Other Names
Cholesterolosis bulbi: Also called ocular cholesterosis. It refers to a condition in which the vitreous is filled with cholesterol crystals.
Asteroid Hyalosis
Key Points at a Glance
Section titled “Key Points at a Glance”1. What is Synchysis Scintillans?
Section titled “1. What is Synchysis Scintillans?”Synchysis scintillans is a degenerative eye disease in which cholesterol crystals accumulate within the degenerated vitreous. It was first described by Parfait-Landrau in 1828 1). It is also called “cholesterolosis bulbi.”
The prevalence is approximately 0.003%, which is extremely rare 1), and the most common age of onset is in the 30s. Clear data on gender differences are limited. Most cases are unilateral and have a preceding ocular disease.
Typical Age of Onset
30s: Most common age of onset. The age range is wide because it develops against a background of preceding ocular diseases (such as trauma or vitreous hemorrhage).
Nature of the Crystals
Cholesterol crystals: Precipitated from degenerated blood components. They are plate-like and exhibit a golden to white luster.
Trigger for Discovery
Preceding ocular diseases: Such as trauma, vitreous hemorrhage, or retinal detachment. Crystals form due to degeneration of blood components.
Q
What is the difference between synchysis scintillans and asteroid hyalosis?
A
In synchysis scintillans, cholesterol crystals precipitate due to gravity, whereas in asteroid hyalosis, calcium-soap complexes remain attached to vitreous fibers and do not move. For details, see the “Diagnosis and Testing Methods” section.
2. Main Symptoms and Clinical Findings
Section titled “2. Main Symptoms and Clinical Findings”Subjective Symptoms
Section titled “Subjective Symptoms”The majority of synchysis scintillans cases are asymptomatic. Visual impairment due to the crystals themselves is usually not present. When the following symptoms occur, they are often due to complications or the underlying disease.
- Floaters: The movement of crystals may be perceived as shadows in the visual field.
- Decreased vision: Often due to underlying diseases (e.g., diabetic retinopathy, Coats disease).
Clinical Findings
Section titled “Clinical Findings”Slit-lamp microscopy and fundus examination reveal the following characteristic findings.
- Golden to white floating crystals: They swirl within the vitreous with eye movement and settle downward due to gravity when at rest (snow globe phenomenon). Plate-like cholesterol crystals reflect light, giving a golden or copper-colored sheen.
- Pseudohypopyon in the anterior chamber: When crystals spread from the vitreous to the anterior chamber, they appear as a white to yellow layered deposit in the lower anterior chamber. Differentiation from inflammatory hypopyon is necessary1)2).
- Vitreous liquefaction: The degenerated vitreous is liquefied, providing an environment where crystals can move freely.
Q
What is pseudohypopyon in the anterior chamber? Why does it occur?
A
This refers to a condition where crystals migrate from the posterior segment to the anterior chamber and settle in the lower anterior chamber. It resembles inflammatory hypopyon (pus accumulation) in appearance but differs in that it is not accompanied by inflammatory findings1). Anatomical continuity within the eye and gravity are involved.
3. Causes and Risk Factors
Section titled “3. Causes and Risk Factors”Synchysis scintillans occurs when blood components in the vitreous body undergo chronic degeneration and precipitation. Primary (idiopathic) cases are rare, and most are secondary to the following preceding conditions 1).
- Ocular trauma: The most common cause of blood component influx into the vitreous.
- Vitreous hemorrhage: Hemorrhage secondary to diabetic retinopathy, retinal vein occlusion, etc., becomes chronic and leads to crystal precipitation.
- Retinal detachment: Degenerative changes associated with long-standing retinal detachment predispose to this condition.
- Coats disease: Among exudative retinopathies, accumulation of blood and lipid components in the vitreous promotes crystal formation.
- Diabetic retinopathy (DM retinopathy): Vitreous hemorrhage associated with proliferative changes becomes chronic, leading to the condition.
In 2025, Aleshawi et al. reported the first case of cholesterolosis bulbi secondary to retinal capillary hemangioma 2). This means that hemangioma has been newly added as a cause of this disease.
4. Diagnosis and Examination Methods
Section titled “4. Diagnosis and Examination Methods”Clinical Diagnosis
Section titled “Clinical Diagnosis”Diagnosis is primarily a clinical diagnosis using slit-lamp microscopy and fundus examination. The snow globe phenomenon (crystal dispersion after eye movement and gravitational sedimentation at rest) is characteristic of this disease and can often be confirmed by an experienced ophthalmologist.
Examination with a polarizing filter can confirm the cholesterol nature of the crystals. If histological confirmation is needed, oil red O staining can be used to stain cholesterol crystals 1).
In the case reported by Aleshawi et al., the cholesterol content was quantitatively confirmed by chemical analysis of the vitreous humor2). This is useful as a definitive diagnostic tool in special situations (such as during surgery).
Differential Diagnosis
Section titled “Differential Diagnosis”The most important differential diagnosis is distinction from asteroid hyalosis.
| Feature | Synchysis Scintillans | Asteroid Hyalosis |
|---|---|---|
| Crystalline component | Cholesterol | Calcium-soap complex |
| Behavior at rest | Settles by gravity | Adherent to vitreous fibers |
| Background vitreous | Liquefied (degenerated) | Preserves normal structure |
When presenting with pseudohypopyon in the anterior chamber, differentiation from bacterial/fungal endophthalmitis, hyphema, and uveitis (pus associated with uveitis) is necessary, and the presence or absence of inflammatory findings is key to differentiation 1).
Q
Why is it important to distinguish from asteroid hyalosis?
A
Asteroid hyalosis usually occurs in healthy eyes, requires no treatment, and has a good prognosis. In contrast, synchysis scintillans is associated with pre-existing ocular diseases and requires management of the underlying condition, so differentiating between the two directly determines the treatment strategy.
5. Standard Treatment
Section titled “5. Standard Treatment”Principle: Observation
Section titled “Principle: Observation”Synchysis scintillans itself is often asymptomatic, and in principle, active treatment is not necessary. Regular follow-up and management of the underlying disease are fundamental.
Treatment for Cases with Complications
Section titled “Treatment for Cases with Complications”Below are treatments for cases with complications reported in the literature.
Case 1: Complicated with NVG
Overview: A case of synchysis scintillans complicated by anterior chamber cholesterol crystal deposition and neovascular glaucoma (NVG) 1).
Treatment: Intracameral injection of bevacizumab (anti-VEGF agent) was performed. The cholesterol crystals in the anterior chamber disappeared, and intraocular pressure control was achieved.
Significance: A rare report that anti-VEGF therapy contributed to the resolution of anterior chamber crystals.
Case 2: Complicated with Hemangioma
Overview: A case of cholesterolosis bulbi (first report) with underlying retinal capillary hemangioma 2).
Treatment: Removal of cholesterol crystals by anterior chamber irrigation and laser photocoagulation for retinal hemangioma were performed.
Significance: A combined approach that integrates treatment of the underlying disease with local procedures.
Q
Is it necessary to remove crystals surgically?
A
Visual impairment due to crystals alone is usually mild, and surgery (vitrectomy) is generally not recommended. However, it may be considered when necessary for the treatment of complications (e.g., glaucoma, retinal diseases).
6. Pathophysiology and Detailed Mechanisms
Section titled “6. Pathophysiology and Detailed Mechanisms”Mechanism of Cholesterol Crystal Formation
Section titled “Mechanism of Cholesterol Crystal Formation”In asteroid hyalosis, cholesterol crystals are formed by chronic degeneration of blood components that have entered the vitreous 1). The following pathways are thought to be involved.
| Pathway | Description | Associated Diseases |
|---|---|---|
| Blood degeneration | Cholesterol from red blood cell membranes dissolves and precipitates | Trauma, vitreous hemorrhage |
| Precipitation of exudative components | Accumulation of cholesterol derived from plasma lipoproteins | Coats disease, diabetic retinopathy |
| Vascular wall degeneration | Exudation from abnormal vessels and accumulation of degenerative products | Retinal capillary hemangioma |
Liquefied vitreous does not impede crystal movement, leading to gravity-dependent sedimentation (snow globe phenomenon). This phenomenon is less likely when the normal vitreous gel structure is preserved.
Physical properties of cholesterol crystals
Section titled “Physical properties of cholesterol crystals”Cholesterol crystals have a plate-like (flat) and pointed shape, and exhibit a golden or copper-colored sheen due to their reflective properties. This shape is fundamentally different from the spherical crystals of asteroid hyalosis (calcium-soap complex). Because the plate-like crystals reflect light at specific angles, a multicolored shimmer is observed under ophthalmoscopy.
Vitreous liquefaction is a prerequisite for this condition; in liquefied vitreous, cholesterol crystals can float and sediment freely. In contrast, in asteroid hyalosis, the vitreous does not liquefy, and cholesterol crystals are fixed in place.
B-mode ultrasound findings
Section titled “B-mode ultrasound findings”On B-mode ultrasound, a dynamic pattern is observed: after eye movement, hyperechoic particles disperse within the vitreous cavity, and at rest, they accumulate in the direction of gravity (inferior part of the globe). This “gravity sedimentation pattern” helps differentiate from asteroid hyalosis (where particles are uniformly distributed throughout the vitreous). When complicated by retinal detachment or vitreous hemorrhage, ultrasound is essential for detailed evaluation of the posterior segment.
Oxidative stress hypothesis
Section titled “Oxidative stress hypothesis”Chronic presence of blood components may increase oxidative stress within the vitreous and promote lipid peroxidation. Oxidatively modified cholesterol esters become water-insoluble and tend to precipitate as crystals.
Support from chemical analysis
Section titled “Support from chemical analysis”In the report by Aleshawi et al. (2025), chemical analysis of vitreous humor collected during surgery quantified cholesterol content, confirming that exudative components derived from the hemangioma are the direct cause of crystal formation 2). This is one of the first reports to chemically support the pathophysiology of this disease.
7. Latest Research and Future Perspectives (Investigational Reports)
Section titled “7. Latest Research and Future Perspectives (Investigational Reports)”First Report of a Case with Hemangioma
Section titled “First Report of a Case with Hemangioma”Aleshawi et al. (2025) reported the world’s first case of cholesterolosis bulbi secondary to retinal capillary hemangioma 2). Chemical analysis quantified cholesterol in the vitreous humor, confirming that exudative components from the hemangioma cause crystal formation. Combined anterior chamber irrigation and laser photocoagulation yielded good results.
This report expands the list of causes of synchysis scintillans, and in patients with hemangioma, the possibility of this condition should be considered.
Case with NVG and Anti-VEGF Therapy
Section titled “Case with NVG and Anti-VEGF Therapy”Bayraktar et al. (2024) reported a case of synchysis scintillans with anterior chamber cholesterol crystal deposition and neovascular glaucoma (NVG) 1). The resolution of anterior chamber crystals after intravitreal injection of bevacizumab suggests that anti-VEGF therapy may promote crystal reabsorption by suppressing inflammation and exudation from new vessels.
Further case accumulation and elucidation of mechanisms are needed regarding the causal relationship between anti-VEGF therapy and the resolution of anterior chamber cholesterol.
Q
Are new treatments being developed?
A
Currently, only case report-level findings are available, and there is no high-level evidence such as randomized controlled trials. Although anti-VEGF therapy and chemical analysis are advancing the understanding of the pathophysiology 1)2), further research is needed to establish standard treatment.
8. References
Section titled “8. References”- Bayraktar S, et al. Anterior chamber synchysis scintillans with neovascular glaucoma: a case report and review of the literature. J Ophthalmic Vis Res. 2024.
- Aleshawi A, et al. Cholesterolosis bulbi secondary to retinal capillary hemangioma: first reported case with chemical analysis. Am J Ophthalmol Case Rep. 2025.
- Hasnaoui I, Hassina S, Krichen MA, Elhassan A, Berraho A. Synchysis scintillans: Nature’s snow globe. J Fr Ophtalmol. 2023;46(9):1117-1119. PMID: 37414669.