Successful Treatment of Corneal Larva Migrans by Nd:YAG Laser Photodisruption.

PRESENTATION

An eight-year-old girl presented with a one-week history of redness in the right eye. Best corrected visual acuity was 6/6 bilaterally. The right eye showed mild circumcorneal congestion and a worm in the central cornea [Figure 1], which showed a wiggling motility under high magnification of slit lamp. The rest of the ocular examination was normal. Considering the very central location of the worm in cornea, any intervention to remove or destroy the worm was deferred on that day. By the next day, the worm had migrated to the peripheral cornea at the 10 o’clock position [Figure 2]. We decided on Nd: YAG laser photodisruption of the worm, rather than its surgical removal.

Figure 1

The cornea of the right eye showing a worm in the central location with coiling near one end.

Figure 2

The cornea of the same eye in which the worm has migrated to a peripheral position.

Laser parameters of 1 mJ and single pulse delivery were selected. The focal point of the aiming beam was set directly at the focal point of the laser disruption. After careful counseling and topical anesthesia with 0.5% proparacaine eye drops, an Ocular Abraham Iridectomy lens (Product Code: OAIY, Ocular instruments, Bellevue, Washington, USA) was applied to the ocular surface with coupling fluid. The laser was applied to both ends of the worm because it was not possible to distinguish between the head and tail ends. Two bursts of laser were directed at each end by carefully focusing the aiming beam [Figure 3]. Steroid eye drops were prescribed after the procedure and tapered slowly over two months. There was no further shift in position of the worm; over subsequent days, the worm became densely opaque and white and later disintegrated, as evidenced by the breaking up of the worm along its entire length [Figure 4]. The surrounding cornea developed white patches of stromal haze due to the inflammation following the death of the worm.

Figure 3

Laser marks at the ends of the worm.

Figure 4

One week after the laser application the worm is opaque and disintegrating.

After two months, the girl was well, with 6/6 vision and patches of stromal opacities at and around the location of the dead worm [Figure 5].

Figure 5

Two months after the laser application. The worm has disintegrated, leaving behind stromal opacities.

DISCUSSION

There are many reports of larva migrans affecting the retina, anterior chamber, or vitreous cavity from various parts of the world.[12] However, corneal worms are very rarely encountered, and management options include surgical removal or laser destruction of the worm.[345]

Only a single case of worm in the cornea was reported to have been managed by laser treatment prior to this case.[5] Surgery was not selected because of the following anticipated disadvantages: identifying the exact depth at which the worm is located within the corneal stroma would be difficult under the diffuse illumination of an operating microscope; and lack of contrast of the worm with the corneal lamella. Hence, we decided to proceed with laser destruction of the worm, which was successful. However, the patient developed stromal opacities despite steroid application. Laser destruction of the worm can be considered as a suitable option for managing corneal worms located away from the visual axis.

Financial Support and Sponsorship

Nil.

Conflicts of Interest

There are no conflicts of interest.