March 2013

Argüeso P. Glycobiology of the ocular surface: mucins and lectins. Jpn J Ophthalmol 2013;57(2):150-5.Abstract
Glycosylation is an important and common form of posttranscriptional modification of proteins in cells. During the last decade, a vast array of biological functions has been ascribed to glycans because of a rapid evolution in glycomic technologies. Glycogenes that are highly expressed at the human ocular surface include families of glycosyltransferases, proteoglycans, and glycan degradation proteins, as well as mucins and carbohydrate-binding proteins, such as the galectins. On the apical glycocalyx, mucin O-glycans promote boundary lubrication, prevent bacterial adhesion and endocytic activity, and maintain epithelial barrier function through interactions with galectins. The emerging roles attributed to glycans are contributing to the appreciation of their biological capabilities at the ocular surface.
Cepko CL, Vandenberghe LH. Retinal gene therapy coming of age. Hum Gene Ther 2013;24(3):242-4.
Connors EC, Yazzolino LA, Sánchez J, Merabet LB. Development of an audio-based virtual gaming environment to assist with navigation skills in the blind. J Vis Exp 2013;(73)Abstract
Audio-based Environment Simulator (AbES) is virtual environment software designed to improve real world navigation skills in the blind. Using only audio based cues and set within the context of a video game metaphor, users gather relevant spatial information regarding a building's layout. This allows the user to develop an accurate spatial cognitive map of a large-scale three-dimensional space that can be manipulated for the purposes of a real indoor navigation task. After game play, participants are then assessed on their ability to navigate within the target physical building represented in the game. Preliminary results suggest that early blind users were able to acquire relevant information regarding the spatial layout of a previously unfamiliar building as indexed by their performance on a series of navigation tasks. These tasks included path finding through the virtual and physical building, as well as a series of drop off tasks. We find that the immersive and highly interactive nature of the AbES software appears to greatly engage the blind user to actively explore the virtual environment. Applications of this approach may extend to larger populations of visually impaired individuals.
De Castro DK, Fay A, Wladis EJ, Nguyen J, Osaki T, Metson R, Curry W. Self-irrigating piezoelectric device in orbital surgery. Ophthalmic Plast Reconstr Surg 2013;29(2):118-22.Abstract
PURPOSE: Orbital osteotomy risks injury to the eyeball and orbit soft tissues. Used extensively in oral and maxillofacial surgery, piezoelectric technology offers a greater margin of safety than traditional bone cutting instruments. The authors describe the novel use of this system in a variety of orbital surgeries. METHODS: This interventional case series was performed in accordance with institutional review board regulations. The medical records of all patients who had undergone orbital surgery using the piezoelectric blade at 3 institutions were reviewed. Indication for surgery, gender, age, duration of follow up, intraoperative complications, surgical result, and postoperative course was recorded. RESULTS: Sixteen patients underwent surgery on 18 orbits using the piezoelectric system between August 2011 and June 2012. Surgeries performed included orbital decompression (8), lateral orbitotomy (5), cranio-orbitotomy (4), and external dacryocystorhinostomy (1). Eight were female and 8 were male patients. Mean age was 55 years old (standard deviation 15 years). Mean follow up was 82 days. The osteotomy created by the blade was narrow and smooth in every case. The surgeons uniformly appreciated the precision and safety of the instrument compared with traditional electric saw blades. There were no soft tissue lacerations or intraoperative complications and reconstructions were uniformly uneventful. Postoperative healing was rapid with no unexpected inflammation, and no palpable bony defects were appreciated in the reconstructed cases. CONCLUSIONS: Because it does not cut soft tissue and cuts a narrow trough, the self-irrigating piezoelectric saw blade appears safer and more precise than traditional electric saw blades in and around the orbit.
Hagstrom SA, Ying G-S, Pauer GJT, Sturgill-Short GM, Huang J, Callanan DG, Kim IK, Klein ML, Maguire MG, Martin DF, of Group CAMDTTR. Pharmacogenetics for genes associated with age-related macular degeneration in the Comparison of AMD Treatments Trials (CATT). Ophthalmology 2013;120(3):593-599.Abstract
PURPOSE: To evaluate the pharmacogenetic relationship between genotypes of single nucleotide polymorphisms (SNPs) known to be associated with age-related macular degeneration (AMD) and response to treatment with ranibizumab (Lucentis; Genentech, South San Francisco, CA) or bevacizumab (Avastin; Genentech) for neovascular AMD. DESIGN: Clinical trial. PARTICIPANTS: Eight hundred thirty-four (73%) of 1149 patients participating in the Comparison of AMD Treatments Trials (CATT) were recruited through 43 CATT clinical centers. METHODS: Each patient was genotyped for SNPs rs1061170 (CFH), rs10490924 (ARMS2), rs11200638 (HTRA1), and rs2230199 (C3), using TaqMan SNP genotyping assays (Applied Biosystems, Foster City, CA). MAIN OUTCOMES MEASURES: Genotypic frequencies were compared with clinical measures of response to therapy at one year, including mean visual acuity (VA), mean change in VA, 15-letter or more increase in VA, retinal thickness, mean change in total foveal thickness, presence of fluid on OCT, presence of leakage on fluorescein angiography (FA), mean change in lesion size, and mean number of injections administered. Differences in response by genotype were evaluated with tests of linear trend calculated from logistic regression models for categorical outcomes and linear regression models for continuous outcomes. To adjust for multiple comparisons, P≤0.01 was considered statistically significant. RESULTS: No statistically significant differences in response by genotype were identified for any of the clinical measures studied. Specifically, there were no high-risk alleles that predicted final VA or change in VA, the degree of anatomic response (fluid on OCT or FA, retinal thickness, change in total foveal thickness, change in lesion size), or the number of injections. Furthermore, a stepwise analysis failed to show a significant epistatic interaction among the variants analyzed; that is, response did not vary by the number of risk alleles present. The lack of association was similar whether patients were treated with ranibizumab or bevacizumab or whether they received monthly or pro re nata dosing. CONCLUSIONS: Although specific alleles for CFH, ARMS2, HTRA1, and C3 may predict the development of AMD, they did not predict response to anti-vascular endothelial growth factor therapy.
Hong J, Xu J, Hua J, Sun X. Bacterial keratitis in Shanghai. Ophthalmology 2013;120(3):647.
Jakobiec FA, Zakka FR, Yoon MK. Complex orbital angiomyoma with features of a lymphangiohemangioma. Ophthalmic Plast Reconstr Surg 2013;29(2):e61-5.Abstract
A 31-year-old woman developed left frontal headache and retrobulbar pain with exotropia and mild limitation of upgaze without proptosis. Imaging studies disclosed a circumscribed mass measuring 1.5 cm in the greatest diameter. At surgery, the lesion was adherent to the surrounding normal orbital tissues, making for a difficult and dangerous resection. Histopathologically and immunohistochemically, the lesion was a mixed cavernous angiomatous (CD31-positive) and lymphangiomatous (D2-40-positive) tumor with abundant interstitial smooth muscle. Such lesions can present significant surgical challenges due to incomplete pseudoencapsulation.
Menon BB, Govindarajan B. Identification of an atypical zinc metalloproteinase, ZmpC, from an epidemic conjunctivitis-causing strain of Streptococcus pneumoniae. Microb Pathog 2013;56:40-6.Abstract
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.
Osaki TH, Fay A, Mehta M, Nallasamy N, Waner M, De Castro DK. Orbital development as a function of age in indigenous North American skeletons. Ophthalmic Plast Reconstr Surg 2013;29(2):131-6.Abstract
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.
Palioura S, Chodosh J, Pineda R. A novel approach to the management of a progressive Descemet membrane tear in a patient with keratoglobus and acute hydrops. Cornea 2013;32(3):355-8.Abstract
PURPOSE: To report a case of corneal hydrops in a patient with keratoglobus that was managed with endothelial keratoplasty to achieve corneal stability and prevent a limbus-to-limbus tear in Descemet membrane. METHODS: A 30-year-old man with keratoglobus presented with corneal hydrops in his left eye resulting from a central vertical tear in Descemet membrane. His other eye had been previously treated with penetrating keratoplasty using a large graft (an 11-mm donor graft to a 10-mm recipient bed) because of a limbus-to-limbus tear in Descemet membrane without resolution of his edema. An attempt to approximate the edges of the Descemet tear in the left eye by an intracameral air injection failed, and the tear continued to progress peripherally. An endothelial keratoplasty button with anchoring sutures was placed over the Descemet tear because of excessive localized edema. RESULTS: One month after insertion of the sutured endothelial keratoplasty button, the edema had resolved, and 1 year later, the tear remains sealed. The patient's visual acuity improved from counting fingers at 1 foot to 20/100. CONCLUSIONS: Reconstitution of the posterior corneal surface in keratoglobus-induced hydrops can be achieved with endothelial keratoplasty over the Descemet tear. Preventing progression of a central Descemet tear is essential to bypass the need for a large-diameter penetrating keratoplasty graft and its complications in a young patient with a history of bilateral corneal hydrops.
Poole Perry LJ, Jakobiec FA, Zakka FR, Reichel E, Herwig MC, Perry A, Brat DJ, Grossniklaus HE. Reactive retinal astrocytic tumors (so-called vasoproliferative tumors): histopathologic, immunohistochemical, and genetic studies of four cases. Am J Ophthalmol 2013;155(3):593-608.e1.Abstract
PURPOSE: To evaluate the cellular nature of and diagnostic terminology used in connection with acquired retinal "vasoproliferative tumors." DESIGN: Retrospective clinicopathologic study. METHODS: Clinical records and microscopic slides of 4 enucleated globes were reviewed. Special stains and immunohistochemical probes for CD31, CD34, p53, glial fibrillary acidic protein (GFAP), CD163, and Ki67 (cell replication) were employed; ultrastructural and fluorescence in situ hybridization (FISH) analyses were performed. RESULTS: Tumors were located inferotemporally in middle-aged patients. They were uniformly composed of compacted elongated, GFAP-positive spindle cells (due to intermediate filaments identified ultrastructurally) with a Ki67 index of less than 1%. Rosenthal fibers and eosinophilic granular bodies were observed. Hyalinized periodic acid-Schiff-positive vessels were widely separated. CD31 and CD34 revealed a sparse microvasculature. Tumor-associated exudate spread predominantly subretinally. The retinal pigment epithelium had undergone extensive placoid fibrous metaplasia with focal ossification. P53 upregulation, BRAF-KIAA gene rearrangement, and IDH1R132H mutation typically associated with low-grade astrocytic neoplasms were absent. CONCLUSIONS: Retinal "vasoproliferative" tumors have been mischaracterized, because they actually display a paucity of microvessels. Proliferating fibrous astrocytes with a very low proliferation index predominate, without immunohistochemical or genetic evidence favoring a neoplasm. Subretinal exudate appeared capable of provoking widespread fibrous metaplasia of the pigment epithelium that was mainly responsible for secondary retinal damage. The term "reactive retinal astrocytic tumor" is proposed as more appropriate for this entity. In carefully selected progressive lesions, consideration should be given to earlier surgical intervention before extensive subretinal exudate accumulates and pigment epithelial proliferation with fibrous metaplasia ensues.
Stryjewski TP, Vavvas DG. Genetic correlates of proliferative vitreoretinopathy. Invest Ophthalmol Vis Sci 2013;54(3)
Swaminathan SS, Oh D-J, Kang MH, Ren R, Jin R, Gong H, Rhee DJ. Secreted protein acidic and rich in cysteine (SPARC)-null mice exhibit more uniform outflow. Invest Ophthalmol Vis Sci 2013;54(3):2035-47.Abstract
PURPOSE: Secreted protein acidic and rich in cysteine (SPARC) is a matricellular protein known to regulate extracellular matrix (ECM) in many tissues and is highly expressed in trabecular meshwork (TM). SPARC-null mice have a 15% to 20% decrease in intraocular pressure (IOP) compared to wild-type (WT) mice. We hypothesized that mouse aqueous outflow is segmental, and that transgenic deletion of SPARC causes a more uniform pattern that correlates with IOP and TM morphology. METHODS: Eyes of C57BL6-SV129 WT and SPARC-null mice were injected with fluorescent microbeads, which were also passively exposed to freshly enucleated eyes. Confocal and electron microscopy were performed. Percentage effective filtration length (PEFL) was calculated as PEFL = FL/TL × 100%, where TL = total length and FL = filtration length. IOP was measured by rebound tonometry. RESULTS: Passive microbead affinity for WT and SPARC-null ECM did not differ. Segmental flow was observed in the mouse eye. SPARC-null mice had a 23% decrease in IOP. PEFL increased in SPARC-null (70.61 ± 11.36%) versus WT mice (54.68 ± 9.95%, P < 0.005; n = 11 pairs), and PEFL and IOP were negatively correlated (R(2) = 0.72, n = 10 pairs). Morphologically, TM of high-tracer regions had increased separation between beams compared to low-tracer regions. Collagen fibril diameter decreased in SPARC-null (28.272 nm) versus WT tissue (34.961 nm, P < 0.0005; n = 3 pairs). CONCLUSIONS: Aqueous outflow in mice is segmental. SPARC-null mice demonstrated a more uniform outflow pattern and decreased collagen fibril diameter. Areas of high flow had less compact juxtacanalicular connective tissue ECM, and IOP was inversely correlated with PEFL. Our data show a correlation between morphology, aqueous outflow, and IOP, indicating a modulatory role of SPARC in IOP regulation.
Vavvas DG. Anti-VEGF in retinopathy of prematurity, need to titrate. Invest Ophthalmol Vis Sci 2013;54(3)
Yonekawa Y, Shildkrot Y, Eliott D. Inferior peripheral nonperfusion in bilateral diffuse uveal melanocytic proliferation. Ophthalmic Surg Lasers Imaging Retina 2013;44(2):190-2.Abstract
Bilateral diffuse uveal melanocytic proliferation (BDUMP) is a paraneoplastic syndrome characterized by cataract, photoreceptor loss and subretinal fluid overlying patchy areas of retinal pigment epithelium atrophy, and a diffusely thickened choroid with focal nodules. We present the case of a 64-year-old woman with a history of endometrial adenocarcinoma who developed BDUMP with bilateral exudative retinal detachments with inferior peripheral retinal ischemia. This new finding of peripheral nonperfusion expands the spectrum of BDUMP.