Amyloidosis
Definition
Group of diseases characterized by abnormal protein production and tissue deposition. Nonfamilial and familial forms; familial amyloidosis (autosomal dominant [AD]) caused by substitution errors in coding of prealbumin. Can be associated with multiple myeloma.
Symptoms
Floaters, decreased vision; may have diplopia.
Signs
Although any part of the eye can be involved, vitreous involvement is most commonly seen with granular, glass-wool opacities that form in the vitreal cortex, strands attached to the retina, retinal vascular occlusions, cotton wool spots, retinal neovascularization, and compressive optic neuropathy. Other findings include eyelid hemorrhages, ptosis, proptosis, dry eye, corneal deposits, iris stromal infiltrates, and ophthalmoplegia. Systemic findings in nonfamilial forms include polyarthralgias, pulmonary infiltrates, waxy, maculopapular skin lesions, renal failure, postural hypotension, congestive heart failure, and gastrointestinal bleeds. Systemic findings in familial form include autonomic dysfunction, peripheral neuropathies, and cardiomyopathy.
Differential Diagnosis
Asteroid hyalosis (see below), vitritis, old vitreous hemorrhage.
Evaluation
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Complete ophthalmic history and eye exam with attention to tonometry, iris, lens, anterior vitreous, Hruby lens, noncontact biomicroscopic or contact lens fundus exam, and ophthalmoscopy.
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Lab tests : Complete blood count (CBC), serum protein electrophoresis, liver function tests, chest radiographs, and 12-lead electrocardiogram.
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Diagnosis made on biopsy (dichroism; birefringence with Congo red stain).
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Medical consultation.
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May require systemic treatment.
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No treatment recommended for vitreous involvement unless opacities become so severe that they affect vision, then consider pars plana vitrectomy by a retina specialist; recurs even after vitrectomy.
Prognosis
Variable depending on systemic involvement.
Asteroid Hyalosis
Multiple, yellow-white, round, birefringent particles composed of calcium phosphate soaps attached to the vitreous framework. Common degenerative process in elderly patients over 60 years of age (0.5% of population). Usually asymptomatic, does not cause floaters or interfere with vision, but does affect view of fundus; usually unilateral (75%); associated with diabetes mellitus (30%); good prognosis. Also does not affect fluorescein angiogram (FA) or optical coherence tomography (OCT) so both tests can be used to determine whether there are any retinal problems when the asteroid particles impair a direct view of the retina.
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No treatment usually recommended.
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Consider pars plana vitrectomy if particles become so severe that they affect vision or interfere with the diagnosis or treatment of retinal disorders; should be performed by a retina specialist.
Persistent Hyperplastic Primary Vitreous (Persistent Fetal Vasculature Syndrome)
Definition
Sporadic, unilateral (90%), developmental anomaly with abnormal regression of the tunica vasculosa lentis (hyaloid artery) and primary vitreous. Possibly due to abnormality of PAX6 gene.
Symptoms
Decreased vision; may have eye turn.
Signs
Leukocoria, papillary strands, strabismus, microphthalmos, nystagmus, pink-white retrolenticular/intravitreal membrane often with radiating vessels, “inverted Y” fibrovascular stalk emanating from optic nerve, Mittendorf dot; lens is clear early but becomes cataractous; associated with shallow anterior chamber (AC) (more shallow with age), elongated ciliary processes extending toward membrane, large radial blood vessels that often cover iris; may have angle-closure glaucoma (see Chapter 6 ), vitreous hemorrhage, or retinal detachment.
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