Orbital solitary fibrous tumor: radiographic and histopathologic correlations.

OBJECTIVE: To correlate the clinicopathologic and radiographic features characteristic of orbital solitary fibrous tumor (SFT). METHODS: The diagnostic features and clinical outcome of seven adults with orbital SFT are retrospectively outlined. Orbital imaging was performed by ultrasonography, computed tomography, or magnetic resonance imaging. Some cases were imaged by multiple modalities. Histopathologic examination of each tumor specimen included standard light and immunohistochemical stains. RESULTS: Heterogeneous internal composition was better appreciated on magnetic resonance imaging than on computed tomography. All cases undergoing magnetic resonance imaging showed T1 isointensity and T2 hypointensity relative to gray matter. Strong, generalized immunohistochemical reactivity to vimentin and CD34 validated the diagnosis of SFT and differentiated the specimens from other spindle cell neoplasms. After complete tumor resection, our patients remain tumor free with postoperative intervals of 15 to 45 months. CONCLUSIONS: Solitary fibrous tumor has now been reported in 26 orbits. No physical finding is pathognomonic, but several imaging traits are highly characteristic. Intralesional image heterogeneity and a predominantly low T2 signal intensity are distinctive of SFT. Complete tumor resection and immunohistologic specimen evaluation are emphasized. Clinicians should consider the diagnosis of SFT when confronted with an adult patient having an orbital soft tissue mass demonstrating the distinctive magnetic resonance imaging findings.

Fine-needle aspiration for the diagnosis of primary epithelial tumors of the lacrimal gland and ocular adnexa.

Results of fine-needle aspiration (FNA) of solid-tissue neoplasms arising in the periocular glands are infrequently reported in the literature. To our knowledge, no previous series relating to this topic exist. Neoplastic processes that arise in the semiconfined area of the orbit behave as space-occupying lesions. Such lesions can exert significant pressure on the globe, be responsible for altered vision, and result in proptosis. When noninvasive techniques fail to confirm or rule out the suspicion of a neoplastic lacrimal or adnexal lesion, FNA may be of use in establishing a diagnosis in an efficient, reliable, timely, cost-effective, and safe manner. During the 14-yr interval from 1986-1999, 77 orbital/ocular needle aspiration biopsies were conducted by staff ophthalmologists at Allegheny General Hospital (Pittsburgh, PA). Review of the diagnoses for these specimens revealed seven primary solid-tissue lesions of the lacrimal gland and other adnexal glands, all arising in adult patients (age range, 45-92 yr; mean age, 74 yr). Primary lacrimal and adnexal gland neoplasms were found to represent approximately 9% of orbital fine-needle aspirations (7/79). The 7 cases included 3 lacrimal gland lesions diagnosed as benign mixed tumors, 3 lesions diagnosed as adenoid cystic carcinoma of the lacrimal gland, and 1 tumor diagnosed as sebaceous carcinoma of the meibomian holocrine glands. Cytologic diagnoses were rendered using standard criteria for salivary gland-type tumors. Tissue confirmation was available from surgical follow-up in 4 of the 7 cases, with 100% correlation. Although primary neoplasms of the lacrimal gland and glands of the eyelids are rare, accurate diagnoses of such lesions may be established with minimally invasive aspiration techniques. Preoperative aspiration biopsy diagnoses provide a great advantage to ophthalmic surgeons who routinely operate in a conservative fashion in an area of the body requiring great attention to cosmesis. Our experience indicates that FNA is a reliable and effective tool in the diagnosis and management of primary lacrimal and ocular adnexal tumors.

Surgery for orbital tumors. Part II: transorbital approaches.

Orbital tumors can be excised or biopsy samples obtained via transorbital approaches, especially those located in the anterior two thirds of the orbit. The indications and various surgical steps will be reviewed for the anterior, the anteromedial, and the lateral approaches. Some of these approaches can be combined or extended to accommodate large or deep-seated tumors.

Fine-needle aspiration for the diagnosis of orbital hematolymphoid lesions.

Ocular and periocular hematolymphoid diseases are a diverse group of lesions affecting various soft tissue structures within the orbital cavity. Lymphoid proliferations in particular are among the most commonly diagnosed entities in orbital pathology. When noninvasive techniques fail to confirm or rule out the suspicion of orbital neoplasia, fine-needle aspiration (FNA) may be of use in establishing a diagnosis in a reliable, timely, cost-effective and safe manner. From 1986 to 1999, 79 orbital/ocular needle aspiration biopsies were conducted by staff ophthalmologists at Allegheny General Hospital. Slides from these cases and corresponding reports were pulled from the cytology files and grouped into the two broad categories of hematolymphoid and other. Specimens came from patients ranging in age from 14 to 88 years (mean, 64 years) with eight patients having known histories of hematolymphoid disorders. Immunocytochemical (ICC) studies were performed in 33% of the cases (14/43). Review of the diagnoses for the 79 aspiration specimens revealed 30 cases diagnosed as lymphoma/atypical lymphocytic infiltrate, cases diagnosed as inflammation or abscess, three cases diagnosed as plasmacytoma, three cases called suboptimal with scant inflammatory cells, and one case of Langerhans' cell histiocytosis. Hematolymphoid diagnoses accounted for 54% (43/79) of all diagnoses. Histologic correlation was available in 33% (14/43) of the cases (nine cases diagnosed as cytologically atypical/malignant and five cases called cytologically benign/suboptimal) with 100% correlation. Hematolymphoid lesions of the orbit are readily diagnosed by FNA. Because many hematolymphoid malignancies are treated as systemic or multiorgan system diseases and because ocular lymphomas may also involve the central nervous system, nonsurgical attempts at diagnosis have the potential to spare the patient procedural morbidity which may be associated with open biopsy. Our experience indicates that the combination of FNA, judicious use of immunocytochemical studies, and correlation with pertinent clinical information and imaging studies allows for reliable and effective classification and diagnosis of orbital hematolymphoid lesions.

Heritable gene silencing in Drosophila using double-stranded RNA.

RNA-mediated interference (RNAi) is a recently discovered method to determine gene function in a number of organisms, including plants, nematodes, Drosophila, zebrafish, and mice. Injection of double-stranded RNA (dsRNA) corresponding to a single gene into organisms silences expression of the specific gene. Rapid degradation of mRNA in affected cells blocks gene expression. Despite the promise of RNAi as a tool for functional genomics, injection of dsRNA interferes with gene expression transiently and is not stably inherited. Consequently, use of RNAi to study gene function in the late stages of development has been limited. It is particularly problematic for development of disease models that reply on post-natal individuals. To circumvent this problem in Drosophila, we have developed a method to express dsRNA as an extended hairpin-loop RNA. This method has recently been successful in generating RNAi in the nematode Caenorhabditis elegans. The hairpin RNA is expressed from a transgene exhibiting dyad symmetry in a controlled temporal and spatial pattern. We report that the stably inherited transgene confers specific interference of gene expression in embryos, and tissues that give rise to adult structures such as the wings, legs, eyes, and brain. Thus, RNAi can be adapted to study late-acting gene function in Drosophila. The success of this approach in Drosophila and C. elegans suggests that a similar approach may prove useful to study gene function in higher organisms for which transgenic technology is available.

The clinical spectrum of schwannomas presenting with visual dysfunction: a clinicopathologic study of three cases.

Schwannomas (neurilemomas) are benign tumors that arise from Schwann cells in the peripheral nervous system. The most commonly involved nerves that cause neuro-ophthalmic manifestations are cranial nerves V and VIII. In this series of three women, schwannomas presented as intraconal masses that mimicked a cavernous hemangioma, a superior orbital mass transgressing the superior orbital fissure, and an expansive frontal lobe mass with clinical symptoms and signs of increased intracranial pressure. Although all three complained of visual blurring, none of our patients presented with Vth or VIIIth cranial nerve dysfunction. Histopathologic studies demonstrated well-circumscribed, encapsulated spindle-cell lesions with classic Antoni A and B patterns. Histopathologic examination is essential to confirm the diagnosis of a schwannoma that may be otherwise clinically confusing. Direct optic nerve compression, globe indentation with induced hyperopia, or increased intracranial pressure with optic nerve compromise may be responsible for visual symptoms. A multidisciplinary approach is often required because of the size and location of schwannomas.

Significance of serum antibodies reactive with flavoprotein subunit of succinate dehydrogenase in thyroid associated orbitopathy.

AIMS: Thyroid associated orbitopathy (TAO) is an autoimmune disorder of extraocular muscles and orbital connective tissue. Identification of the principal target antigens would help the understanding of the pathogenesis of the disease and possibly lead to the development of specific therapies in the future. The purpose of this study was to measure serum antibodies against the flavoprotein subunit of succinate dehydrogenase in patients with TAO and correlate their presence with factors of TAO. METHODS: Sera of patients with active TAO of 6 months' duration or less were tested for antibodies against the flavoprotein subunit of succinate dehydrogenase. Clinical data were obtained by retrospective review of patients' charts. Enzyme linked immunosorbent assay was used to test sera for serum antibodies against purified succinate dehydrogenase. RESULTS: 38 patients with TAO and 32 healthy age and sex matched controls were included in the study. Anti-flavoprotein antibodies were detected in 24 out of 38 patients with TAO (63.16%) and in five out of 32 healthy controls (15.63%) (p<0.01). Neither age, sex, duration of thyroid disease, thyroid status, treatment of thyroid disease, smoking history, duration of orbitopathy, activity of orbitopathy, nor the presence of lid retraction were significantly associated with the presence of serum anti-flavoprotein antibodies (p>0.05). However, the total number of rectus muscles affected in both eyes of the patients was significantly correlated with the finding of a positive antibody test (p<0.05). CONCLUSIONS: Serum antibodies reactive with the flavoprotein subunit of succinate dehydrogenase are associated with extraocular muscle involvement in active TAO of recent onset.

Low-dose radiotherapy for lymphoid lesions of the orbit and ocular adnexa.

PURPOSE: There is no agreement within the radiation oncology and ophthalmic communities regarding the treatment of lymphoid lesions of the orbit and ocular adnexa. The authors report their experience with the use of low-dose radiation therapy for malignant and benign lymphoid masses of the orbital region in a series of 54 patients treated between 1985 and 1993. METHODS: All patients received 2 Gy per day for a total of 24 Gy, except when the lesion was extensive, in which case the therapy was 1.5 Gy per day for a total of 25.5 Gy. A diagnosis was established by incisional surgical biopsy in 26 patients and aspiration cytology in 28 patients. Those with a malignant or an indeterminate diagnosis were evaluated with a modified Ann Arbor staging system. RESULTS: Low-dose radiation therapy produced a complete response in 100% of the orbital lymphoid lesions. This local control was maintained in 52 patients (96%) for the first year and in 51 patients (95%) for 5 or more years with a mean follow-up of 7 years. One patient died of causes unrelated to the malignant lymphoma after the first year of observation. The mean age of the 54 patients was 67 years, and the range was 37 to 90 years. The mean ages of presentation for each location were: orbit, 67 years; conjunctiva, 68 years; lacrimal gland, 66 years; and eyelids, 72 years. The female-to-male ratio was 1.25:1 (34 women and 20 men). In this series, 9 patients had benign processes, 38 patients had non-Hodgkin's lymphoma, and 7 patients had abnormalities of indeterminate cause. All histologic subtypes of non-Hodgkin's lymphoma involving the orbit responded equally well to therapy. Forty-five patients had clinically staged disease as follows: stage I, 21 patients; stage II, 4 patients; stage III, 2 patients; and stage IV, 18 patients. Benign disease, diagnosed in 9 patients, was not staged. CONCLUSION: Low-dose radiation therapy proved effective in treating lymphoid lesions of the orbital area. No treatment-limiting complications occurred. The only early side effects were mild xerophthalmia and chemosis in 50% of patients, and the only chronic side effect was mild xerophthalmia in 33% of patients. Cataracts, corneal ulcerations, and retinal injury were not observed.

A 63 kDa skeletal muscle protein associated with eye muscle inflammation in Graves' disease is identified as the calcium binding protein calsequestrin.

It is generally accepted that thyroid-associated ophthalmopathy (TAO) is an autoimmune disease of the eye muscle (EM) and the surrounding orbital connective tissue in which circulating antibodies play an important role. Antibodies against EM membrane proteins of 63-67kDa mol. wt. seem to be the best markers of ophthalmopathy in patients with autoimmune thyroid disease. We purified a 63 kDa EM protein using SDS-polyacrylamide gel electrophoresis technology and TAO patients' sera as probes, digested the protein with cyanogen bromide and sequenced immunoreactive peptides. We also screened a human EM library with a rabbit antiserum against 63-65 kDa proteins and affinity purified antibodies from a TAO patient's serum that reacted with a 55 kDa EM membrane protein. From partial sequence information and from DNA sequencing of positive cDNA clones, the protein was identified as calsequestrin, a 63 kDa calcium binding protein localized in the sarcoplasmic reticulum of the muscle fiber. As determined by Northern blotting, calsequestrin was expressed in EM and other skeletal muscle but not thyroid or fibroblasts. Calsequestrin is different from the "64 kDa protein", which has been identified as succinate dehydrogenase flavoprotein subunit, which has a corrected mol. wt. of 67 kDa. Serum antibodies against calsequestrin were found in 40% of patients with clinically active TAO, but in only 4% of those with stable eye disease, and in 5% of normal subjects, by immunoblotting. Although it is possible that autoimmunity against calsequestrin plays a role in the progressive EM damage that characterizes ophthalmopathy it is more likely that the antibodies are secondary to a reaction against some other cell membrane protein, such as the novel thyroid and eye muscle shared protein G2s or the TSH receptor.

Liposarcoma of the orbit: a management challenge.

A previously healthy 35-year-old man experiencing slowly progressive, painless proptosis of the right eye. Visual function was normal, but supraduction was limited. Computed tomography revealed a superior, extraconal orbital mass. Subtotal excision was performed, and a diagnosis of liposarcoma was rendered only with expert analysis. Despite subsequent orbital exenteration and postoperative radiation, a local recurrence developed 5 years later. The clinical features that predict recurrence, and management options that may promote longevity, are discussed.

The posterior inferior orbitotomy.

Four patients with orbital apex tumors between the optic nerve and inferior rectus underwent a posterior inferior orbitotomy through the maxillary sinus. Three tumors were removed successfully and the fourth was not located, but the visual function improved after surgery, presumably owing to decompression of the posterior orbital floor. The technique was carried out through a standard Caldwell-Luc approach through the maxillary sinus. The posterior inferior orbital wall was removed and the inferior rectus was retracted either laterally or medially to gain access to the tumor, which was removed microsurgically. The authors believe this approach provides a reasonably safe alternative to remove small, well-circumscribed, inferior posterior orbital apical tumors. It also avoids dissection through the orbit from other directions with the inherent risks of damaging overlying vital structures.

Eye muscle antibodies in patients with ocular myasthenia gravis: possible mechanism for eye muscle inflammation in acetylcholine-receptor antibody-negative patients.

Myasthenia gravis is an organ-specific autoimmune disorder generally thought to be caused by an antibody-mediated attack against the skeletal muscle nicotinic acetylcholine (Ach) receptor (AchR) at the neuromuscular junction. Extraocular muscle weakness and double vision are present in about 90% of patients with myasthenia gravis and are the predominant complaints in about 20% of patients, when the condition is called ocular myasthenia gravis (OMG). While serum antibodies against the AchR are detected in most patients with generalized myasthenia gravis (GMG), they are not found in about one-third of patients with the ocular variety, and epidemiological, clinical, and serological studies suggest that OMG and GMG are two separate diseases. Both forms of myasthenia gravis are sometimes associated with thyroid autoimmunity or thyroid-associated ophthalmopathy (TAO). We have therefore tested the sera of patients with GMG and OMG by Western blotting for antibodies against porcine eye muscle membrane proteins in general, and by enzyme-linked immunosorbent assays (ELISA) specifically for reaction with two skeletal muscle antigens which are prominent marker antigens for TAO, namely, the calcium-binding protein calsequestrin and the so-called "64-kDa protein." The 64-kDa protein has recently been identified as the flavoprotein subunit of mitochondrial succinate dehydrogenase. Patients with ophthalmopathy and myasthenia were excluded. Nine of the patients had associated Graves' hyperthyroidism without evident ophthalmopathy and one had Hashimoto's thyroiditis. Antibodies against porcine eye muscle membrane antigens of M(r) 15-110 kDa were detected in patients with GMG or OMG, one or more antibodies being detected in 100% of patients with GMG and in 88% of those with OMG. The most frequently found antibodies were those targeting eye muscle membrane proteins of 15, 67, and 110 kDa. Antibodies reactive with purified calsequestrin (63 kDa) were detected in 21% of patients with OMG but in no patient with GMG. Antibodies recognizing purified succinate dehydrogenase (67 kDa) were found in 42% of patients with OMG, in 100% (5 of 5) of patients with GMG, and in 48% of all patients with myasthenia gravis not associated with Graves' hyperthyroidism. There was no close correlation between any eye muscle-reactive antibody and antibodies against the AchR in either group of myasthenic patients. The findings support the notion that immunoreactivity against skeletal muscle proteins other than the AchR may play a role in the development of the muscle weakness in AchR antibody-negative patients with OMG and GMG, although it is unlikely that any of the antibodies demonstrated in this study are directly implicated. Similarly, while the demonstration of antibodies reactive with eye muscle antigens associated with TAO in patients with OMG raises the possibility that the link between the ocular lesions of myasthenia gravis and Graves' disease may be autoimmunity against a common antigen(s), it is more likely that both disorders are mediated by cytotoxic T cells recognizing another cell membrane antigen, such as the novel thyroid and eye muscle shared protein G2s, and that serum antibodies reactive with succinate dehydrogenase Fp subunit and calsequestrin are markers of an immune-mediated eye muscle reaction.

T cell interactions with extracellular matrix proteins in patients with thyroid-associated ophthalmopathy.

Although thyroid-associated ophthalmopathy (TAO) is now generally accepted as an autoimmune inflammatory disorder of the extraocular muscles and the orbital connective tissue, its aetiopathogenesis remains poorly understood. Recent data indicate that impaired interactions between T cells and extracellular matrix (ECM) proteins may play an important role in development and maintaining of an inflammatory process. We report here results of the study focusing on interactions between T lymphocytes and collagen-I (Coll-I), collagen-IV (Coll-IV), fibronectin (FN), laminin (LM) in patients with TAO. Using a standard peripheral blood mononuclear cells (PBMC) proliferation assay, we observed a markedly enhanced T cell response to Coll-I in patients with active TAO (mean SI=4.5). The proliferatory response to Coll-I was significantly greater (Wilcoxon test; p < 0.001) than in normal subjects (mean SI=1.88), patients with stable TAO (mean SI=2.05) and patients with thyroid autoimmune diseases (AITD) without ophthalmopathy (mean SI=2.49). PBMC stimulation by Coll-I is likely to be antigen-dependent requiring engagement of the T cell receptor with collagen peptides, rather than mediated via integrins. The percentage of circulating CD29+ (beta1 integrin chain) T cells was not increased in patients with active TAO. Additionally in the assay of costimulation of CD3-mediated proliferation, we found that peripheral blood T cells from patients with TAO and AITD were costimulated only by FN. On the other hand a markedly enhanced costimulation of CD3-mediated proliferative responses by Coll-I, Coll-IV, FN and LM were observed in a retrobulbar T cell line. We conclude that abnormalities in T cell interactions with ECM proteins, especially Coll-I may play a role in the pathogenesis of TAO.

Reevaluation of the prevalences of serum autoantibodies reactive with "64-kd eye muscle proteins" in patients with thyroid-associated ophthalmopathy.

Serum autoantibodies reactive with eye muscle proteins of "64 kilodaltons (kd)" are frequently found in patients with Graves' hyperthyroidism and thyroid-associated ophthalmopathy (TAO). Earlier, we cloned a 64-kd protein that was identified as calsequestrin, a calcium-binding protein localized in the sarcoplasmic reticulum of striated muscle and extensively studied another cloned 64-kd protein, called 1D, which is expressed in thyroid and eye muscle, and some other tissues. Using a monoclonal antibody against calsequestrin, a polyclonal antibody against 1D and a TAO patient serum reactive with the "64-kd protein," as probes, we performed Western blots of porcine eye muscle membrane. We identified three different proteins in the 63 to 67 kd molecular weight range that were targeted by antibodies in sera from patients with TAO. It was not possible to differentiate antibodies reactive with calsequestrin and 1D because these two proteins have very similar molecular weights--63 to 64 kd--and band appearance in Western blotting. A 67-kd protein was most frequently recognized by TAO patients' sera. Serum antibodies reactive with the 67-kd protein were detected in 73% of patients with active TAO of 1 year duration or less, in 37% of patients with TAO of more than 3 years' duration, in 35% with Graves' hyperthyroidism without evident ophthalmopathy, in 30% of patients with Hashimoto's thyroiditis, and in 16% of normal subjects. Serum antibodies reactive with calsequestrin/1D were detected in 47% of patients with active TAO of less than 1 year, in 22% of patients with TAO longer than 3 years, 17% with Graves' hyperthyroidism without evident ophthalmopathy, in 10% of patients with Hashimoto's thyroiditis, and in 21% of normal subjects. The prevalence of anti-67-kd protein antibodies in TAO patients corresponded to those reactive with the so called "64-kd protein" that we have reported previously. In conclusion, we were able to improve the accuracy of the Western blots by comparing the molecular weight of positive bands using specific antibodies reactive with eye muscle antigens as probes. The previously recognized, and extensively studied, "64-kd protein" is now shown to have a molecular weight of 67 kd. The role of the various eye muscle antibodies in the diagnosis and management of the ophthalmopathy associated with Graves' hyperthyroidism needs to be addressed in prospective studies using purified or recombinant full-length proteins.

Solitary fibrous tumor of the orbit.

Solitary fibrous tumor (SFT) of the orbit is a very rare lesion that may be misdiagnosed as fibrous histiocytoma, hemangiopericytoma, or other orbital tumors. We present a 62-year-old man who presented with painless proptosis, 20 years following left eye enucleation for a presumed neurofibroma. On T2-weighted magnetic resonance imaging (MRI), a hypointense tumor almost filled his entire left orbit. There was no intracranial extension. The specimen obtained at orbital exenteration was consistent with the histologic, immunohistochemical, and electron microscopic findings of SFT. The tumor was positive for vimentin and CD34 staining but negative for S-100 protein and epithelial membrane antigen. Only nine other cases of SFT of the orbit have been documented in the literature. Recognition of SFT of the orbit as a distinct pathologic entity and further follow-up of published cases are needed to determine the prognosis of this rare lesion.

The 64-kilodalton eye muscle protein is the flavoprotein subunit of mitochondrial succinate dehydrogenase: the corresponding serum antibodies are good markers of an immune-mediated damage to the eye muscle in patients with Graves' hyperthyroidism.

Thyroid-associated ophthalmopathy (TAO) is a progressive eye disorder associated with thyroid autoimmunity, particularly Graves' hyperthyroidism, which is generally considered to have an autoimmune etiology. Eye muscle membrane proteins reportedly of 55 and 64 kDa are the best markers of the ophthalmopathy. The main focus of our recent studies has been to purify the pertinent proteins from porcine eye muscle membranes and characterize them. The 64-kDa protein is now shown from a partial sequence and by Western blotting using specific antibody probes to be the flavoprotein (Fp) subunit of succinate dehydrogenase and to have a correct molecular mass of 67 kDa. The protein was purified and cleaved with cyanogen bromide, and the N-terminal region of an immunoreactive partial peptide was determined. The 20-amino acid porcine sequence so obtained matched one within the Fp subunits of human and bovine succinate dehydrogenases in 20 and 18 of these positions, respectively. Succinate dehydrogenase is both a citric acid cycle enzyme and a component (complex II) of the mitochondrial respiratory chain. It is thus essential for aerobic energy production and is highly conserved. The mature human and bovine Fp subunits are 92% homologous and have a molecular mass of approximately 67 kDa, the same as our redetermined value for the 64-kDa marker protein. Sera from patients with TAO and from those with Graves' hyperthyroidism without evident ophthalmopathy highlighted the 64-kDa marker protein in crude porcine eye muscle membranes and the Fp subunit of highly purified bovine succinate dehydrogenase at the identical position on Western blots. Anti-beef Fp antibodies were detected in sera from 67% of patients with active TAO of more than 1-yr duration, in 30% with stable TAO of more than 3-yr duration, and in 30% of patients with Graves' hyperthyroidism without ophthalmopathy, but in only 7% of age- and sex-matched normal subjects. As succinate dehydrogenase is bound to the matrix (inside) surface of the mitochondrial inner membrane, it is unlikely to be accessible to circulating autoantibodies. We would postulate that eye muscle damage in ophthalmopathy is probably caused by cytotoxic antibodies or CD+ T lymphocytes targeting a cell membrane antigen, such as the thyroid and eye muscle shared protein G2s, and that presentation of succinate dehydrogenase is secondary. On the other hand, an autoantibody response to succinate dehydrogenase may be a good marker of immune-mediated damage to the eye muscle fiber and may support the idea that the extraocular muscles are targets of the autoimmune reactions of TAO.

Use of dsRNA-mediated genetic interference to demonstrate that frizzled and frizzled 2 act in the wingless pathway.

We investigated the potential of double-stranded RNA to interfere with the function of genes in Drosophila. Injection of dsRNA into embryos resulted in potent and specific interference of several genes that were tested. In contrast, single-stranded RNA weakly interfered with gene activity. The method was used to determine the reception mechanism of the morphogen Wingless. Interference of the frizzled and Drosophila frizzled 2 genes together produced defects in embryonic patterning that mimic loss of wingless function. Interference of either gene alone had no effect on patterning. Epistasis analysis indicates that frizzled and Drosophila frizzled 2 act downstream of wingless and upstream of zeste-white3 in the Wingless pathway. Our results demonstrate that dsRNA interference can be used to analyze many aspects of gene function.

Role of eye muscle antibody measurement in diagnosis of thyroid-associated ophthalmopathy: a laboratory update.

OBJECTIVE: To review the current role of measurement of serum eye muscle antibodies in thyroid-associated ophthalmopathy (TAO). METHODS: We conducted laboratory studies to determine the prevalences of serum autoantibodies reactive with eye muscle antigens in patients with active and inactive TAO, Graves' hyperthyroidism, and Hashimoto's thyroiditis as well as in normal subjects. RESULTS: The two antigens most often recognized in immunoblotting with crude human or porcine eye muscle membranes by serum autoantibodies in patients with TAO are eye muscle membrane proteins of 55 and 64 kd. One 64-kd eye muscle protein has recently been cloned by screening a human eye muscle expression library with two different antibody probes and identified from a computer gene bank search as the calcium-binding protein calsequestrin. A fragment of a 220-kd eye muscle protein, called G2s, has also been cloned by screening the eye muscle library with affinity-purified antibodies reactive with a 55-kd eye muscle membrane protein. The prevalences of autoantibodies reactive with these two antigens in our study groups were as follows. Antibodies against calsequestrin were detected in 38% of patients with TAO for <1 year, in 17% of those with TAO for >3 years, in 17% of patients with Graves' hyperthyroidism without ophthalmopathy, in 12% of patients with Hashimoto's thyroiditis without ophthalmopathy, and in 21% of normal subjects. Antibodies reactive with the 64-kd protein were demonstrated in 62% of patients with recent-onset active TAO, in 33% with eye disease for >3 years, in 39% of patients with Graves' hyperthyroidism without ophthalmopathy, in 25% of patients with Hashimoto's thyroiditis, and in 16% of normal control subjects. Antibodies reactive with G2s fusion protein were detected in 67% of patients with recent-onset active TAO, in 46% of patients with Graves' hyperthyroidism, and in 20% of normal subjects. Antibodies reactive with the parent protein, of which G2s is a fragment, may be markers of early eye muscle swelling and inflammation, whereas those reactive with the 64-kd protein and, less often, calsequestrin are associated with established eye disease. CONCLUSION: Measurement of serum eye muscle antibodies is recommended as an aid to the early diagnosis of ophthalmopathy in predisposed patients and first-degree relatives of patients with TAO as well as to monitor active or progressive eye disease.

The evaluation and treatment of extraocular motility deficits.

Binocular diplopia, monocular diplopia and oscillopsia may be manifestations of skull base lesions or may result from skull base surgery. An ophthalmologic perspective on the diagnosis and treatment of these extraocular motility deficits is reviewed.

The prevalence and implications of ocular hypertension and glaucoma in thyroid-associated orbitopathy.

PURPOSE: The authors determined the prevalence of ocular hypertension and its association with progression to glaucomatous damage in patients with thyroid-associated orbitopathy (TAO). METHODS: The charts of 500 consecutive patients with TAO seen at the Allegheny General Hospital (Pittsburgh, PA) between 1985 and 1995 were analyzed. The amount of proptosis, degree and duration of myopathy, exposure to corticosteroids, prior glaucoma treatment, and family history of glaucoma were evaluated. RESULTS: One hundred twenty (24%) patients with TAO were noted to have an intraocular pressure (IOP) greater than 22 mmHg but less than 30 mmHg. This ocular hypertensive group was composed of 34 men and 86 women with a mean age of 55 years and mean follow-up of 4 years. Seven patients were defined as glaucoma suspects, based on increased but nonprogressive cup-to-disc ratios or nonprogressive, atypical visual field changes in the presence of increased IOP. Two patients demonstrated progressive visual field abnormalities and cupping. Of the factors evaluated, only the duration of active orbital involvement was statistically associated with progression to glaucomatous damage. The mean duration of TAO was 3, 8, and 12 years for ocular hypertensives, glaucoma suspects, and glaucomatous damage, respectively. CONCLUSIONS: Only a prolonged duration of active TAO in association with ocular hypertension correlated with progression to glaucomatous damage. These patients with chronic TAO deserve special attention and close follow-up to prevent optic nerve damage.