Amyloid deposition in ocular tissues of patients with familial amyloidotic polyneuropathy (FAP)

Detection of TTR Amyloid in the Conjunctiva Using a Novel Fluorescent Ocular Tracer

Background

Transthyretin amyloidosis (ATTR) is a significant cause of cardiomyopathy and other morbidities in the elderly and Black Americans. ATTR can be treated with new disease-modifying therapies, but large shortfalls exist in its diagnosis. The objective of this study was to test whether TTR amyloid can be detected and imaged in the conjunctiva using a novel small-molecule fluorescent ocular tracer, with the implication that ATTR might be diagnosable by a simple eye examination.

Methods

Three approaches were used in this study. First, AMDX-9101 was incubated with in vitro aggregated TTR protein, and changes in its excitation and emission spectra were quantified. Second, a cadaver eye from a patient with familial amyloid polyneuropathy type II TTR mutation and a vitrectomy sample from an hATTR patient were incubated with AMDX-9101 and counterstained with Congo Red and antibodies to TTR to determine whether AMDX-9101 labels disease-related TTR amyloid deposits in human conjunctiva and eye. Last, imaging of in vitro aggregated TTR amyloid labeled with AMDX-9101 was tested in a porcine ex vivo model, using a widely available clinical ophthalmic imaging device.

Results

AMDX-9101 hyper-fluoresced in the presence of TTR amyloid in vitro, labeled TTR amyloid deposits in postmortem human conjunctiva and other ocular tissues and could be detected under the conjunctiva of a porcine eye using commercially available ophthalmic imaging equipment.

Conclusions

AMDX-9101 enabled detection of TTR amyloid in the conjunctiva, and the fluorescent binding signal can be visualized using commercially available ophthalmic imaging equipment.

Translational Relevance

AMDX-9101 detection of TTR amyloid may provide a potential new and noninvasive test for ATTR that could lead to earlier ATTR diagnosis, as well as facilitate development of new therapeutics.

Ophthalmological involvement in wild-type transthyretin amyloidosis: A multimodal imaging study

BACKGROUND AND AIMS

Ophthalmological abnormalities have been reported in hereditary transthyretin-related amyloidosis (ATTRv, v for variant) but not in wild-type transthyretin-related amyloidosis (ATTRwt).

METHODS

Patients with ATTRwt, ATTRv, and light chain amyloidosis (AL) and healthy subjects (controls) underwent complete eye examination, including optical coherence tomography (OCT), OCT angiography (OCTA), and in vivo corneal confocal microscopy (CCM).

RESULTS

Seventeen ATTRwt, nine ATTRv, two ATTRv carriers, and seven AL patients were enrolled. Compared with other groups, ATTRwt patients had 10 letters lower visual acuity and a higher prevalence of glaucoma, cataract, and retinal pigment epithelium alterations. In the whole group of patients, especially in ATTRwt, we observed (1) a reduced corneal nerve fiber length and more tortuous stromal nerves at CCM, (2) a reduced macular volume and peripapillary nerve fiber layer thickness at OCT, and (3) impairment of peripapillary and macular vascularization at OCTA.

INTERPRETATION

Ophthalmological abnormalities are common in ATTRwt, significantly impairing visual acuity. Noninvasive imaging modalities allow for the identification of small nerve fibers and small vessel damage, which may represent further warning signs for early diagnosis of ATTRwt.

Hereditary transthyretin amyloidosis: a comprehensive review with a focus on peripheral neuropathy

Amyloidoses represent a group of diseases characterized by the pathological accumulation in the extracellular area of insoluble misfolded protein material called "amyloid". The damage to the tissue organization and the direct toxicity of the amyloidogenic substrates induce progressive dysfunctions in the organs involved. They are usually multisystem diseases involving several vital organs, such as the peripheral nerves, heart, kidneys, gastrointestinal tract, liver, skin, and eyes. Transthyretin amyloidosis (ATTR) is related to abnormalities of transthyretin (TTR), a protein that acts as a transporter of thyroxine and retinol and is produced predominantly in the liver. ATTR is classified as hereditary (ATTRv) and wild type (ATTRwt). ATTRv is a severe systemic disease of adults caused by mutations in the TTR gene and transmitted in an autosomal dominant manner with incomplete penetrance. Some pathogenic variants in TTR are preferentially associated with a neurological phenotype (progressive peripheral sensorimotor polyneuropathy); others are more frequently associated with restrictive heart failure. However, many mutations express a mixed phenotype with neurological and cardiological involvement. ATTRv is now a treatable disease. A timely and definite diagnosis is essential in view of the availability of effective therapies that have revolutionized the management of affected patients. The purpose of this review is to familiarize the clinician with the disease and with the correct diagnostic pathways in order to obtain an early diagnosis and, consequently, the possibility of an adequate treatment.

Pupillometric findings in ATTRv patients and carriers: results from a single-centre experience

INTRODUCTION

Hereditary transthyretin amyloidosis (ATTRv) is a treatable multisystemic disease with great phenotypic heterogeneity. Among extra-neurological features, pupillary abnormalities have been reported, either related to amyloid deposition in the eye or to a progressive autonomic neuropathy.

OBJECTIVE

To evaluate the role of automated pupillometry, a non-invasive and rapid test able to provide objective and reproducible data on pupil size and reactivity, as a marker of disease severity in late-onset ATTRv patients.

PATIENTS AND METHODS

We performed automated pupillometry on a cohort of ATTRv patients and pre-symptomatic TTR mutation carriers and compared results to healthy controls. An exhaustive clinical and instrumental evaluation was performed on all enrolled subjects.

RESULTS

A statistically significant difference in most pupillometry parameters was found in ATTRv patients as compared to both carriers and healthy controls. Moreover, in ATTRv patients, we found a significant correlation between many pupillometry findings and disease duration, as well as widely accepted clinical scales and investigations (NIS, Sudoscan from feet, and Norfolk QoL-DN questionnaire).

CONCLUSIONS

We suggest pupillometry may play a role as a reliable and non-invasive biomarker to evaluate ATTRv disease severity and monitor its progression.

Case Report: Hereditary transthyretin (ATTRv) amyloidosis: The p.G103R mutation of the transthyretin gene in a Han Chinese family is associated with vitreous hemorrhage

Hereditary transthyretin (ATTRv) amyloidosis is a rare disease caused by transthyretin gene (TTR) mutation. We identified that the p.G103R mutation of the TTR gene in a Han Chinese family was associated with vitreous hemorrhage. The proband was a 48-year-old woman who had progressive visual impairment in both eyes for 12 years. A Glass wool–like posterior vitreous cortex attached to the posterior retinal surface of both eyes was found using ocular coherence tomography. Visual acuity improved after the first vitrectomy. Two years later, the patient underwent two more vitrectomies because of vitreous opacity recrudescence. Four years later, she presented with vitreous hemorrhage in the right eye. The vitreous fluids acquired during the vitrectomy showed increased vascular endothelial growth factor, basic fibroblast growth factor, interleukin-6, interleukin-10, vascular cell adhesion molecule, and interleukin-8. Mutation sequencing revealed a heterozygous mutation in nucleotide c.307G > C (p.G103R) in exon 3 of the TTR gene in the proband (IV-13), her daughter (IV-9), and her fourth sister (III-11). To our knowledge, this is the first case of ATTRv amyloidosis caused by a p.G103R mutation of the TTR gene associated with vitreous hemorrhage in China.

TTR Gly83Arg Mutation: Beyond Familial Vitreous Amyloidosis

BACKGROUND

Gly83Arg variation is a type of TTR mutation specific to the Chinese population. Patients of hereditary transthyretin amyloidosis (ATTR) with Gly83Arg variation predominantly present with blurred vision and most of these cases are reported by ophthalmologists. There is currently no systematic assessment of extraocular features of ATTR with Gly83Arg variation.

METHODS

Six patients and two asymptomatic carriers with molecularly confirmed Gly83Arg variation of ATTR from three unrelated families were identified by sequencing the TTR gene. The clinical, electrophysiological, ultrasonic, and pathological data were collected and analyzed.

RESULTS

This study included six patients and two carriers with TTR Gly83Arg mutation, all of whom came from the Han nationality of China. The average age of onset for the six patients was 39 years, and the course of disease ranged from 5 to 19 years. All the patients started with blurred vision, which was diagnosed as vitreous opacity (VO). Most of the patients developed sensory-motor polyneuropathies over years or even more than a decade (4-15 years) after VO. However, the heterogeneity of peripheral neuropathies among these patients remained large between families. Autonomic impairment also occurred after VO, with varying degrees of abnormalities seen in the associated autonomic assessments. None of the patients had any symptoms of cardiac impairment, but abnormal results were found in examinations. A combined biopsy of the sural nerve and muscle was also performed. Nerve pathology revealed the moderately reduced myelinated nerve fiber density and muscle pathology showed predominant neurogenic impairment accompanied by possible myogenic impairment.

CONCLUSIONS

This is a detailed account of Gly83Arg mutation-related ATTR, focusing on the extraocular presentations of this special variant in Chinese. Clinical features of this variant are early-onset, ocular involvement predominance, neurological, and cardiac involvement along with the disease, and relatively long survival.

Ocular Involvement in Hereditary Amyloidosis

The term amyloidosis describes a group of rare diseases caused by protein conformation abnormalities resulting in extracellular deposition and accumulation of insoluble fibrillar aggregates. So far, 36 amyloid precursor proteins have been identified, and each one is responsible for a specific disease entity. Transthyretin amyloidosis (ATTRv) is one of the most common forms of systemic and ocular amyloidosis, due to the deposition of transthyretin (TTR), which is a transport protein mainly synthesized in the liver but also in the retinal pigment epithelial cells. ATTRv amyloidosis may be misdiagnosed with several other conditions, resulting in a significant diagnostic delay. Gelsolin and keratoepithelin are other proteins that, when mutated, are responsible for a systemic amyloid disease with significant ocular manifestations that not infrequently appear before systemic involvement. The main signs of ocular amyloid deposition are in the cornea, irido-corneal angle and vitreous, causing complications related to vasculopathy and neuropathy at the local level. This review aims at describing the main biochemical, histopathological and clinical features of systemic amyloidosis associated with eye involvement, with particular emphasis on the inherited forms. We discuss currently available treatments, focusing on ocular involvement and specific ophthalmologic management and highlighting the importance of a prompt treatment for the potential sight-threatening complications derived from amyloid deposition in ocular tissues.

Ocular Involvement in Hereditary Transthyretin Amyloidosis: A Case Series Describing Novel Potential Biomarkers

Hereditary transthyretin amyloidosis (hATTR) is a rare disease caused by a point mutation in the transthyretin (TTR) gene and inherited in an autosomal dominant fashion. TTR is a plasma protein that functions as a carrier for thyroxine (T4) and retinol (vitamin A). Ophthalmological manifestations are due to both the hepatic and ocular production of mutated TTR. In this case series, we report the ocular manifestations of hATTR in eighteen eyes of nine consecutive patients. Corneal nerve abnormalities as well as morphological and functional changes in the retina were investigated. The study was a single-center, retrospective, observational, clinical case series. In all patients, corneal confocal microscopy (CCM), multimodal imaging of the retina, including fundus photography and Optical Coherence Tomography (OCT), as well as rod and cone electroretinography (ERG) were performed. Eight patients had active disease and one was an unaffected carrier. In all study eyes, corneal nerve plexa examined with CCM were poorly represented or absent. Mixed rod-cone and cone ERG b-wave amplitudes were reduced, and photopic b-wave responses were significantly delayed. Photopic Negative Response (PhNR) amplitude was significantly reduced, while PhNR latency was significantly augmented. In 13/18 eyes, vitreous opacities and abnormalities of vitreo-retinal interface were found. The current results highlight the presence of corneal nerve damage. Functional retinal abnormalities, detected by ERG, can be found even in the presence of minimal or absent structural retinal damage. These findings support the use of CCM and ERGs to detect early biomarkers for primary hATTR.

Pupillometry: An objective test to assess endocular hereditary transthyretin amyloidosis

OBJECTIVE

To automatically study the pupillary light reflex in patients with hereditary transthyretin-associated amyloidosis (hATTR).

METHODS

Prospective cross-sectional observational study in patients with hATTR with unilateral scalloped iris. Pupillary light reflex of scalloped iris eyes (21 eyes) were compared with non-scalloped iris eyes (21 eyes, paired eyes of the same patients) and also with a control group of 20 healthy eyes, using static and dynamic pupillometry with the Metrovision^® MonPack One.

RESULTS

No patient presented evident neurological involvment of the cranial nerves. No significant differences were found in the pupillary diameters under standardized lighting conditions (static pupillometry) among groups. In dynamic pupillometry, the amplitude of contraction, the velocity of contraction and the velocity of dilation were statistically significantly lower in eyes with scalloped iris, comparing both with the contralateral non-scalloped iris eyes (p < 0.001 for all) and with eyes from healthy subjects (p < 0.05 for all).

CONCLUSION

A scalloped iris reflects a more advanced endocular hATTR and it is associated with an altered pupillary light reflex. Pupillometry may be a quick, simple, and portable test to objectively evaluate ocular amyloid deposition in hATTR eyes. Pupillary light reflex may not be reliable to evaluate neurological dysfunction in these patients.

Excisional goniotomy with Kahook Dual Blade in a patient with glaucoma secondary to Transthyretin Amyloidosis

PURPOSE

To report for the first time the successful use of the Kahook Dual Blade excisional goniotomy technique in a patient with Transthyretin Amyloidosis.

PATIENT AND METHODS

The Kahook Dual Blade is a single use ab interno trabeculectomy device that removes the trabecular meshwork reducing aqueous humor outflow resistance. A patient with Transthyretin Amyloidosis underwent this procedure.

RESULTS

Ab interno goniotomy with Kahook Dual Blade was a successful surgical solution to reduce intraocular pressure in a patient with Transthyretin Amyloidosis secondary glaucoma controlling IOP in association with topical hypotensors for at least 6 months.

CONCLUSIONS

Ab interno goniotomy with Kahook Dual Blade is a surgical option for this type of glaucoma, that treats the main site of aqueous outflow resistance in this pathology with the advantage of being minimally invasive.

Interplay between Oxidative Stress, Inflammation, and Amyloidosis in the Anterior Segment of the Eye; Its Pathological Implications

There are different pathologies associated with amyloidogenic processes caused by the increase of reactive oxygen species (ROS) and the overactivation of inflammatory responses. These alterations are present in different regions of the anterior segment of the eye, and they have been associated with the development and progression of ocular pathologies, such as glaucoma, dry eye syndrome, keratitis, and cataracts among other pathologies. Aim. To discuss briefly the anatomical characteristics of the anterior segment of the eye and describe the interaction between oxidative stress (OS) and inflammatory responses, emphasizing the misfolding of several proteins leading to amyloidogenic processes occurring in the anterior segment and their implications in the development of ocular diseases. We performed a search on PubMed, CINAHL, and Embase using the MeSH terms “eye,” “anterior segment”, “inflammation”, “oxidative stress”, and “amyloidosis”. The search encompassed manuscripts published up to April 2019. A hundred forty-four published studies met the inclusion criteria. We present the current knowledge regarding the interaction between OS and the activation of inflammatory processes and how both can cause conformational changes in several peptides and proteins in each compartment of the anterior segment. However, we found that there is no consensus about which factor is the first to cause amyloidosis. Our conclusions suggest that there is an interplay among these factors forming a vicious cycle that leads to the loss of protein structure in ocular pathologies, and multifactorial therapies should be developed to avoid protein misfolding and to stop the progression of ocular pathologies.

Multimodal retinal imaging of familial amyloid polyneuropathy

Background: Retinal amyloid angiopathy is a sight-threatening complication of familial amyloid polyneuropathy (FAP) caused by pathological deposition of transthyretin. The purpose of this report is to present ocular findings in patients with FAP using a combination of novel non-invasive retinal imaging techniques, including first time published images of optical coherence tomography angiography (OCT-A) in FAP.Materials and methods: Observational cross-sectional study of retinal images in patients with FAP using: fundus ultra wide-field photography (UWF); autofluorescence (AF); optical coherence tomography (OCT); and, OCT-A. Fifteen eyes of eight patients with FAP from a tertiary center were included. A descriptive analysis of obtained images and clinical data was performed.Results: Amyloid vitreous and retinal deposits were easily identified using OCT scans, AF, and UWF images, especially in the red-free modality. OCT-A allowed quality reconstruction of posterior pole vasculature, foveal avascular zone, and areas of ischemia.Conclusions: Different modalities of currently available non-invasive retinal imaging techniques, including OCT-A scans described for the first time in FAP, are safe and useful in detecting and analyzing retinal amyloidosis. Retinopathy in FAP in the studied group was more frequent than previously reported.

RE-INTERVENTION IN DE NOVO VITREOUS OPACITIES AFTER PARS PLANA VITRECTOMY IN FAMILIAL AMYLOIDOTIC POLYNEUROPATHY TTR VAL30METPORTUGUESE PATIENTS

PURPOSE

To report management of de novo vitreous amyloid opacities after previous pars plana vitrectomy in familial amyloidotic polyneuropathy transthyretin Val30Met.

METHODS

This work is a retrospective observational consecutive case series of five eyes of four patients. Demographic data, transthyretin mutation involved, age at the beginning of disease, duration of disease, treatment (liver transplant or tafamidis), time between vitrectomy and re-intervention, and ophthalmologic changes were evaluated. Surgical re-intervention included phacoemulsification with intraocular lens implantation in phakic eyes, re-vitrectomy as complete as possible with posterior capsulectomy, and internal limiting membrane peeling if wrinkling of internal retinal surface was present.

RESULTS

All patients had transthyretin Val30Met mutation, and three were women. Mean age of onset of the disease was 52 ± 11.0 years, and average evolution time of the disease was 8 years. Three patients had been submitted to liver transplant 4, 9, and 15 years before. Time between first vitrectomy and surgical re-intervention was longer than 2 years in all cases. Two eyes had amyloid deposits on anterior lens surface and pupillary border with scalloped pupil. Two eyes were phakic. Glaucoma was present in two eyes; one of them had previous trabeculectomy. All cases had vitreous opacities behind posterior lens capsule and at vitreous base area. After re-intervention, no further recurrence was observed (average follow-up of 10 months).

CONCLUSION

De novo vitreous amyloid opacities may occur several years after pars plana vitrectomy. Amyloid deposition in vitreous cavity was observed only in strong vitreous adherence locations (behind posterior lens capsule and at vitreous base area). The authors expect that this procedure, an extensive re-vitrectomy associated with posterior capsulectomy, will prevent de novo vitreous amyloid opacities.

Diagnosis and management of transthyretin familial amyloid polyneuropathy in Japan: red-flag symptom clusters and treatment algorithm

Hereditary ATTR (ATTRm) amyloidosis (also called transthyretin-type familial amyloid polyneuropathy [ATTR-FAP]) is an autosomal-dominant, adult-onset, rare systemic disorder predominantly characterized by irreversible, progressive, and persistent peripheral nerve damage. TTR gene mutations (e.g. replacement of valine with methionine at position 30 [Val30Met (p.Val50Met)]) lead to destabilization and dissociation of TTR tetramers into variant TTR monomers, which form amyloid fibrils that deposit in peripheral nerves and various organs, giving rise to peripheral and autonomic neuropathy and several non-disease specific symptoms.

Phenotypic and genetic variability and non–disease-specific symptoms often delay diagnosis and lead to misdiagnosis. Red-flag symptom clusters simplify diagnosis globally. However, in Japan, types of TTR variants, age of onset, penetrance, and clinical symptoms of Val30Met are more varied than in other countries. Hence, development of a Japan-specific red-flag symptom cluster is warranted. Presence of progressive peripheral sensory-motor polyneuropathy and ≥1 red-flag sign/symptom (e.g. family history, autonomic dysfunction, cardiac involvement, carpal tunnel syndrome, gastrointestinal disturbances, unexplained weight loss, and immunotherapy resistance) suggests ATTR-FAP. Outside of Japan, pharmacotherapeutic options are first-line therapy. However, because of positive outcomes (better life expectancy and higher survival rates) with living donor transplant in Japan, liver transplantation remains first-line treatment, necessitating a Japan-specific treatment algorithm.

Herein, we present a consolidated review of the ATTR-FAP Val30Met landscape in Japan and summarize findings from a medical advisory board meeting held in Tokyo on 18th August 2016, at which a Japan-specific ATTR-FAP red-flag symptom cluster and treatment algorithm was developed. Beside liver transplantation, a TTR-stabilizing agent (e.g. tafamidis) is a treatment option. Early diagnosis and timely treatment using the Japan-specific red-flag symptom cluster and treatment algorithm might help guide clinicians regarding apt and judicious use of available treatment modalities.

Marked biochemical difference in amyloid proportion between intra- and extraocular tissues in a liver-transplanted patient with hereditary ATTR amyloidosis

In order to elucidate the pathomechanism of ocular amyloid formation in a liver-transplanted patient with hereditary ATTR amyloidosis, we investigated detailed biochemical features of ocular amyloid. The patient was a 49-year-old woman with V30M transthyretin (TTR) variant (p.TTRV50M), who underwent ophthalmectomy due to corneal rupture 10 years after liver transplantation (LT). The amyloid was selectively isolated from several portions in intra- and extraocular tissues using a laser microdissection (LMD) system and analyzed by liquid chromatography-tandem mass spectrometry to determine the composition percentage of wild-type and variant TTR in the isolated amyloid. Biochemical analysis revealed that the amyloid consisted mainly of variant TTR in intraocular tissues with a percentage > 80%. On the contrary in the extraocular muscles, wild-type TTR was the main component of the amyloid with a percentage of ∼70%. Our data indicate that intraocular amyloid formation strongly depends on locally synthesized variant TTR and the contribution of wild-type TTR to amyloid formation is quite limited.

Bilateral optic neuropathy and intraretinal deposits after pars plana vitrectomy in amyloidosis

Pathological examination of material from a nonextensive pars plana vitrectomy (PPV) in the right eye provided a diagnosis of nonfamilial amyloidosis in a 68-year-old woman, who presented with bilateral glass wool-like vitreous opacities. Genetic testing revealed a Tyr114Cys mutation in the transthyretin gene. Six months after PPV, perimetry showed intense constriction with a temporal island and central scotoma in the right eye. An extensive PPV was performed in the left eye. Spectral domain optical coherence tomography evidenced bilateral epimacular amyloid deposits and unreported reflective spots within the inner retina. One year later, visual acuity had decreased to 20/400 in the left eye, with mild vitreous opacity, pale cupped optic disc and inferior altitudinal field defect. Bilateral diurnal intraocular pressure, transiently increased after PPV, never exceeded 16 mmHg with medication. Our patient presented optic nerve blood supply impairment, due to amyloidosis, which caused optic atrophy. Epiretinal and intraretinal deposit detection could aid in diagnosing patients with suspected amyloidosis.

Ocular Manifestations and Therapeutic Options in Patients with Familial Amyloid Polyneuropathy: A Systematic Review

PURPOSE

This paper aims to review the morphological and functional characteristics of patients affected by familial amyloid polyneuropathy (FAP), with greater focus on type I and its progression after liver transplantation. We also analyse therapeutic options for the ophthalmic manifestations.

METHODS

The literature from 2002 through 2015 was reviewed, with a total of 45 articles studied, using the key terms related to amyloidosis and its therapeutic approaches. Information was collated, evaluated, critically assessed, and then summarised in its present form. PATHOPHYSIOLOGY AND TREATMENT: FAP results from mutation of the transthyretin gene, with Val30Met being the most frequent substitution. The symptoms are those typical of a sensorimotor autonomic neuropathy and can be halted with liver transplantation. Nowadays there are new medical therapies that delay the progression of the systemic neuropathy. However, there are still no options to avoid ocular disease.

CONCLUSION

The main ocular manifestations in patients with FAP type I are amyloid deposition in the vitreous, dry eye, and secondary glaucoma. Despite liver transplantation, eye synthesis of amyloid persists and is associated with progressive ocular manifestations, which require continued ophthalmologic follow-up. New therapeutic strategies are therefore needed, particularly to target the ocular synthesis of the abnormal protein.

Nonpenetrating deep sclerectomy as an effective treatment of glaucoma related to familial amyloid polyneuropathy

PURPOSE

To present the clinical course and treatment by nonpenetrating deep sclerectomy (NPDS) of open-angle glaucoma secondary to familial amyloid polyneuropathy (FAP).

PATIENTS AND METHODS

In a series of 10 patients with FAP in a tertiary ophthalmology center, 4 eyes of 3 patients required glaucoma filtration surgery and NPDS with implant, and local intraoperative mitomycin C application was performed. Intraocular pressure and anatomic bleb functionality were measured. We performed a retrospective review of data from medical charts of the 10 FAP patients, which included demographics, incidence and treatment of glaucoma, and previous vitrectomy.

RESULTS

NPDS resulted in normalization of intraocular pressure in all 4 eyes. Ten eyes (6 patients) of the studied group underwent vitrectomy because of amyloid opacities, 7 eyes (4 patients) had glaucoma, 6 of the eyes with glaucoma were previously vitrectomized, and 4 of them subsequently required glaucoma surgery.

CONCLUSIONS

NPDS is an effective treatment of FAP glaucoma. Previously vitrectomized eyes have a more severe course of glaucoma and more frequently require filtration surgery.

Secondary corneal amyloidosis after perforating corneal trauma: A series of 5 cases and review of the literature

We retrospectively reviewed the clinical and surgical histories of 5 patients with traumatic secondary corneal amyloidosis, a relatively rare sequela of nonsurgical and surgical perforating corneal trauma. Four had history of nonsurgical trauma, and 1 had surgical trauma to the cornea. Three specimens were obtained by penetrating keratoplasties and 2 by excision of the cornea during evisceration of the ocular contents. All the corneal specimens showed full-thickness scars of a prior perforating wound with congophilic amyloid deposits that exhibited apple-green birefringence under polarized light and dichroism. All cases had variable degrees of predominantly chronic nongranulomatous inflammation. Ultrastructural examination in 1 patient disclosed 8-nm diameter fibrils in disarray, consistent with amyloid. Amyloid P immunostaining was positive in all 3 patients tested for this protein.

Vitreous Amyloidosis as the Presenting Symptom of Familial Amyloid Polyneuropathy TTR Val30Met in a Portuguese Patient

Familial amyloid polyneuropathy (FAP) is a group of disorders characterized by the extracellular deposition of amyloid substance in various tissues. The peripheral nervous system and the heart are the main target organs, but the eye may also be involved. We report a case of vitreous amyloidosis as the first manifestation of FAP in a 66-year-old Portuguese man without a family history.

Recurrence of vitreous amyloidosis and need of surgical reintervention in Portuguese patients with familial amyloidosis ATTR V30M

PURPOSE

Vitreous amyloid deposits are one of the most common ocular manifestations of familial amyloidosis ATTR V30M (FAP-I), which can be the only manifestation of the disease and can appear even after liver transplantation. Removal by vitrectomy is usually performed, but vitreous amyloid recurrence has been frequently reported. This study was undertaken to evaluate the recurrence of vitreous amyloidosis and its relationship with the degree of previous vitreous removal.

METHODS

Fifty-four vitrectomized eyes from 32 patients with FAP-I were evaluated in the course of a follow-up period of 30.7 ± 17.2 months (range, 8-78; median = 30 months). An extensive, as possible, vitrectomy with indentation was performed in 41 eyes (complete), and in the others 13 eyes only a vitrectomy without indentation (incomplete) was performed. The parameters evaluated were the incidence of amyloid deposits and visual outcomes.

RESULTS

A noteworthy visual acuity gain was observed, although a few patients had a subsequent decrease of visual acuity related to new vitreous amyloid deposition in the visual axis. These new amyloid deposits did not occur in eyes that had undergone extensive vitreous removal, but only in nonextensive vitrectomized eyes (P < 0.001).

CONCLUSION

Recurrence of amyloid deposition only occurred in nonextensive vitrectomized eyes and represents a false recurrence associated with incomplete vitrectomy.

Anticipation of presbyopia in Portuguese familial amyloidosis ATTR V30M

The aim of this study was to evaluate if Portuguese patients with familial amyloidosis, liver transplanted and not, have an earlier development of presbyopia compared with a normal population and its relation with the presence or the absence of anterior capsule opacification of the lens. This study was performed to evaluate if Portuguese patients with familial amyloidosis and in a blood donors population (control group). Three hundred and fifty-six subjects, 144 amyloidotic patients and 212 healthy individuals, were evaluated for the need of plus lenses for normal near reading (Jaeger chart 1 at 33 cm). In familial amyloidosis patients, the value of the add-power was related to age, liver transplantation status, and presence of visible anterior capsule opacification of the lens. In both groups, the value of add-power was positively correlated with age (r=0.91; P<0.005). Familial amyloidosis patients require more add-power than control individuals of similar age, and need to use reading glasses at earlier ages. The age of onset of presbyopia in familial amyloidosis patients was significantly lower than in control individuals (32 years vs. 42 years). Adjusting for age, no significant difference was observed in add-power values between liver transplanted and not transplanted amyloidotic patients, suggesting that liver transplantation has no influence on presbyopia evolution in these patients. Familial amyloidosis patients had an earlier onset of presbyopia, probably related to amyloid deposition on the anterior capsule of the lens, which is not halted by liver transplantation.

Transthyretin Arg-83 mutation in vitreous amyloidosis

Both of the patients in the report had floaters and progressive vision loss for years. Two cases of familial vitreous amyloidosis occurred in three generations with typical white fibrilar opacities in the vitreous body. Pars plana vitrectomy was performed in the two patients. The vitreous specimens were subjected to histopathological examination. The specimens showed typical microscopic features of amyloidosis with Congo red stain and non-branching fibrils were seen randomly distributed with 5-10nm in diameter on a transmission electron microscope. All of the exons of the transthyretin gene were amplified with DNA isolated from the peripheral blood cells. Bi-directional sequencing of the transthyretin gene revealed a single base-pair substitution, which results in an amino acid substitution at position83, glycine to arginine (transthyretin Arg-83).

Vitrectomy for vitreous amyloidosis

AIM

To study the clinical features of vitreous amyloidosis and the effect of vitrectomy for it.

METHODS

We treated 6 eyes (4 Patients) with vitreous amyloidosis from 2008 to 2009, and followed up for 18-30 months after vitrectomy.

RESULTS

The visual acuity ranged from counting fingers to 3/50 before surgery and 15/50-40/50 after vitrectomy. No severe complication was observed.

CONCLUSION

Vitrectomy is an effective and safe treatment for eyes with vitreous amyloidosis. A long period of follow-up after surgery should be performed.

Conformational diseases: looking into the eyes

Conformational diseases, a general term comprising more than 40 disorders are caused by the accumulation of unfolded or misfolded proteins. Improper protein folding (misfolding) as well as accrual of unfolded proteins can lead to the formation of disordered (amorphous) or ordered (amyloid fibril) aggregates. The gradual accumulation of protein aggregates and the acceleration of their formation by stress explain the characteristic late or episodic onset of the diseases. The best studied in this group are neurodegenerative diseases and amyloidosis accompanied by the deposition of a specific aggregation-prone proteins or protein fragments and formation of insoluble fibrils. Amyloidogenic protein accumulation often occurs in the brain tissues, e.g. in Alzheimer's disease with the deposition of amyloid-beta and Tau, in scrapie and bovine spongiform encephalopathy with the accumulation of prion protein, in Parkinson's disease with the deposition of alpha-synuclein. Other examples of amyloid proteins are transthyretin, immunoglobulin light chain, gelsolin, etc. In addition to the brain, the accumulation of unfolded or misfolded proteins leading to pathology takes place in a wide variety of organs and tissues, including different parts of the eye. The best studied ocular conformational diseases are cataract in the lens and retinitis pigmentosa in the retina, but accumulation of misfolded proteins also occurs in other parts of the eye causing various disorders. Furthermore, ocular manifestation of systemic amyloidosis often causes the deposition of amyloidogenic proteins in different ocular tissues. Here we present the data regarding naturally unfolded and misfolded proteins in eye tissues, their structure-function relationships, and molecular mechanisms underlying their involvement in diseases. We also summarize the etiology of ocular conformational diseases and discuss approaches to their treatment.

Multi-elemental analysis of serum and amyloid fibrils in familial amyloid polyneuropathy patients

There is accumulating evidence of the involvement of biological metal imbalance in the progression of amyloid diseases such as Alzheimer's, Parkinson's and prion diseases. However, the mineral status in patients affected with familial amyloidotic polyneuropathy (FAP) has not been investigated. It is the aim of this study to determine the metal concentrations in the serum and in the transthyretin (TTR) amyloid fibrils of FAP amyloidogenic TTR (ATTR) V30M patients. Multi-elemental analysis of 17 metals by high-resolution inductively coupled plasma mass spectrometry (ICP-MS) revealed a significant decrease of the metals Fe, Cu, Zn, Cs and Ba in the serum of FAP patients (mean age 38.5 +/- 8.3 years; duration of disease 4 +/- 2.6 years) in comparison with that of healthy individuals (mean age 36.2 +/- 9.2 years). On the other hand, these metals, except Cs, were found at high levels in the amyloid fibrils of FAP patients (mean age 55.8 +/- 9.2; duration of disease 6.5 +/- 1.3 years) compared with other metals. These findings firstly suggest that the mineral status could be a candidate factor, which participates in the wide spectrum of clinical pictures of FAP patients.

Bilateral corneal perforation in familial amyloidotic polyneuropathy

PURPOSE

We report the progression of bilateral central perforating ulceration in the cornea of a patient with familial amyloidotic polyneuropathy (FAP), also known as hereditary Portuguese amyloidosis, who received two corneal grafts in an interval of 6 years. The pathology of the original host and the grafted cornea is described.

METHODS

Overall histology and immunolocalization of transthyretin, amyloid beta (Abeta), and epithelial and inflammatory markers were performed.

RESULTS

Corneal sensitivity and tear film were reduced. The grafted but not the original tissue contained amyloid deposits with transthyretin immunoreactivity. Epithelial and stromal thinning was accentuated in the graft, with epithelial dysplasia, hyperproliferation, and parakeratosis. Abundance of basement membrane material in hyperproliferative regions suggested recurrent attempts of wound healing. Activated keratocytes, ingrowth of vessels, infiltrated inflammatory, and immune cells reflect both acute and chronic inflammation.

CONCLUSION

Amyloid deposits may progressively reduce corneal sensitivity and damage epithelium and stroma. Corneal neuropathy, together with impaired tear film, may entail the pathology of dry eyes as a bystander effect, contributing to exacerbation of epithelial injury, deregulated proliferation, and parakeratosis. Once established, both acute and chronic inflammation may sustain progression of the corneal pathology.