Bilateral vitreous opacification can occur as an early manifestation of the dominantly inherited form of familial amyloidosis, which is most commonly associated with a transthyretin mutation (Fig 17-13). Amyloid infiltration of the vitreous is rare in nonfamilial cases. In addition to the vitreous, amyloid can be deposited in the retinal vasculature, the choroid, and the trabecular meshwork.
Retinal findings include hemorrhages, exudates, cotton-wool spots, and peripheral retinal neovascularization. In addition, infiltrations may be present in the orbit, extraocular muscles, eyelids, conjunctiva, cornea, and iris. Nonocular manifestations of amyloidosis include upper- and lower-extremity polyneuropathy and central nervous system abnormalities. Amyloid can be deposited in several organs, including the heart and skin, and in the gastrointestinal tract.
Initially, the extracellular vitreous opacities appear to lie adjacent to retinal vessels posteriorly; they later develop anteriorly. At first, the opacities appear granular and have wispy fringes, but as they enlarge and aggregate, the vitreous takes on a “glass-wool” appearance. With vitreous liquefaction or PVD, the opacities may be displaced into the visual axis, causing reduced vision and photophobia.
The differential diagnosis of amyloidosis includes chronic (dehemoglobinized) vitreous hemorrhage, lymphoma, sarcoidosis, and Whipple disease. Vitrectomy may be indicated for vitreous opacities when symptoms warrant intervention, but recurrent opacities may develop in residual vitreous. Histologic examination of removed vitreous shows material with a fibrillar appearance and a staining reaction characteristic of amyloid. Birefringence and electron microscopic studies are confirmatory. Immunocytochemical studies have shown the major amyloid constituent to be a protein resembling prealbumin.
Figure 17-13 Amyloidosis. Images from a 57-year-old woman with a history of vitrectomy for floaters in the right eye. A cataract subsequently developed in the right eye and was extracted. Her vision then decreased in the left eye, which she ascribed to a cataract. A, Color fundus photograph of the left eye showed a dense vitreous infiltration; there was no cataract, and intraocular pressure was markedly elevated. Review of systems revealed carpal tunnel syndrome in both wrists. B, After vitrectomy surgery on the left eye, the color fundus photograph revealed retinal hemorrhages along the inferotemporal vascular arcade. C, The removed vitreous material, stained with Congo red, demonstrated birefringence (D). The patient was found to have a mutation affecting transthyretin. Glaucoma commonly develops in patients with transthyretin-related familial amyloidotic polyneuropathy.
(Courtesy of Richard F. Spaide, MD.)
Excerpted from BCSC 2020-2021 series: Section 10 - Glaucoma. For more information and to purchase the entire series, please visit https://www.aao.org/bcsc.