A 66-year-old man with type 2 diabetes attends diabetic retinopathy screening. He has no visual symptoms and sees 6/9 in each eye. The screener notes ‘white dots throughout the vitreous’ in the right eye and refers him urgently, worried about inflammation or bleeding. The left eye is normal.
Examination Findings
Right eye: 6/9, left 6/9. Slit-lamp examination of the right vitreous shows numerous small, white, refractile spherical particles suspended throughout the vitreous — like stars in the night sky. The particles move minimally with eye movements and settle back into place. The retina can still be seen between the particles. The left vitreous is clear. There is no inflammation, no haemorrhage and no lens opacity. The patient has type 2 diabetes, well controlled.
Investigations
No investigation is required — the diagnosis is made at the slit lamp. The key clinical step is distinguishing it from synchysis scintillans: asteroid particles are white, spherical and relatively fixed; synchysis crystals are golden, flat and mobile, settling inferiorly, typically in an eye with a hypermature cataract or old trauma. B-scan is unnecessary unless the view is obscured. The diabetic retinopathy screening continues on schedule, examining between the particles.
Questions to Think About
- How do you distinguish asteroid hyalosis from synchysis scintillans at the slit lamp?
- Why does this patient not need treatment despite the dramatic appearance?
- What practical problem can asteroid hyalosis cause during diabetic screening?
Diagnosis
Asteroid hyalosis, right eye — benign incidental finding.
Reasoning
Reasoning: Numerous small white spherical refractile particles suspended in an otherwise quiet vitreous, in an asymptomatic older diabetic patient, are asteroid hyalosis — calcium-lipid complexes, usually unilateral and benign. The mimics are excluded at the slit lamp: synchysis scintillans has golden flat mobile crystals settling inferiorly with a hypermature lens; vitritis has cells and haze; haemorrhage has a red diffuse hue. Diagnosis: asteroid hyalosis, right eye. Management: typical management is reassurance alone — no drops, no laser, no surgery. The practical points are to continue diabetic screening (looking between the particles), to document the finding so future clinicians are not alarmed, and to remember that a retinal tear can still occur in such an eye, so new flashes or a shower of floaters still need urgent examination.
Differential Diagnosis
- Synchysis scintillans (cholesterolosis bulbi) — ruled out: the particles are white and fixed, not golden and mobile; the lens is clear, not hypermature.
- Vitreous haemorrhage — ruled out: no red hue, particles are discrete and refractile rather than diffuse blood.
- Vitreous inflammation (vitritis) — ruled out: no cells, no haze, quiet eye, stable chronic picture.
- Asteroid bodies of sarcoid uveitis — ruled out: no inflammation; the name is shared but the entities are unrelated.
Management
Typical management is reassurance and nothing more: the patient is told these are harmless calcium deposits in the vitreous jelly, that they do not progress to anything serious, and that no treatment exists or is needed. Diabetic retinopathy screening continues as scheduled, with the examiner looking between the particles; if the view becomes inadequate, B-scan or referral is considered. Vitrectomy is reserved for the rare case where the particles genuinely obstruct the view — almost never required.
Key Learning Points
- Asteroid hyalosis: white, spherical, fixed calcium-lipid particles — usually unilateral, benign, associated with older age and diabetes.
- Synchysis scintillans: golden, flat, mobile cholesterol crystals that settle inferiorly — associated with hypermature cataract and old ocular disease.
- The distinction is made at the slit lamp by colour, shape and mobility — no scan needed.
- Asteroid hyalosis rarely affects vision and never needs treatment; it can, however, make retinal examination and imaging harder.
Red Flags
- Vitreous particles with redness, pain or floaters shower — that is inflammation or haemorrhage, not asteroid hyalosis.
- Golden mobile crystals with a white cataract — synchysis scintillans; examine for the underlying old disease.
- New shower of floaters with flashes in an eye with asteroid hyalosis — still examine for a retinal tear; the two can coexist.
Educational content only — not medical advice. Clinical decisions must be made by a qualified professional for the individual patient.