All

Wen G, Aizenman A, Drew T, Wolfe JM, Haygood TM, Markey MK. Computational assessment of visual search strategies in volumetric medical images. J Med Imaging (Bellingham) 2016;3(1):015501.Abstract

When searching through volumetric images [e.g., computed tomography (CT)], radiologists appear to use two different search strategies: "drilling" (restrict eye movements to a small region of the image while quickly scrolling through slices), or "scanning" (search over large areas at a given depth before moving on to the next slice). To computationally identify the type of image information that is used in these two strategies, 23 naïve observers were instructed with either "drilling" or "scanning" when searching for target T's in 20 volumes of faux lung CTs. We computed saliency maps using both classical two-dimensional (2-D) saliency, and a three-dimensional (3-D) dynamic saliency that captures the characteristics of scrolling through slices. Comparing observers' gaze distributions with the saliency maps showed that search strategy alters the type of saliency that attracts fixations. Drillers' fixations aligned better with dynamic saliency and scanners with 2-D saliency. The computed saliency was greater for detected targets than for missed targets. Similar results were observed in data from 19 radiologists who searched five stacks of clinical chest CTs for lung nodules. Dynamic saliency may be superior to the 2-D saliency for detecting targets embedded in volumetric images, and thus "drilling" may be more efficient than "scanning."

Whitman MC, Andrews C, Chan W-M, Tischfield MA, Stasheff SF, Brancati F, Ortiz-Gonzalez X, Nuovo S, Garaci F, MacKinnon SE, Hunter DG, Grant EP, Engle EC. Two unique TUBB3 mutations cause both CFEOM3 and malformations of cortical development. Am J Med Genet A 2016;170(2):297-305.Abstract

One set of missense mutations in the neuron specific beta tubulin isotype 3 (TUBB3) has been reported to cause malformations of cortical development (MCD), while a second set has been reported to cause isolated or syndromic Congenital Fibrosis of the Extraocular Muscles type 3 (CFEOM3). Because TUBB3 mutations reported to cause CFEOM had not been associated with cortical malformations, while mutations reported to cause MCD had not been associated with CFEOM or other forms of paralytic strabismus, it was hypothesized that each set of mutations might alter microtubule function differently. Here, however, we report two novel de novo heterozygous TUBB3 amino acid substitutions, G71R and G98S, in four patients with both MCD and syndromic CFEOM3. These patients present with moderately severe CFEOM3, nystagmus, torticollis, and developmental delay, and have intellectual and social disabilities. Neuroimaging reveals defective cortical gyration, as well as hypoplasia or agenesis of the corpus callosum and anterior commissure, malformations of hippocampi, thalami, basal ganglia and cerebella, and brainstem and cranial nerve hypoplasia. These new TUBB3 substitutions meld the two previously distinct TUBB3-associated phenotypes, and implicate similar microtubule dysfunction underlying both. © 2015 Wiley Periodicals, Inc.

Sparrow JR, Duncker T, Woods R, Delori FC. Quantitative Fundus Autofluorescence in Best Vitelliform Macular Dystrophy: RPE Lipofuscin is not Increased in Non-Lesion Areas of Retina. Adv Exp Med Biol 2016;854:285-90.Abstract

Since the lipofuscin of retinal pigment epithelial (RPE) cells has been implicated in the pathogenesis of Best vitelliform macular dystrophy, we quantified fundus autofluorescence (quantitative fundus autofluorescence, qAF) as an indirect measure of RPE lipofuscin levels. Mean non-lesion qAF was found to be within normal limits for age. By spectral domain optical coherence tomography (SD-OCT) vitelliform lesions presented as fluid-filled subretinal detachments containing reflective material. We discuss photoreceptor outer segment debris as the source of the intense fluorescence of these lesions and loss of anion channel functioning as an explanation for the bullous photoreceptor-RPE detachment. Unexplained is the propensity of the disease for central retina.

Fernandez-Godino R, Pierce EA, Garland DL. Extracellular Matrix Alterations and Deposit Formation in AMD. Adv Exp Med Biol 2016;854:53-8.Abstract

Age related macular degeneration (AMD) is the primary cause of vision loss in the western world (Friedman et al., Arch Ophthalmol 122:564-572, 2004). The first clinical indication of AMD is the presence of drusen. However, with age and prior to the formation of drusen, extracellular basal deposits accumulate between the retinal pigment epithelium (RPE) and Bruch's membrane (BrM). Many studies on the molecular composition of the basal deposits and drusen have demonstrated the presence of extracellular matrix (ECM) proteins, complement components and cellular debris. The evidence reviewed here suggests that alteration in RPE cell function might be the primary cause for the accumulation of ECM and cellular debri found in basal deposits. Further studies are obviously needed in order to unravel the specific pathways that lead to abnormal formation of ECM and complement activation.

Maleki A, Swan RT, Silpa-Archa S, Preble JM, He Y, Foster SC. Short-Wavelength Automated Perimetry Parameters at Baseline and Following Remission in Patients With Birdshot Retinochoroidopathy. Am J Ophthalmol 2016;163:83-92.e6.Abstract

PURPOSE: To identify changes in short-wavelength automated perimetry patterns and parameters between the active and inactive states. DESIGN: Retrospective cohort study with age-matched, normal controls. METHODS: setting: Private tertiary referral center. STUDY POPULATION: Seventy-five eyes of 38 patients with active birdshot retinochoroidopathy and 37 eyes of 37 historical normal controls. INTERVENTION: Thirty-seven patients received immunomodulatory therapy. A fluocinolone acetonide intravitreal implant (Retisert) was implanted in both eyes of 1 patient as an initial treatment. MAIN OUTCOME MEASURES: Changes in short-wavelength automated perimetry total deviation scores, pattern deviation scores, mean deviation, and pattern standard deviation in the active phase and the remission state. RESULTS: Mean deviation (P = .006), pattern standard deviation (P = .001), total deviation score (P = .002), and pattern deviation score (P = .007) were significantly different from the active phase to the remission state. The length of time required to achieve remission did not significantly affect the changes in mean deviation (regression coefficient = 0.01; P = .92), pattern standard deviation (regression coefficient = 0.01; P = .87), total deviation score (regression coefficient = -0.1; P = .32), or pattern deviation score (regression coefficient = 0.1; P = .36) from the active phase to the remission state. CONCLUSION: There was significant improvement in total deviation score, pattern deviation score, mean deviation, and pattern standard deviation on short-wavelength automated perimetry as patients achieved remission. Short-wavelength automated perimetry appears to be a useful and complementary modality in monitoring disease activity in birdshot retinochoroidopathy.

Pasquale LR, Borrás T, Fingert JH, Wiggs JL, Ritch R. Exfoliation syndrome: assembling the puzzle pieces. Acta Ophthalmol 2016;94(6):e505-12.Abstract

PURPOSE: To summarize various topics and the cutting edge approaches to refine XFS pathogenesis that were discussed at the 21st annual Glaucoma Foundation Think Tank meeting in New York City, Sept. 19-20, 2014. METHODS: The highlights of three categories of talks on cutting edge research in the field were summarized. RESULTS: Exfoliation syndrome (XFS) is a systemic disorder with a substantial ocular burden, including high rates of cataract, cataract surgery complications, glaucoma and retinal vein occlusion. New information about XFS is akin to puzzle pieces that do not quite join together to reveal a clear picture regarding how exfoliation material (XFM) forms. CONCLUSION: Meeting participants concluded that it is unclear how the mild homocysteinemia seen in XFS might contribute to the disarrayed extracellular aggregates characteristic of this syndrome. Lysyl oxidase-like 1 (LOXL1) variants are unequivocally genetic risk factors for XFS but exactly how these variants contribute to the assembly of exfoliation material (XFM) remains unclear. Variants in a new genomic region, CACNA1A associated with XFS, may alter calcium concentrations at the cell surface and facilitate XFM formation but much more work is needed before we can place this new finding in proper context. It is hoped that various animal model and ex vivo systems will emerge that will allow for proper assembly of the puzzle pieces into a coherent picture of XFS pathogenesis. A clear understanding of XFS pathogenesis may lead to 'upstream solutions' to reduce the ocular morbidity produced by XFS.

Xiong W, Cepko C. Distinct Expression Patterns of AAV8 Vectors with Broadly Active Promoters from Subretinal Injections of Neonatal Mouse Eyes at Two Different Ages. Adv Exp Med Biol 2016;854:501-7.Abstract

The retinal expression patterns were analyzed following the injection of serotype 8 adeno-associated virus (AAV8) vectors that utilize two broadly active and commonly used sets of transcription regulatory sequences. These include the human cytomegalovirus (CMV) immediate early (IE) enhancer/promoter and the hybrid CAG element (also known as CAGGS or CBA) composed of a partial human CMV IE enhancer and the chicken β-actin promoter and intron. Subretinal delivery to postnatal day 0 (P0) or 6 (P6) mouse eyes resulted in efficient labeling of retinal cells, but with very distinct patterns. With P0 delivery, AAV8-CMV-GFP selectively labelled photoreceptors, while AAV8-CAG-GFP efficiently labeled both outer and inner retinal neurons, including photoreceptors, horizontal cells, amacrine cells and retinal ganglion cells. With P6 delivery, both vectors led to efficient labeling of photoreceptors and Müller glia cells, but not of inner retinal neurons. Our results suggest that the cell types that express the genes encoded by subretinally delivered AAV8 vectors are determined by both the timing of the injection and the regulatory sequences.

Lienert JP, Tarko L, Uchino M, Christen WG, Schaumberg DA. Long-term Natural History of Dry Eye Disease from the Patient's Perspective. Ophthalmology 2016;123(2):425-33.Abstract

PURPOSE: To describe the natural history of dry eye disease (DED), which chronically affects millions of people in the United States. DESIGN: This study is based on the Women's Health Study and Physicians' Health Studies, and uses questionnaires and medical records. PARTICIPANTS: A total of 398 men and 386 women who reported a diagnosis of DED and responded to a questionnaire about change in disease since diagnosis. METHODS: Three subscales were developed using factor analysis of questionnaire responses: ocular surface symptoms, vision-related symptoms, and social impact. We examined correlates of worsening on each subscale, obtained medical records from a subset of 261 study participants, and examined changes in clinical signs of DED over time. MAIN OUTCOME MEASURES: Worsening in ocular surface symptoms, vision-related symptoms, and social impact plus clinical signs. RESULTS: The average duration of DED of 10.5 years (standard deviation, 9.5 years). Worsening was reported by 24% for ocular surface symptoms, 29% for vision-related symptoms, and 10% for social impact. Factors associated with worsening on at least 2 of 3 subscales included a previous report of severe DED symptoms (odds ratio [OR], 2.17 for ocular surface symptoms; OR, 2.35 for vision-related symptoms), spending >$20 per month on DED treatments (OR, 1.80 for ocular surface symptoms; OR, 1.99 for vision-related symptoms), history of blepharitis or meibomian gland dysfunction (MGD) (OR, 1.57 for vision-related symptoms; OR, 2.12 for social impact), and use of systemic beta-blockers (OR, 1.62 for ocular surface symptoms; OR, 1.84 for vision-related symptoms; OR, 1.86 for the social impact of DED). Presence of corneal staining based on review of medical records was associated with use of level 2 or higher DED treatments (OR, 1.54; confidence interval [CI], 1.01-2.36), a previous report of severe DED symptoms (OR, 1.79; CI, 1.07-3.00), having a tear break-up test performed (OR, 2.73; CI, 1.72-4.36), and having blepharitis or MGD (OR, 0.59; CI, 0.35-0.98). CONCLUSIONS: A proportion of patients with DED experience worsening over time, tending to report with more severe symptoms earlier in the disease. Forthcoming data on the natural history of DED from prospective studies should help clarify some of the limitations of this retrospective study.

Kim C, Smith KE, Castillejos A, Diaz-Aguilar D, Saint-Geniez M, Connor KM. The alternative complement pathway aids in vascular regression during the early stages of a murine model of proliferative retinopathy. FASEB J 2016;30(3):1300-5.Abstract

Proliferative retinopathic diseases often progress in 2 phases: initial regression of retinal vasculature (phase 1) followed by subsequent neovascularization (NV) (phase 2). The immune system has been shown to aid in vascular pruning in such retinopathies; however, little is known about the role of the alternative complement pathway in the initial vascular regression phase. Using a mouse model of oxygen-induced retinopathy (OIR), we observed that alternative complement pathway-deficient mice (Fb(-/-)) exhibited a mild decrease in vascular loss at postnatal day (P)8 compared with age- and strain-matched controls (P = 0.035). Laser capture microdissection was used to isolate the retinal blood vessels. Expression of the complement inhibitors Cd55 and Cd59 was significantly decreased in blood vessels isolated from hyperoxic retinas compared with those from normoxic control mice. Vegf expression was measured at P8 and found to be significantly lower in OIR mice than in normoxic control mice (P = 0.0048). Further examination of specific Vegf isoform expression revealed a significant decrease in Vegf120 (P = 0.00032) and Vegf188 (P = 0.0092). In conjunction with the major modulating effects of Vegf during early retinal vascular development, our data suggest a modest involvement of the alternative complement pathway in targeting vessels for regression in the initial vaso-obliteration stage of OIR.-Kim, C., Smith, K. E., Castillejos, A., Diaz-Aguilar, D., Saint-Geniez, M., Connor, K. M. The alternative complement pathway aids in vascular regression during the early stages of a murine model of proliferative retinopathy.

Carvalho LS, Vandenberghe LH. Understanding Cone Photoreceptor Cell Death in Achromatopsia. Adv Exp Med Biol 2016;854:231-6.Abstract

Colour vision is only achieved in the presence of healthy and functional cone photoreceptors found in the retina. It is an essential component of human vision and usually the first complaint patients undergoing vision degeneration have is the loss of daylight colour vision. Therefore, an understanding of the biology and basic mechanisms behind cone death under the degenerative state of retinal dystrophies and how the activation of the apoptotic pathway is triggered will provide valuable knowledge. It will also have broader applications for a spectrum of visual disorders and will be critical for future advances in translational research.

Grishchuk Y, Stember KG, Matsunaga A, Olivares AM, Cruz NM, King VE, Humphrey DM, Wang SL, Muzikansky A, Betensky RA, Thoreson WB, Haider N, Slaugenhaupt SA. Retinal Dystrophy and Optic Nerve Pathology in the Mouse Model of Mucolipidosis IV. Am J Pathol 2016;186(1):199-209.Abstract

Mucolipidosis IV is a debilitating developmental lysosomal storage disorder characterized by severe neuromotor retardation and progressive loss of vision, leading to blindness by the second decade of life. Mucolipidosis IV is caused by loss-of-function mutations in the MCOLN1 gene, which encodes the transient receptor potential channel protein mucolipin-1. Ophthalmic pathology in patients includes corneal haze and progressive retinal and optic nerve atrophy. Herein, we report ocular pathology in Mcoln1(-/-) mouse, a good phenotypic model of the disease. Early, but non-progressive, thinning of the photoreceptor layer, reduced levels of rhodopsin, disrupted rod outer segments, and widespread accumulation of the typical storage inclusion bodies were the major histological findings in the Mcoln1(-/-) retina. Electroretinograms showed significantly decreased functional response (scotopic a- and b-wave amplitudes) in the Mcoln1(-/-) mice. At the ultrastructural level, we observed formation of axonal spheroids and decreased density of axons in the optic nerve of the aged (6-month-old) Mcoln1(-/-) mice, which indicates progressive axonal degeneration. Our data suggest that mucolipin-1 plays a role in postnatal development of photoreceptors and provides a set of outcome measures that can be used for ocular therapy development for mucolipidosis IV.

Castle MJ, Turunen HT, Vandenberghe LH, Wolfe JH. Controlling AAV Tropism in the Nervous System with Natural and Engineered Capsids. Methods Mol Biol 2016;1382:133-49.Abstract

More than one hundred naturally occurring variants of adeno-associated virus (AAV) have been identified, and this library has been further expanded by an array of techniques for modification of the viral capsid. AAV capsid variants possess unique antigenic profiles and demonstrate distinct cellular tropisms driven by differences in receptor binding. AAV capsids can be chemically modified to alter tropism, can be produced as hybrid vectors that combine the properties of multiple serotypes, and can carry peptide insertions that introduce novel receptor-binding activity. Furthermore, directed evolution of shuffled genome libraries can identify engineered variants with unique properties, and rational modification of the viral capsid can alter tropism, reduce blockage by neutralizing antibodies, or enhance transduction efficiency. This large number of AAV variants and engineered capsids provides a varied toolkit for gene delivery to the CNS and retina, with specialized vectors available for many applications, but selecting a capsid variant from the array of available vectors can be difficult. This chapter describes the unique properties of a range of AAV variants and engineered capsids, and provides a guide for selecting the appropriate vector for specific applications in the CNS and retina.

Taub DG, Liu Q. The Role of Intraflagellar Transport in the Photoreceptor Sensory Cilium. Adv Exp Med Biol 2016;854:627-33.Abstract

The photoreceptor is a complex specialized cell in which a major component responsible for visual transduction is the photoreceptor sensory cilium (PSC). Building and maintenance of the PSC requires the transport of large proteins along microtubules that extend from the inner segments to the outer segments. A key process, termed intraflagellar transport (IFT), has been recognized as an essential phenomenon for photoreceptor development and maintenance, and exciting new studies have highlighted its importance in retinal and cilia related diseases. This review focuses on the important roles of IFT players, including motor proteins, IFT proteins, and photoreceptor-specific cargos in photoreceptor sensory cilium. In addition, specific IFT components that are involved in inherited human diseases are discussed.

Kheirkhah A, Saboo US, Marmalidou A, Dana R. Overestimation of Corneal Endothelial Cell Density in Smaller Frame Sizes in In Vivo Confocal Microscopy. Cornea 2016;35(3):363-9.Abstract

PURPOSE: To evaluate the effect of frame size on the calculated corneal endothelial cell density (CECD) in images of laser scanning in vivo confocal microscopy (IVCM). METHODS: Forty-nine corneal endothelial images acquired by laser scanning IVCM (Heidelberg Retina Tomograph 3 with Rostock Corneal Module) with different endothelial cell densities were analyzed. In each image (160,000 μm), the CECD was calculated using the fixed-frame method by counting cells in the following frame sizes: 80,000 μm, 40,000 μm, 20,000 μm, 10,000 μm, 5000 μm, and 2500 μm. The calculated CECD was then compared with that of the variable-frame method as the reference value. RESULTS: There was no significant difference in the calculated CECD between the variable-frame method (2004 ± 832 cells/mm), and the fixed-frame method using a 40,000-μm frame (2023 ± 810 cells/mm). On the other hand, the calculated CECD showed significant overestimations in frame sizes of 20,000 μm (2066 ± 820 cells/mm), 10,000 μm (2156 ± 785 cells/mm), 5000 μm (2352 ± 783 cells/mm), and 2500 μm (2715 ± 754 cells/mm), with P < 0.001 in all. This resulted in overestimations of 4.8 ± 9.8%, 11.9 ± 16.2%, 24.9 ± 23.1%, and 49.1 ± 38.8% for these frame sizes, respectively. Images with lower CECD demonstrated higher overestimations of cell density in smaller frame sizes. CONCLUSIONS: In laser scanning IVCM images, there is significant overestimation of CECD if the cells are counted in frames smaller than 25% of the image. Similar frame sizes should be used when monitoring CECD over time.

Pages