Linguatula serrata in the anterior chamber of the eye.

We report a case of intraocular Linguatula in healthy young female who presented with a history of trivial trauma, dislocated lens, inflammation and secondary glaucoma. A mobile worm was seen in the anterior chamber. Pars plana lensectomy and vitrectomy was planned to remove both the cataractous lens and the parasite during which the worm disappeared from view but was later recovered from the cassette fluid. It was identified as the nymphal form of Linguatula serrata (tongue worm).

Tongue worm (Linguatula serrata) is an endoparasite commonly dwelling in carnivores, especially dogs. Humans are intermediate incidental hosts and dead end for the parasite.[1] Ocular manifestation is extremely rare. We hereby report a live tongue worm in the eye and its removal.

Case Report

A 25-year-old Asian Indian female, from agricultural background in rural south India visited our hospital with blunt injury to right eye (RE) followed by diminution of vision, pain, redness and watering. She was already on topical and oral steroids, cycloplegics and anti-glaucoma medications (including acetazolamide). Her past and medical history was unremarkable. On examination, best corrected visual acuity (BCVA) was 20/120, N36 in RE and 20/20, N6 in left eye (LE). Goldmann applanation tonometry was 34 and 12 mm of Hg in RE and LE respectively. Anterior segment examination of RE revealed circum-corneal congestion, microcystic corneal edema, anterior chamber (AC) reaction, dilated pupil, inferior subluxation of cataractous lens and a whitish mobile body in AC 4 mm in length showing undulating movements [Fig. 1]. The optic disc was healthy and retina attached. LE was normal. Her systemic examination was unremarkable.

Figure 1

Anterior segment photograph at presentation showing the worm in the inferior part of the anterior chamber. The dislocated lens is seen in the lower half of the pupil

A diagnosis of RE traumatic subluxation of lens with live worm in AC was made. The patient was taken up for surgical removal of the parasite with dislocated lens via pars plana route (20G) and lensectomy, vitrectomy, belt buckling with peripheral laser was done under local anaesthesia. The parasite was seen in the anterior chamber just prior to the start of surgery but had moved posteriorly by the time anesthesia was administered and the eye was prepared. 20G pars plana sclerotomies were made and lensectomy was started, during which time it was seen stuck to the posterior lens surface [Fig. 2]. The parasite then suddenly disappeared from view and could not be traced despite complete clearing of media and thorough retinal examination with scleral depression. No evidence of retinal or subretinal hemorrhages was seen to suggest subretinal passage that is known to occur with live parasites during attempted removal. The pars plana showed a small fibrotic scar which could have indicated a previous location of the parasite. On a suspicion of it being sucked into the cutter port unnoticed, the vitrectomy cassette fluid was sent to pathology lab and sedimented, the wet mount of which revealed a worm [Fig. 3] which was identified as nymphal stage of L. serrata by one of the authors (MR) who is a veterinary parasitologist.

Figure 2

Intraoperative still photograph showing the parasite on the undersurface of the lens (arrow)

Figure 3

Wet mount photograph of the worm retrieved from the cassette fluid, that was identified as Linguatula serrata (×5)

The postoperative period was uneventful. Patient was reviewed after 6 weeks with BCVA of 20/40, N6 in RE and a quiet eye [Fig. 4], normal intraocular pressure, clear vitreous cavity and an attached retina. Scleral fixated intraocular lens implantation was done 6 months after the initial surgery following which her BCVA was 20/30, N6 with quiet eye and normal posterior segment.

Figure 4

Anterior segment photograph at 6 weeks follow-up showing a quiet eye

Discussion

Tongue worm is an endoparasite dwelling in the nasopharynx of carnivores and lungs of birds and reptiles. In India approximately 38% of stray dogs are infected with the disease.[2] The colour and shape of the worm varies from species to species. They are usually colourless to yellow with no distinct body parts or shape. Females are larger in size as compared to males. Definitive hosts cast eggs in water or vegetations which are taken up by intermediate hosts, develop into nymphs (infective larvae), migrate to various organs and become encysted. Once the nymphs reach the definitive host they develop in adult worms. The parasite usually degenerates in intermediate host and there is no existing definitive antihelmenthic drug for the same.[3]

Humans get infected with the adult tongue worms. The disease is known as Halzoun syndrome[4] and Marrara disease[5] (hypersensitivity reaction to the nymphs). Patients develop symptoms due to nasopharyngeal blockage. Ocular linguatuliosis is rare. A similar presentation as to our case was reported by Deweese et al.[6] Lang et al. have described a case of iritis causing secondary glaucoma due to L. serrata.[7] A case report of occurrence of a similar worm has been described from India.[8] The patient in this report had evidence of mild iritis. Apart from L. serrata other worms that have been found in AC are filarial worms (Brugia malayi and Wuchereria bancrofti), Spirometra species (diphyllobothroid tapeworms), Schistosoma species (blood fluke), Paragonimus westermani (lung fluke), Onchocerca volvulus (river blindness nematode), Loa loa (African eye worm).

Our patient had the nymphal stage of the worm in AC and traumatic subluxation of lens with secondary glaucoma. The two findings were probably coincidental but both warranted surgical intervention. Intracameral acetylcholine can be used as an agent for chemoparalysis of worms in the AC, however in our case with subluxated lens and therefore a single chamber, we were unaware of possible safety issues such as retinal toxicity.[9] Live parasite causing sufficient inflammation to dissolve the zonules causing spontaneous subluxation of lens has not been reported and the history of trauma seems to be a reliable coincidence. The difficulties of removing a live, mobile parasite from the eye are highlighted in this case, where an easily visualized live worm disappeared from view at the start of and during surgery. Another point of interest is the fact that a larger bore (20G) vitrectomy cutter was used, which probably made it easy for the worm to pass though the lumen intact and facilitated its identification in the cassette fluid. This illustrates a novel location for a “missing intraocular parasite.”