapies, can minimize any unnecessary patient morbidity.

Conclusions

Although progress has been made in the management of toxocariasis patients, there remains much work to be done. Implementation of new technologies and better understanding of the pathogenesis of toxocariasis can identify new diagnostic biomarkers, which may help in increasing diagnostic accuracy. Also, further clinical research breakthroughs are needed to develop better ways to effectively control and prevent this serious disease.

Electronic supplementary material

The online version of this article (10.1186/s40249-018-0437-0) contains supplementary material, which is available to authorized users.