The popularization of ophthalmic endoscopy has been promoted by recent technological advancements that increase the number of indications for endoscopy. These advancements have improved the endoscope's capabilities in its two fundamental surgical advantages: (1) bypassing anterior segment opacities, and (2) visualizing anteriorly positioned structures such as the ciliary bodies and sub-iris space. In this article, the current state of the ophthalmic endoscope is reviewed alongside its growing number of applications in glaucoma, vitreoretinal, and ocular trauma surgery. We describe the role of endoscopy in endocyclophotocoagulation for glaucoma, cyclitic membrane peeling in hypotony, retinal detachment surgery, intraocular foreign body removal, severe endophthalmitis, and pediatric traumatic vitreoretinal surgery. This review examines both the pearls and limitations of the ophthalmic application of endoscopy. In doing so, we hope to provide guidelines for using the endoscope and also to highlight applications of endoscopy that merit further study.
Subretinal injection of sodium hyaluronate is a widely accepted method of inducing retinal detachment (RD). However, the height and duration of RD or the occurrence of subretinal hemorrhage can affect photoreceptor cell death in the detached retina. Hence, it is advantageous to create reproducible RDs without subretinal hemorrhage for evaluating photoreceptor cell death. We modified a previously reported method to create bullous and persistent RDs in a reproducible location with rare occurrence of subretinal hemorrhage. The critical step of this modified method is the creation of a self-sealing scleral incision, which can prevent leakage of sodium hyaluronate after injection into the subretinal space. To make the self-sealing scleral incision, a scleral tunnel is created, followed by scleral penetration into the choroid with a 30 G needle. Although choroidal hemorrhage may occur during this step, astriction with a surgical spear reduces the rate of choroidal hemorrhage. This method allows a more reproducible and reliable model of photoreceptor death in diseases that involve RD such as rhegmatogenous RD, retinopathy of prematurity, diabetic retinopathy, central serous chorioretinopathy, and age-related macular degeneration (AMD). [corrected].
BACKGROUND: Interaction of transmembrane mucins with the multivalent carbohydrate-binding protein galectin-3 is critical to maintaining the integrity of the ocular surface epithelial glycocalyx. This study aimed to determine whether disruption of galectin-3 multimerization and insertion of synthetic glycopolymers in the plasma membrane could be used to modulate glycocalyx barrier function in corneal epithelial cells. METHODOLOGY/PRINCIPAL FINDINGS: Abrogation of galectin-3 biosynthesis in multilayered cultures of human corneal epithelial cells using siRNA, and in galectin-3 null mice, resulted in significant loss of corneal barrier function, as indicated by increased permeability to the rose bengal diagnostic dye. Addition of β-lactose, a competitive carbohydrate inhibitor of galectin-3 binding activity, to the cell culture system, transiently disrupted barrier function. In these experiments, treatment with a dominant negative inhibitor of galectin-3 polymerization lacking the N-terminal domain, but not full-length galectin-3, prevented the recovery of barrier function to basal levels. As determined by fluorescence microscopy, both cellobiose- and lactose-containing glycopolymers incorporated into apical membranes of corneal epithelial cells, independently of the chain length distribution of the densely glycosylated, polymeric backbones. Membrane incorporation of cellobiose glycopolymers impaired barrier function in corneal epithelial cells, contrary to their lactose-containing counterparts, which bound to galectin-3 in pull-down assays. CONCLUSIONS/SIGNIFICANCE: These results indicate that galectin-3 multimerization and surface recognition of lactosyl residues is required to maintain glycocalyx barrier function at the ocular surface. Transient modification of galectin-3 binding could be therapeutically used to enhance the efficiency of topical drug delivery.
The conjunctiva is a moist mucosal membrane that is constantly exposed to an array of potential pathogens and triggers of inflammation. The NACHT, leucine rich repeat (LRR), and pyrin domain-containing protein 3 (NLRP3) is a Nod-like receptor that can sense pathogens or other triggers, and is highly expressed in wet mucosal membranes. NLRP3 is a member of the multi-protein complex termed the NLRP3 inflammasome that activates the caspase 1 pathway, inducing the secretion of biologically active IL-1β, a major initiator and promoter of inflammation. The purpose of this study was to: (1) determine whether NLRP3 is expressed in the conjunctiva and (2) determine whether goblet cells specifically contribute to innate mediated inflammation via secretion of IL-1β. We report that the receptors known to be involved in the priming and activation of the NLRP3 inflammasome, the purinergic receptors P2X4 and P2X7 and the bacterial Toll-like receptor 2 are present and functional in conjunctival goblet cells. Toxin-containing Staphylococcus aureus (S. aureus), which activates the NLRP3 inflammasome, increased the expression of the inflammasome proteins NLRP3, ASC and pro- and mature caspase 1 in conjunctival goblet cells. The biologically active form of IL-1β was detected in goblet cell culture supernatants in response to S. aureus, which was reduced when the cells were treated with the caspase 1 inhibitor Z-YVAD. We conclude that the NLRP3 inflammasome components are present in conjunctival goblet cells. The NRLP3 inflammasome appears to be activated in conjunctival goblet cells by toxin-containing S. aureus via the caspase 1 pathway to secrete mature IL1-β. Thus goblet cells contribute to the innate immune response in the conjunctiva by activation of the NLRP3 inflammasome.
Most isolates of Toxoplasma from Europe and North America fall into one of three genetically distinct clonal lineages, the type I, II and III lineages. However, in South America these strains are rarely isolated and instead a great variety of other strains are found. T. gondii strains differ widely in a number of phenotypes in mice, such as virulence, persistence, oral infectivity, migratory capacity, induction of cytokine expression and modulation of host gene expression. The outcome of toxoplasmosis in patients is also variable and we hypothesize that, besides host and environmental factors, the genotype of the parasite strain plays a major role. The molecular basis for these differences in pathogenesis, especially in strains other than the clonal lineages, remains largely unexplored. Macrophages play an essential role in the early immune response against T. gondii and are also the cell type preferentially infected in vivo. To determine if non-canonical Toxoplasma strains have unique interactions with the host cell, we infected murine macrophages with 29 different Toxoplasma strains, representing global diversity, and used RNA-sequencing to determine host and parasite transcriptomes. We identified large differences between strains in the expression level of known parasite effectors and large chromosomal structural variation in some strains. We also identified novel strain-specifically regulated host pathways, including the regulation of the type I interferon response by some atypical strains. IFNβ production by infected cells was associated with parasite killing, independent of interferon gamma activation, and dependent on endosomal Toll-like receptors in macrophages and the cytoplasmic receptor retinoic acid-inducible gene 1 (RIG-I) in fibroblasts.
PURPOSE: To investigate the immunohistochemical features of ocular adnexal pleomorphic adenoma and adenoid cystic carcinoma. DESIGN: Retrospective clinicopathologic study. METHODS: Clinical records and microscopic slides of 7 cases of each tumor type were reviewed. Immunohistochemical probes for Ki-67 and p53, and newer nuclear markers MYB for adenoid cystic carcinoma and PLAG1 for pleomorphic adenoma, were employed. RESULTS: Pleomorphic adenomas were asymptomatic, whereas adenoid cystic carcinomas were painful. No pleomorphic adenomas recurred; 4 adenoid cystic carcinomas recurred, resulting in 3 deaths. Unusual histopathologic variants for which immunohistochemistry proved useful included a myoepithelioma, an atypical pleomorphic adenoma, tubular and solid/basaloid variants of adenoid cystic carcinoma, and a morphologically heterogeneous adenoid cystic carcinoma of a Wolfring gland. For the pleomorphic adenomas, the average Ki-67 proliferation index was 3.8%; p53 was weakly staining, with an average positivity of 18.5%; PLAG1 was strongly positive in all cases; MYB was negative in 5 cases and weakly focally positive in 2 cases. For the adenoid cystic carcinomas, the average Ki-67 proliferation index was 29.1%; p53 stained positively and strongly with an average of 39%; none stained positively for PLAG1; and 6 out of 7 were MYB positive. CONCLUSIONS: Between pleomorphic adenoma and adenoid cystic carcinoma, there was no overlap in Ki-67 positivity. Positivity for p53 showed overlap in only one lesion of each type. PLAG1 and MYB positivity were highly discriminating between pleomorphic adenoma and adenoid cystic carcinoma. Immunohistochemical analysis should be investigated further for its role in the evaluation of pleomorphic adenoma and adenoid cystic carcinoma.
Nevus comedonicus is a rare developmental abnormality of the infundibulum of the hair follicle. It is usually unilateral and commonly presents at birth or during childhood. A rare case of late-onset, bilateral nevus comedonicus of the eyelids is reported. A 79-year-old man presented with asymptomatic but disfiguring eyelid lesions noted several months earlier. On physical examination, multiple papules resembling comedones were present bilaterally in the eyelids, canthi, temple regions, and bridge of the nose. Microscopically, there were deep invaginations of the follicular canals forming focal tunnels or pseudosinus tracts with poral openings to the surface. These variably cystic structures were lined by keratinizing and nonkeratinizing squamous epithelium, contained concentric lamellae of keratin in their lumens, and some were acutely or chronically inflamed. The diagnosis of a nevus comedonicus was made. The clinical and histopathologic characteristics, pathogenesis, differential diagnosis, and management of nevus comedonicus are briefly discussed.
Streptococcus pneumoniae is a pathogen associated with a range of invasive and noninvasive infections. Despite the identification of the majority of virulence factors expressed by S. pneumoniae, knowledge of the strategies used by this bacterium to trigger infections, especially those originating at wet-surfaced epithelia, remains limited. In this regard, we recently reported a mechanism used by a nonencapsulated, epidemic conjunctivitis-causing strain of S. pneumoniae (strain SP168) to gain access into ocular surface epithelial cells. Mechanistically, strain SP168 secretes a zinc metalloproteinase, encoded by a truncated zmpC gene, to cleave off the ectodomain of a vital defense component - the membrane mucin MUC16 - from the apical glycocalyx barrier of ocular surface epithelial cells and, thereby invades underlying epithelial cells. Here, we compare the truncated SP168 ZmpC to its highly conserved archetype from S. pneumoniae serotype 4 (TIGR4), which has been linked to pneumococcal virulence in previous studies. Comparative nucleotide sequence analyses revealed that the zmpC gene corresponding to strain SP168 has two stretches of DNA deleted near its 5' end. A third 3 bp in-frame deletion, resulting in the elimination of an alanine residue, was found towards the middle segment of the SP168 zmpC. Closer examination of the primary structure revealed that the SP168 ZmpC lacks the canonical LPXTG motif - a signature typical of several surface proteins of gram-positive bacteria and of other pneumococcal zinc metalloproteinases. Surprisingly, in vitro assays performed using recombinant forms of ZmpC indicated that the truncated SP168 ZmpC induces more cleavage of the MUC16 ectodomain than its TIGR4 counterpart. This feature may help explain, in part, why S. pneumoniae strain SP168 is better equipped at abrogating the MUC16 glycocalyx barrier en route to causing epidemic conjunctivitis.
PURPOSE: To present the current understanding of age-related macular degeneration (AMD) pathogenesis, based on clinical evidence, epidemiologic data, histopathologic examination, and genetic data; to provide an update on current and emerging therapies; and to propose an integrated model of the pathogenesis of AMD. DESIGN: Review of published clinical and experimental studies. METHODS: Analysis and synthesis of clinical and experimental data. RESULTS: We are closer to a complete understanding of the pathogenesis of AMD, having progressed from clinical observations to epidemiologic observations and clinical pathologic correlation. More recently, modern genetic and genomic studies have facilitated the exploration of molecular pathways. It seems that AMD is a complex disease that results from the interaction of genetic susceptibility with aging and environmental factors. Disease progression also seems to be driven by a combination of genetic and environmental factors. CONCLUSIONS: Therapies based on pathophysiologic features have changed the paradigm for treating neovascular AMD. With improved understanding of the underlying genetic susceptibility, we can identify targets to halt early disease and to prevent progression and vision loss.
UNLABELLED: The vascular beds supplying the retina may sustain injury as a result of underlying disease such as diabetes, and/or the interaction of genetic predisposition, environmental insults, and age. The vascular pathologic features observed in different intraocular vascular diseases can be categorized broadly as proliferation, exemplified by proliferative diabetic retinopathy, leakage such as macular edema secondary to retinal vein occlusion, or a combination of proliferation and leakage, as seen in neovascular age-related macular degeneration (AMD). The World Health Organization has identified diabetic retinopathy and AMD as priority eye diseases for the prevention of vision loss in developed countries. The pathologic transformations of the retinal vasculature seen in intraocular vascular disease are associated with increased expression of vascular endothelial growth factor A (VEGF), a potent endothelial-specific mitogen. Furthermore, in model systems, VEGF alone is sufficient to trigger intraocular neovascularization, and its inhibition is associated with functional and anatomic improvements in the affected eye. Therapeutic interventions with effect on VEGF include intraocular capture and neutralization by engineered antibodies or chimeric receptors, downregulation of its expression with steroids, or alleviation of retinal ischemia, a major stimulus for VEGF expression, with retinal ablation by laser treatment. Data from prospective randomized clinical trials indicate that VEGF inhibition is a potent therapeutic strategy for intraocular vascular disease. These findings are changing clinical practice and are stimuli for further study of the basic mechanisms controlling intraocular angiogenesis. FINANCIAL DISCLOSURE(S): Proprietary or commercial disclosure may be found after the references.
BACKGROUND: The vertebrate retina comprises sensory neurons, the photoreceptors, as well as many other types of neurons and one type of glial cell. These cells are generated by multipotent and restricted retinal progenitor cells (RPCs), which express Notch1. Loss of Notch1 in RPCs late during retinal development results in the overproduction of rod photoreceptors at the expense of interneurons and glia. RESULTS: To examine the molecular underpinnings of this observation, microarray analysis of single retinal cells from wild-type or Notch1 conditional knockout retinas was performed. In situ hybridization was carried out to validate some of the findings. CONCLUSIONS: The majority of Notch1-mutant cells lost expression of known Notch target genes. These cells also had low levels of RPC and cell cycle genes, and robustly up-regulated rod precursor genes. In addition, single wild-type cells, in which cell cycle marker genes were down-regulated, expressed markers of both rod photoreceptors and interneurons.
Photoreceptor cell death is the ultimate cause of vision loss in various retinal disorders, including retinal detachment (RD). Photoreceptor cell death has been thought to occur mainly through apoptosis, which is the most characterized form of programmed cell death. The caspase family of cysteine proteases plays a central role for inducing apoptosis, and in experimental models of RD, dying photoreceptor cells exhibit caspase activation; however, there is a paradox that caspase inhibition alone does not provide a sufficient protection against photoreceptor cell loss, suggesting that other mechanisms of cell death are involved. Recent accumulating evidence demonstrates that non-apoptotic forms of cell death, such as autophagy and necrosis, are also regulated by specific molecular machinery, such as those mediated by autophagy-related proteins and receptor-interacting protein kinases, respectively. Here we summarize the current knowledge of cell death signaling and its roles in photoreceptor cell death after RD and other retinal degenerative diseases. A body of studies indicate that not only apoptotic but also autophagic and necrotic signaling are involved in photoreceptor cell death, and that combined targeting of these pathways may be an effective neuroprotective strategy for retinal diseases associated with photoreceptor cell loss.
Graft versus host disease (GVHD) is a common complication of allogeneic stem cell transplantation (allo-SCT). Ocular GVHD develops in approximately 40-60% of patients following allo-SCT and its most common clinical manifestations include keratoconjunctivitis sicca and cicatricial conjunctivitis. Ocular GVHD may lead to severe ocular surface disease, which can significantly diminish quality of life and restrict daily activities. It is thus important to monitor the condition closely since with timely diagnosis, irreversible damage can be avoided. The current review will focus on updated information regarding ocular GVHD.
BACKGROUND: The purpose of this report is to describe the association of severe anterior uveitis with type II essential cryoglobulinemia. FINDINGS: A 40-year-old male with a history of psoriatic arthritis presented with severe anterior uveitis associated with type II essential cryoglobulinemia. His uveitis, refractory to steroid treatments, was well controlled following treatments for cryoglobulinemia. The temporal association between his cryoglobulinemia and uveitis, combined with his improved visual acuity and inflammation after plasmapheresis and rituximab infusions, suggests cryoglobulinemia to be the underlying condition of his uveitis. CONCLUSIONS: To our best knowledge, this is the first reported case of anterior uveitis secondary to type II essential cryoglobulinemia.
PURPOSE: Intraocular pressure (IOP) regulation is largely unknown. SPARC-null mice demonstrate a lower IOP resulting from increased outflow. SPARC is a matricellular protein often associated with fibrosis. We hypothesized that SPARC overexpression would alter IOP by affecting extracellular matrix (ECM) synthesis and/or turnover in the trabecular meshwork (TM). METHODS: An adenoviral vector containing human SPARC was used to increase SPARC expression in human TM endothelial cells and perfused human anterior segments using multiplicities of infection (MOIs) 25 or 50. Total RNA from TM was used for quantitative PCR, while protein from cell lysates and conditioned media were used for immunoblot analyses and zymography. After completion of perfusion, the anterior segments were fixed, sectioned, and examined by light and confocal microscopy. RESULTS: SPARC overexpression increased the IOP of perfused human anterior segments. Fibronectin and collagens IV and I protein levels were elevated in both TM cell cultures and within the juxtacanalicular (JCT) region of perfused anterior segments. Collagen VI and laminin protein levels were increased in TM cell cultures but not in perfused anterior segments. The protein levels of pro-MMP-9 decreased while the kinetic inhibitors of metalloproteinases, TIMP-1 and PAI-1 protein levels, increased at MOI 25. At MOI 50, the protein levels of pro-MMP-1, -3, and -9 also decreased while PAI-1 and TIMP-1 and -3 increased. Only MMP-9 activity was decreased on zymography. mRNA levels of the collagens, fibronectin, and laminin were not affected by SPARC overexpression. CONCLUSIONS: SPARC overexpression increases IOP in perfused cadaveric human anterior segments resulting from a qualitative change the JCT ECM. Selective decrease of MMP-9 activity is likely part of the mechanism. SPARC is a regulatory node for IOP.
Glaucoma is a leading cause of irreversible blindness. Intraocular pressure (IOP) is the only modifiable risk factor for glaucoma, yet there is little known about the molecular events that regulate IOP. Genetic and genomic studies have helped identify genes that influence IOP and could lead to the identification of biological pathways that serve as targets for novel pressure-modifying therapies. Genetic linkage studies resulted in the identification of several genes that cause Mendelian (autosomal dominant or autosomal recessive) forms of high-pressure glaucoma, including MYOC. PITX2, FOXC1, and CYP1B1. Classical twin studies suggest that IOP is a heritable trait. More recently, genome-wide association studies (GWAS) have shown that common genetic variants in the GAS7 and TMCO1 genomic regions are associated with elevated IOP. TMCO1 has also been associated with primary open-angle glaucoma in patients with advanced disease. A further study identifying additional genes contributing to IOP will be necessary to fully define the underlying genetic architecture of IOP.
PURPOSE: The rate at which the orbit matures is not well-documented. Limiting this pursuit are the difficulties inherent in measuring orbital volumes accurately. This study compared 3 common methods of determining orbital volume and sought to identify an accurate, practical manner for doing so. METHODS: The volume of 1 orbit of 8 human cadaver heads was independently measured using 3 different methods: 1) CT was performed, and images were analyzed with 3-dimensional (3D) volumetric software; 2) The same orbits were then exenterated and a silicone cast was taken. The cast volumes were measured by water displacement; 3) The orbits were then filled with 1-mm glass beads that were transferred to a graduated cylinder where their volume was determined. The data were analyzed statistically. RESULTS: Intraobserver agreements were good for both beads and casts. Interobserver agreements were good for both beads and CT (p > 0.05). Values obtained using the bead method were equal to values obtained using the cast method (p > 0.05). However, agreement between direct (orbital fillers and casts) and indirect measurements (radiographic techniques) was not satisfactory (p < 0.05). CONCLUSIONS: Independent of method, determining orbital volume is inherently difficult owing to the hyperbolic parabola that is the orbit entrance; all methods require estimation. Glass beads and casts yielded more reproducible values but can only be used in cadavers. CT measurement is prone to error due to the variability of methodologies used but allows access to enormous testing populations. Interstudy comparison is currently not possible. CT volumetric software with strict universal standards for estimating the anterior limit of the orbit appears to be the best method of studying human orbital volumes.
PURPOSE: Immunohistochemical studies have begun to advance knowledge regarding the pathogenesis of vascular anomalies in many anatomical regions. However, the immunohistochemical features of most orbital tumors have been overlooked. Therefore, a comparative immunohistochemical study of a series of the 2 most common orbital vascular lesions- infantile hemangioma (IH) and encapsulated cavernous venous lesion (ECVL), the latter also termed cavernous hemangioma or venous malformation-was undertaken. METHODS: Twenty surgically excised orbital tumors diagnosed clinically and histopathologically as IHs (10 cases) or "cavernous hemangioma" (10 cases) were evaluated pathologically and immunohistochemically using hematoxylin and eosin, Alcian blue, Masson trichrome, GLUT-1, CD31, CD34, D2-40, smooth muscle actin (SMA), desmin, and Ki-67 probes. RESULTS: All cases reacted strongly with the traditional blood vessel endothelial markers CD31 and CD34 and were negative for D2-40, a selective marker for lymphatic endothelium. All IH were positive for GLUT-1, and all ECVL were negative for GLUT-1. In IH, SMA (but not desmin) stained a monolayer of pericytes and in ECVL multilaminar smooth muscle vascular mural cells and intravascular (interstitial) stromal cells. Nuclear Ki-67 immunostaining was strongly positive in IH (average of 16.3%) and close to zero in ECVL. CONCLUSIONS: Immunophenotypic results for ECVL and IH demonstrated no overlapping staining patterns. Infantile hemangioma had the classical architecture of capillaries. Because of the constant presence of mural smooth muscle, it was concluded that ECVL is an accurate and descriptive term. However, desmin negativity in ECVL indicates myofibroblastic differentiation rather than full-fledged smooth muscle differentiation. Infantile hemangioma may display ectatic channels as the lesion ages but does not acquire multilaminar smooth muscle walls. Its pericytes lack cytoplasmic filaments and desmin reactivity but are SMA-positive because of the presence of poorly polymerized actin in the cytosol. In IH, Ki-67 positivity was observed in the endothelial cells of the solid and more ectatic regions. In contrast, the virtual absence of Ki-67 positivity in ECVL lends further support for the interpretation that it is more closely related to a malformation than a benign neoplasm.
PURPOSE: Infants with orbital hemangiomas and vascular malformations often develop expanded orbits or regional hyperostosis. Treatment in these cases depends, in part, on the stage of orbital development at the time of intervention; yet, orbital development with respect to age is not well-known. The authors sought to determine the rate of orbital development and the age of orbital maturation in a single ethnic population. METHODS: Skeletons recovered in North America and housed at the Peabody Museum of Archaeology and Ethnology, Harvard University, were inspected. The age of specimen was determined by dentition. Orbital volume was measured using 1-mm glass beads and a graduated cylinder. Linear measurements were taken with calipers and paper rulers. The measurements were plotted against age, and statistical analysis was performed. Relevant literature was reviewed. RESULTS: Of the hundreds of skeletons examined, 42 were sufficiently intact for orbital measurement. The specimens represented a period of up to 1000 years. Thirty-two were pediatric (defined prenatal to 18 years) and 10 were adults. Mean adult orbital volume was 26.2 ml. Based on the regression analysis, 60% of adult orbital volume was achieved at 4.35 years, 75% at 9.36 years, and 90% at 17.13 years of age. Linear dimensions progressively increased with age. CONCLUSIONS: This largest direct-measure study of pediatric orbital volume suggests that orbital growth continually decelerates from birth until maturity at 22 years. With 50% of orbital growth occurring by 16 months of age, surgeons removing periocular vascular anomalies after that age should consider concurrent skeletal management.