A new worm infiltrating the human cornea: A report of three cases

Abstract

Purpose: To characterize a new species of parasitic nematode that triggers uveitis.

Observations: Three previously healthy, relatively young people each contracted a corneal stromal nematode that, upon surgical removal and examination, did not match any known nematodes. Clinical ocular findings included corneal opacification, visible corneal worms, conjunctival injection, and uveitis.

Conclusions and importance: The three cases presented here represent a previously undescribed parasitic infection of the cornea by an unidentified nematode. These findings may represent a previously unrecognized zoonotic infection from wildlife sources and potentially a newly documented nematode requiring description. Future clinical findings regarding this newly described nematode are needed to further develop our understanding of the disease.

Keywords: Cornea; Nematode; Ocular; Parasite; Stroma; Uveitis.

Fig. 1

Intrastromal haze and poorly visible worm inferiorly (circled) in Case 3. There is diffuse epithelial haze extending to the anterior stroma with 2–3+ central endothelial keratic precipitates. Inferiorly in the mid-peripheral stroma, a 1 mm long and very thin translucent motile worm is poorly visible.

Fig. 2

Scheimpflug showing the depth of the intrastromal worm in Case 3.

Fig. 3

Entire worm in Case 3. An intact white translucent adult male nematode measuring 1,050 μm in length and 90 μm in diameter with slightly tapered ends, visualized by microscope.

Supplemental Fig. 1

Intrastromal corneal worm in Case 1. A 1.5 mm long translucent motile worm located approximately ⅔ depth within the mid-periphery of the corneal stroma is visible.

Supplemental Fig. 2

Evidence of intrastromal inflammation in Case 2. The cornea shows diffuse subepithelial opacities from the 11:00 limbus to 2:30, with surrounding cell.

Supplemental Fig. 3

Slit lamp exam showing worm in Case 3. A clearer image of the 1 mm long, thin translucent motile worm upon slit lamp exam.

Supplemental Fig. 4

Surgical view of worm visible on retro-illumination in Case 3. The patient was dilated preoperatively in order to improve visualization against a red reflex.

Supplemental Fig. 5

Worm on the forceps in Case 3. The worm was removed after a precise trephination and partial lamellar dissection above the depth of the worm.

Supplemental Fig. 6

Striated cuticle of worm in Case 3. The worm was uniform in diameter, and had a thick, finely striated cuticle measuring 2 μm in width.

Supplemental Fig. 7

Anterior tip of worm in Case 3 demonstrating mouth and cuticular-lined esophagus.

Supplemental Fig. 8

Anterior of worm in Case 3. A cuticular-lined esophagus occupies about 1/3 of the worm's length in Case 3.

Supplemental Fig. 9

Esophageal-intestinal junction of worm in Case 3.

Supplemental Fig. 10

Intestine of worm in Case 3 measuring 35 μm in diameter.

Supplemental Fig. 11

Two unequal dissimilar spicules at posterior end of worm in Case 3.