Sir,

Ever since their first description over a hundred years ago,1 vitreous cysts have remained a rare finding2 and create in most cases very few clinical symptoms. The less frequently encountered congenital cysts are mostly non-pigmented, whereas the secondary, much more frequently seen pigmented cysts are mostly due to trauma, intraocular surgery, uveitis, and other causes.3 We describe herein the dynamic growth pattern of two concentric non-pigmented vitreous cysts, which were followed clinically over a period of 6 years.

Case report

A 62-year-old male patient presented with a shadow in the visual axis of the right eye. There was no previous history of intraocular surgery or trauma. Around the same time he was diagnosed by his dermatologist with the idiopathic Morbihan syndrome, which is characterized by intermittent facial swelling.4 Ophthalmic examination showed bilateral palpebral swelling. His best-corrected visual acuity was 1.0 in both eyes and slit lamp biomicroscopy revealed a free-floating transparent vitreous cyst in the right eye. Ultrasound-B (10 Hz) examination using a horizontal scan revealed two concentric cysts, as well as a third very small cyst on the anterior wall of the smaller inner cyst (Figure 1a). Cyst diameters were 7.15 and 4.37 mm, respectively. The benign nature of the cysts was explained to the patient and no further follow-up was scheduled.

Figure 1
figure 1

(a) B-ultrasound (10 Hz) examination (Innovative Imaging Inc., Sacramento, CA, USA) at the first presentation. A small free-floating cyst is seen (diameter=4.37 mm), which is enclosed within a larger cyst (diameter=7.15 mm). Note a very small third cyst on the anterior wall of the smaller inner cyst. The retrobulbar shadow is due to the optic nerve sheath. (b) B-ultrasound (10 Hz) examination 6 years later showing the persistence of the two cysts enclosed in each other. The smaller cyst diameter has increased to 6.20 mm (volume increase by around 72 mm3) and the larger cyst diameter to 7.95 mm (volume increase by approximately 81 mm3). (c) Panoret 1000 fundus photography (Medibell, Yoqneaw Ilit, Israel) of the cyst showing small faint whitish speckles on the surface of the perfectly rounded cyst. (d) Optical coherence tomography (Zeiss, Dublin, CA, USA), using an 8-mm-wide scan showing an optically slightly distorted shape of part of the outer cyst. Note the very thin cyst wall with some areas of punctuated thickening, which may correspond to the whitish speckles seen on fundus photography.

Full size image

The patient was called back 6 years later. Visual acuity was still 1.0. Biomicroscopy and ultrasound revealed the persistence of the two previously seen concentric cysts, although the small third cyst could not be found anymore (Figure 1b–d). The volume of the larger outer cyst had increased by around 72 mm3 and that of the inner cyst by approximately 81 mm3.

In view of the stable excellent visual acuity and the absence of subjective symptoms, the patient received no further scheduled follow-up.

Comment

Congenital vitreous cysts, either of the pigmented or of the non-pigmented type, are rare and usually do not interfere with visual acuity.2 Pigmented cysts usually contain melanosomes, which resemble those from the iris or retinal pigment epithelium cells, or immature melanosomes, which suggests that these cysts may represent a choristoma of the primary hyaloidal system.3, 5, 6

Our patient showed the non-pigmented variety of the cyst, which is thought to originate from the remnants of the intraocular hyaloidal vascular system, either from the hyaloidal artery or from Bergmeister's papilla.3, 7 However, given the fact that these cysts are rarely removed surgically, the exact etiology still remains unclear.8

It is generally agreed that congenital cysts do not enlarge with time. In the present case, we could, however, record a surprisingly significant change in volume over a 6-year period. Despite this growth in size, the cysts continued to cause no substantial visual disturbances. The reason for the disappearance of the third very small cyst during the follow-up period is not clear.

It is intriguing to speculate why the vitreous cyst was discovered during the same period as when the Morbihan syndrome became symptomatic. It is, however, not known whether these two pathologies are causally linked.

The indication for possible treatment of vitreous cysts depends on the importance of the subjective clinical symptoms. Cystotomy with argon or Nd-YAG has been described,9 although the efficacy of this approach has been queried by others.3, 10 Alternatively, a pars plana vitrectomy has been proposed to ablate vitreous cysts if they give rise to severe visual impairment.3

In summary, the present case demonstrates that non-pigmented vitreous cysts can show a dynamic growth pattern and enlarge considerably in volume over several years without giving further rise to visual disturbances and the necessity of surgical removal.