Referral to an ophthalmologist is indicated if symptoms are still present at 12 months, or sooner if significant symptoms or recurrent infections occur. Nasolacrimal duct probing may be performed in the office setting (usually from 4 to 8 months of age) or under general anesthesia in an operating room for older patients. The success rate of probing is higher for younger children. A silastic tube or stent may be employed along with probing to maintain tear duct patency. A systematic review comparing immediate probing with deferred probing found that in children with unilateral nasolacrimal duct obstruction, immediate probing resulted in a higher success rate of treatment compared to deferred probing. Diagnosis
Evaluation is in the form of a dye disappearance test followed by irrigation test. By using this sequence (with modifications) as a guide, the physician can frequently streamline diagnostic testing. Dye disappearance test
The dye disappearance test is useful for assessing the presence or absence of adequate lacrimal outflow, especially in unilateral cases. It is more heavily relied upon in children, in whom lacrimal irrigation is impossible without deep sedation. Using a drop of sterile 2% fluorescein solution or a moistened fluorescein strip, the examiner instills fluorescein into the conjunctival fornices of each eye and then observes the tear film, preferably with the cobalt blue filter of the slit lamp. Persistence of significant dye and, particularly asymmetric clearance of the dye from the tear meniscus over a 5-minute period indicate an obstruction. If the dye disappearance test result is normal, severe lacrimal drainage dysfunction is highly unlikely.
Epidemiology
Areas with the highest prevalence of helminthiasis are tropical and subtropical areas including sub-Saharan Africa, central and east Asia, and the Americas. Neglected tropical diseases
Some types of helminthiases are classified as neglected tropical diseases. They include:

Soil-transmitted helminthiases
Roundworm infections such as lymphatic filariasis, dracunculiasis, and onchocerciasis
Trematode infections, such as schistosomiasis, and food-borne trematodiases, including fascioliasis, clonorchiasis, opisthorchiasis, and paragonimiasis
Tapeworm infections such as cysticercosis, taeniasis, and echinococcosis

Prevalence
The soil-transmitted helminths (A. lumbricoides, T. trichiura, N. americanus, A. duodenale), schistosomes, and filarial worms collectively infect more than a quarter of the human population worldwide at any one time, far surpassing HIV and malaria together. Schistosomiasis is the second most prevalent parasitic disease of humans after malaria.In 2014–15, the WHO estimated that approximately 2 billion people were infected with soil-transmitted helminthiases, 249 million with schistosomiasis, 56 million people with food-borne trematodiasis, 120 million with lymphatic filariasis, 37 million people with onchocerciasis, and 1 million people with echinococcosis. Another source estimated a much higher figure of 3.5 billion infected with one or more soil-transmitted helminths.In 2014, only 148 people were reported to have dracunculiasis because of a successful eradication campaign for that particular helminth, which is easier to eradicate than other helminths as it is transmitted only by drinking contaminated water.Because of their high mobility and lower standards of hygiene, school-age children are particularly vulnerable to helminthiasis. Most children from developing nations will have at least one infestation.