Weekly Case Presentation 25-5-1401

Vitreous Cysts

Vitreous cysts are rare clinical entities that can occur in a normal eye or in an eye associated with other pathologies.

Disease Entity

ICD 10- CM Code H43.89- Other disorders of vitreous body

Disease

• Floating vitreous cysts are extremely rare clinical entities that are regarded as ‘ocular curiosities’.
• They can either be an incidental finding in a normal eye or associated with other ocular pathologies.
• It was first described by Tansley in 1899 as an irregular spherical cyst that showed lines of pigment on its surface.

A red-free fundus photo showing a vitreous cyst anterior to the optic disc
Photo Courtesy- Rajan Eye Care Hospital, Chennai

Etiology

Vitreous cysts can be congenital or acquired.

Congenital Cysts

• Remnants of the hyaloid vascular system
• Located at hyaloid canal and found in conjunction with a Mittendorf’s dot or Bergmeister’s papillae
• They are usually stable, do not progress and rarely interfere with visual acuity
• They are usually non-pigmented pearl-gray cysts with a smooth surface, can be sessile or pedunculated
• They are located anterior to the optic disc
• Some can be limited in movement due to vitreous strands attaching the cyst to the optic disc

Acquired Cysts

• They have been reported to occur secondary to or associated with:
  • Ocular trauma
  • Intraocular inflammation/infection/ uveitis eg. Intermediate Uveitis, Toxoplasmosis
  • Retinal diseases such as Retinitis pigmentosa, Choroidal atrophy, Retinoschisis, High myopia with uveal coloboma etc.
  • Retinal detachment surgeries
• They are usually symptomatic and associated with a reduction in visual acuity.

Types

Pigmented Cysts

• Likely originate from the pigment epithelium of the iris or ciliary body and later become detached into the vitreous
• They are brown in color

Non-Pigmented Cysts

• Congenital cysts are usually non-pigmented and originate from the hyaloidal vascular system
• They are translucent, mobile and yellow-gray in color.

General Pathology

Histopathological examination:

• Congenital cysts are choristomas (normal tissues growing in abnormal location) of the primary hyaloidal system
• Derived from the pigment epithelium of the iris or ciliary body
• Contains immature melanosomes

Light & Electron Microscopy:

• Orellana et al studied aspirated pigmented cyst by light microscopy and electron microscopy.
• They found that the pigmented layer of cuboidal cells contains large mature melanosomes and few immature melanosomes suggesting origin from the pigment epithelium.

Pathophysiology of Acquired Cysts

• Trauma can cause damage to the pigment epithelium of ciliary body and create pigment cysts
• Other theories: Vitreous reaction to underlying retinal degeneration can causes cysts, Ciliary adenoma breaking into the vitreous, cystic growths that occur at site of coloboma that enter the vitreous

Diagnosis

These are often noted on clinical examination at the slit lamp or with funduscopy.

History

• History of ocular trauma
• History of infections or inflammations of the eye
• History of ocular surgery
• History of ocular disease such as:  uveitis, uveal coloboma, retinoschisis, retinitis pigmentosa, retinal detachment and ocular malignancies

Clinical Presentation

• Age of patients usually between 10-20 years
• Mostly unilateral, but bilateral cases have also been reported especially in retinitis pigmentosa

Symptoms

• Usually asymptomatic
• When a cyst floats into and obstructs the visual axis, patients can complain of transient blurring of vision, floaters, shifting visual field defects and occasionally photophobia.

Signs and Morphological appearance of the cysts

• Numbers and Positioning: Single unilateral, Single Bilateral, Multiple unilateral
• Dimensions: 0.15-12 mm
• Shapes: Spherical, Oval, Lobulated
• Surface: Smooth or Crenated
• Color: Yellow-gray (non-pigmented) or Brown (Pigmented)
• Location:  Confined to the region of Cloquet’s canal

The cysts can move with a patient’s eye movements while examining with an indirect ophthalmoscope.A colour fundus photo showing a well-defined round parasitic cyst of cysticercosis in the vitreous cavity
Photo Courtesy- Rajan Eye Care Hospital, Chennai

Differential diagnosis

• A detailed clinical examination is required to rule out other infectious and malignant conditions.
• Pigmented cysts can mimic pigmented ocular tumors such as malignant melanoma.
• Nonpigmented cysts can mimic parasitic cysts such as Cysticercosis, Echinococcus etc.

Investigations

General Investigations:

• Complete blood count
• Erythrocyte Sedimentation Rate
• Serologies for Cysticercosis, Echinoccous, Toxpoplasma gondii, Toxocara canis
• Stool examination for ova and cysts
• Chest radiography
• Abdominal Ultrasound
• Brain computer tomography

Ocular Investigations:B scan Ultrasonography showing a vitreous cyst with a hyperechogenic wall and acoustically hollow interior with no connections to any part of the eye ie free floating. No scolex seen. Suggestive of a primary floating vitreous cyst. Photo Courtesy- Rajan Eye Care Hospital, Chennai

• B Scan Ultrasound to look for scolex in case of cysticercosis
• Optical coherence tomography (OCT) can also help characterize the cyst
• Ultrasound biomicroscopy (UBM) to rule out anomalies of ciliary body or posterior iris
• Fluorescein angiography – assists in characterization of intra and extra cystic vascularization

Management

Asymptomatic cysts

• Observation and follow-up

Symptomatic cysts

• Laser cystotomy by Argon laser or Nd:Yag laser
• Pars plana vitrectomy with cyst excision