Immunocytochemical demonstration of prealbumin in the vitreous in heredofamilial amyloidosis

Vitreous amyloidosis in familial amyloidotic polyneuropathy. Report of a case with the Val30Met transthyretin mutation

We present a clinical pathological review of vitreous amyloidosis in a case of familial amyloidotic polyneuropathy, type I. Vitreous opacification was the first manifestation of disease in the proband, who was successfully treated with vitrectomy. The eyes were obtained at autopsy after the patient died from an unrelated cause, and the histopathology is presented here. Analysis of DNA from the pathology specimen revealed the most commonly reported transthyretin mutation, Val30Met. The classification of systemic and ocular amyloidosis as well as the genetics of familial amyloidotic polyneuropathy are briefly reviewed.

Ocular amyloidosis, with special reference to the hereditary forms with vitreous involvement

The complex of diseases referred to as amyloidosis is characterized by the deposition of amyloid substance in various tissues. The amyloid protein differs in the various forms of amyloidosis. This variation is the basis of the differences in affected tissues and subsequent clinical dissimilarities. Vitreous involvement in amyloidosis seems to be especially linked to some of the hereditary neuropathies associated with the amyloid protein transthyretin. Characterization of the amyloid proteins during recent decades has allowed a chemical and immunologic classification of amyloid fibrils. This paper presents the basis for classification of amyloidosis, reviews the literature on ocular amyloidosis, with special reference to vitreous involvement, and summarizes clinical findings and frequency of vitreous amyloid involvement in Swedish patients with familial amyloidotic polyneuropathy.

Changes in the soluble protein of the human vitreous in vitreoretinal disease

Samples of the vitreous were analysed in order to identify changes of soluble proteins in vitreo-retinal disease. The soluble proteins of the vitreous were separated on an anion exchange column (Mono-Q). The degree of neutral proteolytic activity in vitreous body was also measured. The vitreous from cataract cases without vitreoretinal disease was characterized by its low content of soluble proteins equivalent to about 1% of that of serum. Albumin and transferrin were the major identified components and their concentrations were approximately 0.85 and 0.03 g/l, respectively. In cases with vitreoretinal disease the vitreous showed changes of total soluble protein and the appearance of additional protein peaks. In patients with PVR the albumin concentration in the vitreous was found to be three times higher as compared to the control group consisting of patients with cataract. Neutral proteolytic activity in the vitreous was relatively low in both normal and pathological vitreous.

Prealbumin. A major constituent of vitreous amyloid

Vitreous amyloid may be the presenting clinical manifestation of types 1 and 2 familial amyloidotic polyneuropathy or complicate the course of these syndromes. Recent studies have shown that the major subunit protein composing amyloid fibrils in these conditions is a variant or abnormal prealbumin molecule and that affected individuals have low levels of this protein in their blood. The authors studied material obtained at vitrectomy from two cases of vitreous amyloid. One of these was nonfamilial and the other familial. Two-dimensional gels of solubilized protein from pelleted and washed vitreous amyloid in both cases were found to consist of material with the molecular weight and isofocusing coordinates of prealbumin monomer. Reactivity of fibrils with a monospecific antiserum to prealbumin was confirmed by colloidal gold immunoelectron microscopy. Non-familial as well as familial vitreous amyloid may in fact be systemic forms of amyloidosis due to deposition of prealbumin which can be characterized by biochemical or immunohistologic studies of material obtained at vitrectomy.

Pars plana vitrectomy for vitreous amyloidosis

Thirty-six pars plana vitrectomies were performed on 30 eyes of 17 patients with biopsy-proven vitreous amyloidosis. Reopacification of the retrolental vitreous was the most common reason for vitrectomy revision, required in 24% of patients. Complications of amyloid or vitrectomy included retinal detachment requiring scleral buckling in 17% of eyes and glaucoma requiring filtering surgery in 17% of eyes. After a mean 35-month post-vitrectomy follow-up, 48% of eyes had visual acuities of 20/40 or better, and 32% of eyes had visual acuities between 20/50 and 20/100. Twenty percent of eyes had visual acuities of 20/200 or worse due either to persistent retinal detachment, open angle glaucoma, or residual opacification of the vitreous.