Asteroid hyalosis

Asteroid hyalosis is a degenerative condition of the eye involving small white opacities in the vitreous humor

Asteroid hyalosis has the striking clinical appearance of glistening, yellowish white, spherical bodies suspended throughout the vitreous.

Although the asteroid bodies can be so dense as to obscure the fundus, the patient is usually completely asymptomatic, with no decrease in visual acuity.

▪️Asteroid hyalosis is unilateral in over 75% of cases. It is common seen in 1 of 200 person

asteroid hyalosis
Asteroid Hyalosis (Behind The IOL),Photo credit: eye_ratlas.

On examination, the asteroids appear as multiple, yellow-white, round, birefringent crystals floating in the vitreous space.

▪️Asteroid hyalosis is a common degenerative process seen in elderly patients over 60 years of age (0.5% of the population) and in patients with diabetes mellitus (30% of diabetics). Most cases are unilateral (75%).

▪️Surprisingly, it is usually asymptomatic, and does not cause floaters or interfere with vision. However, the particles can interfere with the examiner’s view of the retina.

▪️The prognosis is good and in general no treatment is recommended. In rare circumstances, a pars plana vitrectomy is performed if the asteroids become so severe that they affect vision or interfere with the diagnosis or treatment of retinal disorders.(ref 1)

Asteroid hyalosis causes

Doctors are not sure what causes asteroid hyalosis, but they know the risk increases as you age. It typically affects patients aged 55 and older, and men are twice as likely as women to develop the condition.

Some studies suggest a link between asteroid hyalosis and other health issues, such as:

  • Diabetes
  • Excess alcohol consumption
  • Heart disease
  • High blood pressure
  • Higher body mass index
  • High cholesterol
  • History of gout

However, other studies have found no significant link between asteroid hyalosis and any of these risk factors. More research is needed on the cause of asteroid hyalosis.

Asteroid hyalosis Vs synchysis scintillans

Benson, in 1894, was the first to describe accurately and to differentiate AH from synchysis scintillans. Because the vitreous particles resembled “stars on a clear night” he termed the condition asteroid hyalitis, but Luxenberg and Sime later suggested the term “asteroid hyalosis” in view of the absence of inflammatory changes

Asteroid hyalosis (AH) is a degenerative eye condition marked by  a buildup of calcium and lipids, or fats, in the fluid between your  eye’s retina and lens, called the vitreous humor. It’s commonly  confused with synchysis scintillans, which looks very similar.

However, synchysis scintillans refers to a buildup of cholesterol  instead of calcium.

Asteroid hyalosis (AH) Vs synchysis scintillans
Asteroid hyalosis (AH) Vs synchysis scintillans

Asteroid Hyalosis vs Synchisis Scintillans:

▶️ Definition:
▪️Asteroid hyalosis: White refractile crystals composed of calcium soaps that float in the vitreous and do not settle with gravity.
▪️Synchisis Scintillans: Brown refractile crystals composed of cholesterol that float in the vitreous and do settle with gravity.

▶️ Symptoms of patient:
•Patients are usually asymptomatic

▶️Signs :
•Small, white refractile particles made up of calcium soap;float in the vitreous ;do not settle with gravity.
•Monocular in 75% of cases
•Asteroid hyalosis occurs more often in diabetic patients.
▪️Synchisis Scintillans: Numerous yellow-white or gold particles made up of cholesterol; located in the vitreous and anterior chamber; settle to the bottom of the eye with gravity.

▶️ Investigations :
▪️Asteroid hyalosis: Fluorescein angiogram can be performed to view the macula clearly if patients present with decreased vision and if the view of the posterior pole is obscured by the asteroid.
▪️Synchisis Scintillans: Careful history to determine if there was previous surgery or trauma to the eye.

▶️ Differential Diagnosis of Asteroid hyalosis:
•Past vitreous hemorrhage
•Pigment floating in the vitreous.

▶️ What causes asteroid hyalosis?
▪️Asteroid hyalosis:
•An innocuous degenerative disease of unknown origin
•Usually diagnosed in patients more than 60years of age.
▪️Synchisis Scintillians
History of severe, accidental,or surgical trauma associated with a large intraocular hemorrhage.

▶️Associated Features:
Synchisis Scintillans: Posterior vitreous detachment; this often allows the crystals to settle inferiorly.

▶️ Pathology:
▪️Asteroid hyalosis: Calcium and lipid particles ranging from 0.01–0.10 mm in diameter.
▪️Synchisis Scintillans: Cholesterol particles.

▶️ Pearls and Considerations:
•Asteroid hyalosis has no clinical association, where as synchisis scintillans is often found after vitreous hemorrhage, uveitis or trauma.(ref 2)

Ref 1:Essentials of Ophthalmology-Friedman.
ref 2: Ophthalmic Diagnosis & Treatment 3rd edition

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