Ocular larva migrans is a type of parasitic infection caused by larvae of toxocara canis (dog roundworm). In this condition the larvae of roundworm migrates to eyes and the optic nerve causing visual disturbance, eye pain and strabismus. Ocular parasites in humans are more prevalent in areas where there is poor sanitary condition favoring transfer of parasite between man and animals.
Toxocara is passed from cats and dog feces to human being. Infection occurs when the larvae of roundworm pass into the stomach through contaminated hands, raw or under cooked food. Usually examination of eye provides clue to the underlying disease.Treatment includes use of steroids eye drops, anti parasitic medicines, and sometimes surgery. Early detection of the condition is vital to treat the infection and reduce risk of loss of vision.
Causes Of Ocular Larva Migrans
Ocular larva migrans is a parasitic infection caused by roundworm belonging to toxocara family. The egg of toxocara canis is found in the feces of animals such as dogs and cats. It is also found in soil and products that are contaminated by feces of these animals. Transmission of the infection occurs via oral route in humans.The larvae after entering in the human intestine can travel into bloodstream. It can reach from one site to another through the bloodstream leading to inflammation and other symptoms at the site. The larvae can reach the eyes through blood producing symptoms.
Usually the infection occurs in areas with poor sanitation and hygiene. Since the roundworm is present in animals such as cats and dogs, there is increased risk among people having such pets at home. Young children who play in mud soil and outdoors may come in contact with the soil contaminated with animal feces.
The parasitic larvae may enter through oral route. Eating raw food, under cooked meat infected with the eggs of toxocara carni can also spread the infection. The infection is observed more commonly in teenagers and young adults.
Symptoms Of Ocular Larva Migrans
Ocular larva migrans mostly present symptoms pertaining to eyes. The risk factor is contact with dogs and cats, especially puppies and kittens. They have higher incidence of toxocara carni infection. In most cases the infection is only limited in one eye. Here are important symptoms of this condition:
- Pain in eyes
- Swollen eyes
- Loss of visual acuity.
- White spots in eyes.
- Sensitivity to light.
- Inflammation of the vitreous.
- Blood red conjunctiva.
- Loss of vision in affected eye.
- Edema in the macula.
- In rare case detachment of retina.
- Atrophy of optic nerve.
Some patients are diagnosed during routine eye examination as the symptoms may not be noticeable. However, in some cases there may be severe form of eye symptoms.
Treatment For Ocular Larva Migrans
Ocular larva migrans is not easy to treat. The most important aim of treatment is to prevent any further deterioration of vision and damage to eye. Detecting the disease early is beneficial to reduce the risk of loss of vision. Following are the treatment modalities:
- Topical steroid drops helps to reduce inflammation.
- In some cases steroid is injected in the area surrounding the eye (periocular space).
- Use of anti parasitic medicines.
- Surgery called vitrectomy to reduce the risk of retinal detachment. It also helps to improve the vision.