Congenital cystic eye with meningocele.

Sir,

Congenital cystic eye is a very rare condition, first described by Ida Mann in 1937 for an ocular malformation formed by a cavity lined by neuroglial tissue[12].

This is a primary developmental abnormality of the globe which presents at birth as a bluish orbital mass that usually pushes the upper lid forward[1]. It is rarely associated with intracranial anomalies or other systemic anomalies[13]. However, its association with a meningocele is extremely rare and can pose a difficult management issue to neurosurgeons.

A 2 year old boy presented with a progressively enlarging swelling in the right orbit since birth which was cystic, non tender, and trans-illuminant occupying and protruding out of the right orbit [Figure 1]. The upper eyelid was stretched and displaced forwards. The cornea and sclera were not visualized. The lesion was not compressible and there was impulse on crying. The left eye was normal.

Figure 1

Right congenital cystic eye

His MRI revealed a multiloculated cystic lesion in the right orbit with variable intensities [Figure 2A,B]. The visual apparatus could not be identified separately. The posterior cystic component was hyperintense on T2 weighted images, inverting on FLAIR and probably communicating with the intracranial CSF space through the optic foramen, suggestive of an optic nerve sheath meningocoele. The brain was not seen to be herniating into the orbit through this defect. The anterior cystic component was also hyper intense on T2 weighted images but not inverting on FLAIR. Its wall was enhancing on contrast. Brain and the opposite eye were normal. CT scan with reconstruction showed that the right bony orbit was larger than the normal left orbit with thinning of the sphenoid wing and enlargement of the superior orbital fissure and orbital foramen on this side [Figure 3].

Figure 2(A)

MRI T2W coronal images

Figure 2(B)

MRI T2W coronal images

Figure 3

CT coronal reconstruction, bone window

A clinical diagnosis of congenital cystic eye with sphenoid wing dysplasia and meningocele was made. An anterior trans-orbital approach was used to excise the orbitalcyst. The histopathological examination showed it to be a congenital cystic eye, lined by a layer of neural tissue. His postoperative recovery was complicated by profuse CSF leak through the orbit which required transcranial and transorbital repair procedures and a thecoperitoneal shunt.

Disturbance of morphogenetic pathway that controls eye development has been well documented[5]. Congenital cystic eye is one such rare malformation, which occurs when the development is arrested at the optic vesicle stage (2 to 7 mms). Complete or partial failure of the invagination of the primary optic vesicle gives rise to a congenital cystic eye lined by neuroglial tissue with no evidence of normal ocular structures, such as lens, ciliary body, choroid, or retina[1]. It usually presents as a cystic swelling in the upper lid compared to a microphthalmos with a cyst, which usually presents as a bulge in the lower lid[2].

The MRI scan is the gold standard in diagnosing the condition along with associated lesions like encephalocele , optic nerve sheath meningocele , absence of septum pellucidum ,transsphenoidal encephalocele, hydrocephalus etc.[34]. Usually, the bony orbit does not develop in congenital cystic eye requiring conformers for expanding it[13].

However, in this case the orbit was enlarged probably due to the presence of the meningocele, pushing the cyst forwards. Identifying the presence of the meningocele before surgery is important in planning the management. Baghdassarian et al observed an optic nerve–like structure that was continuous with neuroglial tissue in the posterior aspect of a cyst[6]. During the primary excision, we also had noted transcient CSF leak from the rudimentary optic nerve head. Non ocular abnormalities like sphenoid bone malformation have been reported to be associated with congenital cystic eye[7]. Dysplasia of the greater wing of sphenoid with enlargement of the superior orbital fissure was seen in our case. However, the presence of optic nerve sheath meningocoele is a rare association.

By far, the most accepted management is to keep the cyst till the socket enlarges (usually up to 5 years of age) and excision of the congenital cystic eye followed by implantation of a prosthesis[13]. Early surgery is contemplated in large cysts with cosmetic deformity as in our case[3]. The other reported treatment modality is repeated aspiration of the cyst. This is not associated with complications like CSF leak, but may require many sittings of aspiration and may not be curative[1].

Our case demonstrates that surgical excision of the cystic eye carries a high risk of complications like CSF leak. Identifying any associated meningocele pre-operatively and repairing it during the surgery can prevent this. A trans cranial repair of the meningocele in such a case can be difficult and morbid. Alternatively, a subtotal excision, preserving the posterior part of the cyst may avoid formation of a communication with the intracranial cavity. Per operative institution of a lumbar drain which is retained till wound healing is another strategy to prevent formation of a CSF fistula. However, in the case of formation of such a fistula, periorbital tissue has to be mobilised all around the bone dura defect for closure. Ideally, this has to be done primarily while decompressing or excising the cyst.