Vitreous cysts are rare clinical entities that can occur in a normal eye or in an eye associated with other pathologies.
ICD 10- CM Code H43.89- Other disorders of vitreous body
- 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. 
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
- They have been reported to occur secondary to or associated with:
- They are usually symptomatic and associated with a reduction in visual acuity.
- Likely originate from the pigment epithelium of the iris or ciliary body and later become detached into the vitreous 
- They are brown in color
- Congenital cysts are usually non-pigmented and originate from the hyaloidal vascular system
- They are translucent, mobile and yellow-gray in color.
- 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 
These are often noted on clinical examination at the slit lamp or with funduscopy.
- 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
- Age of patients usually between 10-20 years
- Mostly unilateral, but bilateral cases have also been reported especially in retinitis pigmentosa 
- 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 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.
- 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 
- 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 
- Observation and follow-up
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