Abnormal Opacities of the Vitreous Body

 Abnormal Opacities of the Vitreous Body

Asteroid Hyalosis

These usually unilateral opacities of the vitreous body (75% of all cases) are not all that infrequent. They are thought to be linked to diabetes mellitus and hypercholesterolemia. The disorder is characterized by white calcific deposits that are associated with the collagen fibers of the vitreous body and therefore are not very mobile. Most patients are not bothered by these opaci-ties. However, the examiner’s view of the fundus can be significantly obscured by “snow flurries” of white opacities. Interestingly, these opacities do not interfere with fluorescein angiography. Vitrectomy to remove the opacities is rarely necessary and is performed only when the opacities adversely affect the patient, i.e., when visual acuity is diminished.

Synchysis Scintillans

These very rare opacities of the vitreous body usually occur unilaterally fol-lowing recurrent intraocular inflammation or bleeding. In contrast to asteroid hyalosis, these opacities are free floating cholesterol crystals in the vitreous chamber that respond to gravity. Fractile crystals are typical. Surgery is only indicated in rare cases in which the opacities impair visual acuity.

Vitreous Amyloidosis

This rare inherited autosomal dominant disorder begins at about the age of 20, progresses for decades, and finally leads to diminished visual acuity. Amy-loidosis causes characteristic amyloid deposits around the collagen fibers of the vitreous body except for the hyaloid canal, which remains unaffected. The amyloid exhibits histologically typical staining. The disorder can be treated by vitrectomy.

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