Journal of Pediatric Ophthalmology and Strabismus

Ocular Cysticercosis in India

Dhan Krishna Sen, MS; Hari Mohan, FRCS

Abstract

Human cysticercosis is probably always due to infestation with Cysticercus cellulosae, the larval form of Taenia Solium.1 Ocular cysticercosis appears to be a disease of the young. All the cases in the present series were within 20 years of age. The adult tape worm lives in the small intestine of man, the definitive host. The intermediate host, usually the pig, ingests the eggs (ova) present in the excreta of an infested person. In its stomach the egg shells are dissolved and the embryos, on being set free, penetrate the intestinal mucosa and are transported throughout the body via circulation, lodging particularly where the capillaries are narrow and the current slow, where in 2-3 months time they develop into Cysticercus cellulosae.

They are ovoid translucent bodies, measuring on the average 15x8 mm. Each consists of a hollow vesicle with an invaginated scolex on its wall which appears as a milk spot to the naked eye. The scolex has a double crown of hooklets and four disc-like suckers. Around each larva a cellular inflammatory reaction is set up and a connective tissue capsule is formed. In this state the Cysticercus may live for years. The life cycle is completed by ingestion of the viable Cysticercus in insufficientlycooked or raw infected pork by man. On reaching the intestine the Cysticercus fixes its scolex to the intestinal wall and gradually grows to become the adult tape worm and the cycle repeats itself. Occasionally the man may become the intermediate host by ingesting the eggs present usually in conta miriated food or water and occasionally through autoinfection from unclean personal habits (anus to mouth transmission) or by reverse peristalsis into the stomach. Thereafter the sequence of events are the same as those occurring in the pigs.

PRESENT STUDY

We came across 22 cases of ocular cysticercosis over a period of 18 years in the eye department of Irwin Hospital, New Delhi. Age and sex distribution of the cases, side involved, and the localization of the cyst in the eye are given in Table I. Only one eye was involved in all the cases and there was only one cyst in the eye.

In subconjunctival cysticercosis (14 cases), the different clinical forms seen were:

1. Cyst without any clinical signs and symptoms of inflammation (9 cases) - The cyst was painless on pressure. There was no clinical evidence of any inflammatory reaction around the cyst. The patients reported to the hospital only because of cosmetic disfigurement in the white of the eye. In two patients the swelling was quite firm to feel and appeared more like a small subconjunctival nodule rather than a cyst.

2. Chronic subconjunctival abscess (2 cases) - One patient presented as a fluctuant swelling adherent to both conjunctiva and the globe, moderately painful on pressure with localized congestion. Pus welled out along with a Cysticercus when the abscess was evacuated. The second case presented as a tender nonfluctuant swelling fixed to the globe. When the mass was excised and cut open a small Cysticercus was seen lying in a pool of pus.

3. Acute subconjunctival abscess (1 case) - It presented with signs of acute suppurative inflammation with pus pointing at one point. When a nick was made on the abscess, pus along with a Cysticercus escaped.

4. Recurrent conjunctival inflammation (1 case) - It presented with recurrent attacks of inflammation limited to the lateral fornix. A small cystic swelling appeared under the conjunctiva subsequently.

Table

Subconjunctival cysticerci were frequently lodged in close relation to the sheath of rectus muscles near their insertions which indicates that they probably reach the site via…

Human cysticercosis is probably always due to infestation with Cysticercus cellulosae, the larval form of Taenia Solium.1 Ocular cysticercosis appears to be a disease of the young. All the cases in the present series were within 20 years of age. The adult tape worm lives in the small intestine of man, the definitive host. The intermediate host, usually the pig, ingests the eggs (ova) present in the excreta of an infested person. In its stomach the egg shells are dissolved and the embryos, on being set free, penetrate the intestinal mucosa and are transported throughout the body via circulation, lodging particularly where the capillaries are narrow and the current slow, where in 2-3 months time they develop into Cysticercus cellulosae.

They are ovoid translucent bodies, measuring on the average 15x8 mm. Each consists of a hollow vesicle with an invaginated scolex on its wall which appears as a milk spot to the naked eye. The scolex has a double crown of hooklets and four disc-like suckers. Around each larva a cellular inflammatory reaction is set up and a connective tissue capsule is formed. In this state the Cysticercus may live for years. The life cycle is completed by ingestion of the viable Cysticercus in insufficientlycooked or raw infected pork by man. On reaching the intestine the Cysticercus fixes its scolex to the intestinal wall and gradually grows to become the adult tape worm and the cycle repeats itself. Occasionally the man may become the intermediate host by ingesting the eggs present usually in conta miriated food or water and occasionally through autoinfection from unclean personal habits (anus to mouth transmission) or by reverse peristalsis into the stomach. Thereafter the sequence of events are the same as those occurring in the pigs.

PRESENT STUDY

We came across 22 cases of ocular cysticercosis over a period of 18 years in the eye department of Irwin Hospital, New Delhi. Age and sex distribution of the cases, side involved, and the localization of the cyst in the eye are given in Table I. Only one eye was involved in all the cases and there was only one cyst in the eye.

In subconjunctival cysticercosis (14 cases), the different clinical forms seen were:

1. Cyst without any clinical signs and symptoms of inflammation (9 cases) - The cyst was painless on pressure. There was no clinical evidence of any inflammatory reaction around the cyst. The patients reported to the hospital only because of cosmetic disfigurement in the white of the eye. In two patients the swelling was quite firm to feel and appeared more like a small subconjunctival nodule rather than a cyst.

2. Chronic subconjunctival abscess (2 cases) - One patient presented as a fluctuant swelling adherent to both conjunctiva and the globe, moderately painful on pressure with localized congestion. Pus welled out along with a Cysticercus when the abscess was evacuated. The second case presented as a tender nonfluctuant swelling fixed to the globe. When the mass was excised and cut open a small Cysticercus was seen lying in a pool of pus.

3. Acute subconjunctival abscess (1 case) - It presented with signs of acute suppurative inflammation with pus pointing at one point. When a nick was made on the abscess, pus along with a Cysticercus escaped.

4. Recurrent conjunctival inflammation (1 case) - It presented with recurrent attacks of inflammation limited to the lateral fornix. A small cystic swelling appeared under the conjunctiva subsequently.

Table

TABLE IDISTRIBUTION OF 22 CASES OF OCULAR CYSTICERCOSE SEEN IN THIS HOSPITAL

TABLE I

DISTRIBUTION OF 22 CASES OF OCULAR CYSTICERCOSE SEEN IN THIS HOSPITAL

5. Epibulbar tumor (1 case) - It presented as a gradually growing noninflammatory greyish white smooth globular mass, firm to feel. On surgical exposure it appeared to arise from the sclera. It was dissected out from the surrounding structures and shaved off from the sclera. On cutting open the tumor mass a Cysticercus was seen lying inside.

In all the patients the cyst was surgically removed. In 10 out of 14 patients the cyst was found embedded in Tenon's capsule in relation to the sheath of one of the rectus muscles near its insertion. The diagnosis was confirmed by histopathological examination in every case. The connective tissue capsule formed by the tissue reaction showed infiltration with varying degree of inflammatory cells. The nature of inflammatory reaction was variable and can be grouped under acute suppurative, chronic suppurative, chronic nongranulomatous, and granulomatous reactions. The larval body in the section was characterized by its tortuous lumen, its suckers, and its hooklets.

In lid cysticercosis (2 cases), the different clinical forms seen were:

1. Nodule in the orbicularis - The case presented with the complaint of feeling a small hard nodule while passing fingers over the closed left upper lid. It was painless on pressure and felt like a lead pellet. On surgical exposure the nodule was found embedded in the fibers of orbicularis oculi muscle. It was excised and the diagnosis was established by histopathological examination.

2. Subcutaneous nodule - A small nodule was found in the subcutaneous tissue just below the left eye brow. It was also excised. The diagnosis was established by histopathological examination.

In orbital cysticercosis (3 cases), the different clinical forms seen were:

1. Simple ptosis - The case initially reported with simple ptosis. There was no other clinical finding. General physical examination and a complete neurological work up were noncontributory. All special investigations were negative. Eight months later the child presented with acute orbital cellulitis which progressed on to abscess formation. While draining the pus through the upper fornix, a typical Cysticercus cyst escaped.

Table

TABLE IIDISTRIBUTION OF 134 CASES OF OCULAR CYSTICERCOSE (INCLUDING THE PRESENT SERIES) RECORDED IN INDIA

TABLE II

DISTRIBUTION OF 134 CASES OF OCULAR CYSTICERCOSE (INCLUDING THE PRESENT SERIES) RECORDED IN INDIA

2. Acute orbital abscess - This case presented initially as acute orbital abscess in the upper and inner quadrant. The Cysticercus escaped during the drainage of pus.

3. Painless cyst - The cyst was found near the upper and outer orbital margin in close relation to the palpebral portion of the lacrimal gland. There was no signs of any inflammatory reaction around it. It was accidentally discovered during a routine check up and excised.

The diagnosis was confirmed by histopathological examination in all the cases.

In intraocular cysticercosis (3 cases) - the different clinical forms seen were:

1. Free floating vitreous cyst - The cyst was globular and translucent with a sharp luminous border. Frequent wave-like undulating movements were seen which were accentuated by throwing light on the cyst. A white spot on the surface of the cyst represented the scolex. An attempt to remove the cyst surgically through a posterior scleral route ended in failure and the patient was lost to further follow up,

2. Panuveitis - The case presented with hypopyon and lots of vitreous exudates, With heavy doses of steroids and other supportive therapy the vitreous became clearer and a globular translucent cyst was seen lying in the vitreous. The diagnosis was made by observing the characteristic movements of the scolex. The inflammatory changes in the posterior segment were gross and the projection of light rays was inaccurate. Since the visual prognosis was very poor the parents of the child refused surgery. The patient was brought back after a period of four years when on examination the eye was found to be phthisical.

3. Migratory white mass in the fundus - The case presented with a greyish white mass, one-fourth disc diameter across, in the upper and outer quadrant. Admission to the hospital was advised for investigations but the patient refused. He reported back after two months when on examination the mass was found to have changed its position to occupy the lower and outer quadrant and it appeared larger and more globular. The subretinal cyst was alive and active. A diagnosis of a parasitic cyst was made. It was accurately localized and removed through the posterior scleral route with the help of an erisiphake. The diagnosis was confirmed by histopathological examination. Postoperatively vision remained unaffected.

DISCUSSION AND COMMENTS

Taenia solium infestation had a world-wide distribution and used to be seen in a section of the population with a lowsocioeconomic status and poor personal hygiene. The situation has changed today and the condition has become unusual in most western countries. However, the present series illustrate that this parasitic disease still remains a problem in an underdeveloped country like India. Therefore, the condition has to be kept in mind in the differential diagnosis of acute or chronic eye conditions affecting Indians, especially since the presentation of ocular cysticercosis is so varied.

Fig. 1. Case showing acute subconjunctival Cysticercus abscess in the media/ quadrant of left eye.

Fig. 1. Case showing acute subconjunctival Cysticercus abscess in the media/ quadrant of left eye.

Fig. 2. Case showing chronic subconjunctival Cysticercus abscess in the lower fornix of left eye.

Fig. 2. Case showing chronic subconjunctival Cysticercus abscess in the lower fornix of left eye.

Fig. 3. A small subconjunctival cyst in the lateral quadrant of left eye. Appearance of the cyst was preceded by localized recurrent conjunctival inflammation.

Fig. 3. A small subconjunctival cyst in the lateral quadrant of left eye. Appearance of the cyst was preceded by localized recurrent conjunctival inflammation.

Fig. 4. Section showing the body of a larva removed from under the conjunctiva. The membrane around the central cavity shows typical gland-shaped convolutions (hematoxylin and eosin, original magnification x 60).

Fig. 4. Section showing the body of a larva removed from under the conjunctiva. The membrane around the central cavity shows typical gland-shaped convolutions (hematoxylin and eosin, original magnification x 60).

The condition is more prevalent in the southern part of India, where the economic status of the rural population is lower and the personal hygiene poorer. Out of the 1 12 cases of ocular cysticercosis previously reported from India 80 were from the South. Table II gives the distribution of all the cases so far recorded from India including the present series. It may be seen that young people were most commonly affected and there was no sex predilection. Cysticercosis is a systemic disease and the cysticerci are found most frequently in the brain, eye, and subcutaneous tissue, and less frequently in the heart, skeletal muscles, liver, and lungs. It is surprising that along with eye involvement other systems in the body were very rarely involved. There were only five such cases out of a total of 134. It is also interesting to know that the left eye was more frequently affected. This is probably due to the fact that the left internal carotid artery takes off from the aorta in direct line with the direction of the blood flow in the aorta. In the eye the Cysticercus can get lodged in any part, but subconjunctival localization has been found to be most common in India (92 cases out of a total of 134, constituting 68.6%), where as intraocular localization has been found to be most common in western countries.2-6

Fig. 5. Showing a free floating intravitreal cyst.

Fig. 5. Showing a free floating intravitreal cyst.

Subconjunctival cysticerci were frequently lodged in close relation to the sheath of rectus muscles near their insertions which indicates that they probably reach the site via the anterior ciliary arteries. The site of lodgment of these cysts in the subconjunctival tissue in order of frequency Were medial, lower, lateral, and upper quadrant. The preference for the' medial quadrant may be because of the anatomical course of the ophthalmic artery which runs along the medial side of the orbit and divides into its terminal branches. The most common mode of presentation of subconjunctival cysticercosis was in the form of painless, hemispherical swelling without any clinical evidence of inflammation around the cyst. This is contrary to Duke-Elder's statement that these cysts are usually adherent to the sclera and are painful on pressure and therefore may be differentiated from hydatid cysts which excite no inflammatory reaction. On the other hand, in cases of ocular cysticercosis inflammatory reaction, when present, may be so severe as to give rise to acute abscess or may be so chronic as to give rise to a fibrous mass that simulates an epibulbar tumor.

In the sections made from the tissue specimens the inflammatory reaction, when present, was seen to surround the larva. In no case was the larval body invaded by the inflammatory cells. However, this may be expected to occur following the death of the larva when the disintegration process commences. Calcification of the larva may eventually occur, but no such case of ocular cysticercosis has been recorded from India.

Orbital affection is rare8 and in cases where it occurs the site is near the orbital margin. particularly above or below near the inner side, and only very rarely in the depths of the orbit. The sequence of events of one case seen by us was unique. The patient initially reported with simple ptosis, the cause of which could not be established. The diagnosis became apparent only after a period of eight months when the child reported back with the development of acute orbital cellulitis which progressed into orbital abscess and it was drained. Lid affection is exceptionally rare.7 There has been only one case record in the recent world literature.6 However, in our series of 22 cases we came across two cases. One of them appears to be the first case where the Cysticercus has been found tobe embedded in the fibers of orbicularis oculi muscle.

Cases of intraocular cysticercosis usually present with gradually increasing, painless diminution of vision. In the early stages when the parasite presents as a small greyish white mass, any evidence of its migration should arouse strong suspicion of a subretinal Cysticercus, and a careful, repeated examination is Indicated to follow-up the development. Intraocular Cysticercus cyst elicits gross inflammatory changes which may lead to extensive chorioretinitis, uveitis, exudative retinal detachment, retinal hemorrhages and retinitis proliferans, complicated cataract and eventual disorganization of the intraocular structures leading to a phthisical globe. Cyst in the anterior chamber appears like a pearl and may show heaving movements.

The presence of gravid segments or eggs of tenia solium in the feces of the patients, eosinophllia in the differential leucocyte count, positive complement fixation test for this parasite, and calcification of the cystradiologically are some of the supporting findings used in the diagnosis of ocular cysticercosis. However, out of 134 cases, history of having eaten pork was available only in eight patients, stool was positive in four patients and eosinophilia was present in five patients. They are, therefore, of not much value in the diagnosis of ocular cysticercosis. A diagnostic puncture of the anterior chamber for aqueous eosinophile count has been suggested in cases in which an intraocular Cysticercus is suspected.9

Complete surgical removal of the cyst at the earliest opportunity in subconjunctival, lid, and orbital cases gives permanent relief. However, excision may be difficult where adhesions exist. In cases of subconjunctival and orbital abscess, pus along with the cyst is evacuated. On the otherhand, removal of an intraocular Cysticercus cyst is problematic. Arruga10 stated that even with successful extraction of the cyst, inflammatory complications in the uvea are frequent and sometimes the end result is retinal detachment or atrophy of the eye ball. This is true in most cases of intravitreal cysticercosis because of the hazards in its surgical removal. However, subretinal cysticercosis carries a better prognosis if the cyst is detected and removed early, i.e., before the retina suffers extensive damage. For removal of a subretinal cyst accurate localization is essential. A lateral canthotomy and division of the lateral rectus muscle with maximal rotation of the globe medially may have to be done to increase exposure of the back of the eye.4'5

In cases where the Cysticercus is lodged in or near the posterior pole of the eye a more extensive approach like a Kronlein procedure may be required to attain adequate access to the site." In most occasions when the lips of the scleral wound are pulled apart the cyst presents into the wound either by itself or by gentle pressure on the globe. In case it fails, application of negative pressure with the help of an erisiphake or by applying the tip of a glass tube attached to a rubber bulb may help in the removal of the cyst. Destruction of subretinal Cysticercus without removing it from the eye by methods such as diathermy, photocoagulation, or irradiation has been advocated but it usually results in release of toxins and loss of the eye.12 However, they may be successful if the cyst is very small. Cryoapplication may also be successful in such cases.5 A common method for removal of intravitreous cyst is by an open approach with lens extraction13; but massive, uncontrolled loss of vitreous and fragmentation of the parasite without complete delivery are distinct possibilities with this method. A pars plana approach using a cryoprobe14 may be a safer procedure. Recently pars plana vitrectomy was used for the removal of a intravitreous cyst with minimal damage to the eye.15

SUMMARY

Twenty-two cases of ocular cysticercosis have been studied. All of the patients were under 20 years of age. Only one eye was involved in all the patients and there was only one cyst in the eye. Fourteen of the cases were subconjunctival. Most of the subconjunctival cases presented as a painless cyst; others presented as acute or chronic abscess, recurrent conjunctival inflammation, or epibulbar tumor. Orbital cases (3) presented as simple ptosis, abscess, or a painless cyst. Of the two lid cases one presented as a nodule in the orbicularis muscle and the other as a subcutaneous nodule. Of the intraocularcasesone presented as a free floating vitreous cyst, another as panuveitis, and the remaining one as a migratory white mass in the fundus. In all but two cases the diagnosis was confirmed by histopathological examination. Complete surgical removal of the cyst or evacuation of a Cysticercus abscess at the earliest opportunity in extraocular cases gave permanent relief. Removal of intraocular cysticercosis is problematic. Different surgical methods have been reviewed. Subretinal cysticercosis was found to carry a better prognosis if the cyst was detected and removed early.

Distribution of 134 cases recorded from India, including the present series, have been analyzed in detail. Ocular cysticercosis was found to be more common in the south. The involvement of other systems in the body along with the eye was exceptionally rare. The left eye was more commonly affected. The most common site of lodgment of Cysticercus in the eye was subconjunctival and the medial quadrant was the most preferred site.

REFERENCES

1. Swellengrebel NH, Sterman MM: Animal Parasites in Man. Princeton, New Jersey, D. Van Nostrane! Co., 1961, pp 242-259.

2. Duke-Elder S: Diseases of the outer eye. In Duke-Elder S (ed): System of Ophthalmology, Vol. 8 Part I. London, Henry Kimpton, 1965, pp 423, 425.

3. Duke-Elder S, Perkins ES: Diseases of the uveal tract. In Duke Elder S (ed): System of Ophthalmology, Vol. 9. London, Henry Kimpton, 1966, pp481.

4. Segal P, Mrzyglod S, Smolacz-Dudavawicz J: Subretinal cysticercosis in the macular region. Am J Ophthalmol 57:655, 1964.

5. Bartholomew RS: Subretinal cysticercosis .Am J Ophthalmol 79:670, 1975.

6. Jampol LM, Caldwell JBH, Albert DM: Cysticercus cellulosae in the eye lid. Arch Ophthalmol 89:319-320, 1973.

7. Duke-Elder S, MacFaul PA: The ocular adnexa. in Duke-Elder S (ed): System of Ophthalmology, Vol. 13, Part I. London, Henry Kimpton, 1974, p 195.

8. Duke-Elder S, MacFaul PA: The ocular adnexa. In Duke-Elder S (ed): System of Ophthalmology, Vol. 1 3, Part II. London, Henry Kimpton, 1 974, pp 929, 930.

9. Manschot WA: Intraocular Cysticercus. Arch Ophthalmol 80:772, 1968.

10. Arruga H: Ocular Surgery, 3rd ed. Barcelona, Salvat Editors, 1 962, ? 876.

11. Brück AJ: The applicability of the Kronlein operation for the removal of Cysticercus of the posterior half of the eye. Arch Ophthalmol 13:1042, 1935.

12. Lech J: Ocular cysticercosis. Am J Ophthalmol 32:523, 1949.

13. Barraquer J: Lens extraction and extraction of Cysticercus (film presentation). American Academy of Ophthalmology and Otolaryngology Meeting, October 23, 1963.

14. Shea M, Maberley AL, Walters J et al: Intraocular taenia crassiceps (cestoda). Trans Am Acad Ophthalmol Otolaryngol 77:778, 1973.

15. Hutton WL, Vaiser A, Snyder WB: Pars plana vitrectomy for removal of intravitreous Cysticercus. Am J Ophthalmol 81:571, 1976.

TABLE I

DISTRIBUTION OF 22 CASES OF OCULAR CYSTICERCOSE SEEN IN THIS HOSPITAL

TABLE II

DISTRIBUTION OF 134 CASES OF OCULAR CYSTICERCOSE (INCLUDING THE PRESENT SERIES) RECORDED IN INDIA

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