Fig. 3.6 Mode B ultrasonography showing an intravitreal cysticercus. Note the hyperreflective walls, hyporeflective interior, and the hyperreflective eccentric structure that corresponds to the scolex (Courtesy of Dr. Eduardo Moragrega Adame)

Fig. 3.7 Subretinal cysticercus. Mode A ultrasonography shows three high-reflective spikes that correspond to the retina, anterior and posterior wall of the cyst. An additional 100% reflectivity spike is seen inside the cyst, representing the scolex (Courtesy of Dr. Eduardo Moragrega Adame)

Treatment

Medical treatment with albendazole and praziquantel generally is used for central nervous system cysticercosis [37]. They lack efficacy, however, in the treatment of the ocular form of the disease, as reported by Santos et al. in 1984 [38]. Other authors suggest that oral treatment besides being ineffective hastens progression of the disease by exacerbating the inflammatory response [39].

Diathermy, cryotherapy [40], and photocoagulation [41, 42] are useful methods of destroying the cysticercus. They are rarely used because of the risk of eliciting severe inflammation resulting from the release of toxins from the necrotic cysticercus [22]. Currently, the treatment of choice is the surgical removal of the cysticercus.

Surgical Technique

Removal of the parasite, clearing the vitreous cavity, and removing vitreous membranes are the purposes of the surgery. Once the parasite is dead (cystic lesions without movement seen), the extraction of the cysticercus is not recommended because inflammatory responses associated with parasite death produce multiple adherences, complicating its removal [24]. The best approach to remove a free-floating cysticercus in the vitreous cavity is a pars plana vitrectomy. The vitrectomy is performed around the parasite until it is fully liberated. Then, one sclerotomy is widened according to its size, and the cyst is removed with a passive suction silicon tip probe, avoiding rupture and subsequent toxin release [24].

If the cyst is located in the subretinal space, a complete vitrectomy with a complete posterior vitreous detachment should be achieved. A retinotomy next to the location of the cyst in the temporal side of the macula is performed. The cyst is then removed, with the use of an extrusion soft-tip cannula, from the subretinal space and out of the eye through one of the sclerotomies. The retinotomy is not sealed with laser, in our experience, unless it is large or located in the periphery. Some authors, such as Pavan [43], do prefer sealing the retinotomy with laser.

The procedure is followed by an air-fluid exchange, and the patient is positioned facedown [24, 44].

Controversies and Perspectives

After the ocular cysticercus is removed, a complete work-up for T. solium infestation and neurocysticercosis should be addressed. Controversy

Fig. 3.8 (a) Image of an intraocular cysticercus located at the optic nerve producing a retinal detachment. (b) Enlarged view of cysticercus scolex. (c) Fibrous capsule encircling an eosinophilic mass with some parasitic

elements, surrounded by a polimorphonuclear infiltrate and a layer of granulomatous-type inflammatory response (Courtesy of Abelardo A. Rodríguez-Reyes, M.D. and Alfredo Gómez Leal, M.D.)

Fig. 3.9 Gross specimen shows a retinal detachment, lens opacification, inflammatory process in the vitreous cavity, cyclitic membrane, iris atrophy with anterior synechiae closing the anterior chamber angle, and partial atrophy of the ciliary body (Courtesy of Abelardo A. Rodríguez-Reyes, M.D. and Alfredo Gómez Leal, M.D.)

over the use of antiparasitic drugs (albendazole or praziquantel) still exists. Even though antihelminthic drugs do reach the CNS and effectively attack the living cysticercus, damage due to the location

of the cyst and local inflammation may be irreversible. For calcified cysts with no living parasite, antihelminthic drugs may be ineffective. In patients with viable lesions, evidence from trials suggests albendazole may reduce the number of lesions. In trials of nonviable lesions, seizure recurrence was substantially lower with albendazole treatment. Steroids may reduce headaches during treatment and probably toxin-related inflammation, but further research is needed to test this [45].

Focal Points

It is important to consider the following guidelines during surgery [46]:

•A vitrectomy or vitrectomy lensectomy is advisable whenever the vitreous or the lens is opaque.

•A vitrectomy is indicated to liberate retinal traction or macular folds.

•A scleral buckle is performed in the presence of rhegmatogenous retinal detachment.

•A vitrectomy and scleral buckle are indicated in the presence of considerable traction.

•An inflammatory response to toxins may be present if destruction of the cyst occurs inside the eye.

•A posterior vitreous cortex removal is indicated to prevent contraction in the future.

•Topical, periocular, and even oral steroids, as well as mydriatic agents, are needed to control the inflammatory response after the surgery.

Every case of intraocular cysticercosis repre-

sents a poor visual prognosis. If the parasite is located in the vitreous cavity or the subretinal space and it is not removed, a loss of visual function ensues after a period of 3–5 years [47]. In the absence of treatment, the cysticercus may increase in size, release toxins, and provoke an intense inflammatory reaction that eventually destroys other ocular structures.

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