9 research outputs found
Idiopathic vitreomacular traction and macular hole: a comprehensive review of pathophysiology, diagnosis, and treatment
No full textPosterior vitreous detachment (PVD) is a common phenomenon in the aging eye. However, this may be complicated by persistent symptomatic vitreomacular adhesions that exert tractional forces on the macula (vitreomacular traction; VMT). VMT itself may be associated with epiretinal membrane formation and the development of idiopathic macular holes (IMH). Such pathologies may cause visual disturbances, including metamorphopsia, photopsia, blurred vision, and decreased visual acuity, which impact an individual's quality of life. Technologies such as optical coherence tomography allow an increasingly more accurate visualisation of the macular anatomy, including quantification of macular hole characteristics, and this facilitates treatment decision-making. Pars plana vitrectomy remains the primary treatment option for many patients with VMT or IMH; for the latter, peeling of the inner limiting membrane (ILM) of the retina has shown improved outcomes when compared with no ILM peeling. The development of narrow-gauge transconjunctival vitrectomy systems has improved the rate of visual recovery following surgery. Ocriplasmin, by degrading laminin and fibronectin at the vitreoretinal interface, may allow induction of PVD in a non-invasive manner. Indeed, clinical studies have supported its use as an alternative to surgery in certain patient populations. However, further research is still needed with respect to greater understanding of the pathophysiology underlying the development of VMT and IMH
Internal limiting membrane peeling in macular hole surgery; Why, when, and how?
No full textPurpose: To review the current rationale for internal limiting membrane (ILM) peeling in macular hole (MH) surgery and to discuss the evidence base behind why, when, and how surgeons peel the ILM. Methods: Review of the current literature. Results: Pars plana vitrectomy is an effective treatment for idiopathic MH, and peeling of the ILM has been shown to improve closure rates and to prevent postoperative reopening. However, some authors argue against ILM peeling because it results in a number of changes in retinal structure and function and may not be necessary in all cases. Furthermore, the extent of ILM peeling optimally performed and the most favorable techniques to remove the ILM are uncertain. Several technique variations including ILM flaps, ILM scraping, and foveal sparing ILM peeling have been described as alternatives to conventional peeling in specific clinical scenarios. Conclusion: Internal limiting membrane peeling improves MH closure rates but can have several consequences on retinal structure and function. Adjuvants to aid peeling, instrumentation, technique, and experience may all alter the outcome. Hole size and other variables are important in assessing the requirement for peeling and potentially its extent. A variety of evolving alternatives to conventional peeling may improve outcomes and need further study. © 2018 Lippincott Williams and Wilkins. All rights reserved
Real world outcomes of ocriplasmin use by members of the British and Eire Association of Vitreoretinal Surgeons
No full textPurpose:
To describe a survey of the use of ocriplasmin by members of the British and Eire Association of VitreoRetinal Surgeons (BEAVRS) for VitreoMacular Traction (VMT) and Full Thickness Macular Hole (FTMH) and compare it to published MIVI TRUST trial data.
Methods:
All 173 BEAVRS members were contacted by email in October 2014 requesting data on all cases treated with ocriplasmin up to that date. The total number of cases, FTMH closure rate, VMT release rate and the frequency of adverse events were recorded. Results were compared with trial data.
Results:
48 members responded reporting results from 241 eyes. The respective BEAVRS and MIVI TRUST trial closure rates for small FTMHs were 42.1 and 58.3% (P=0.09) and for medium FTMH 12.7 and 36.7% (P=0.01). The respective VMT release rates were 34.1 and 37.4% (P=NS). Retinal detachment was observed in 3.3% of the BEAVRS cohort compared with 0.4% in MIVI TRUST. Reduction in visual acuity to <6/60 was observed in 5.8% of the BEAVRS cohort and 0.6% in MIVI TRUST. Other complications not reported in the MIVI TRUST trial included an increase in FTMH basal diameter following unsuccessful ocriplasmin use in 46.9% of BEAVRS cases and zonular instability at the time of subsequent phacoemulsification in 2.4%.
Conclusion:
Macular hole closure rates were lower in the BEAVRS survey than published in the MIVI TRUST trial data. The incidence of adverse events was greater than previously reported. The reasons for these disparities are unknown but could include positive reporting bias inherent to retrospective surveys, treatment and population differences
The rare C9 P167S risk variant for age-related macular degeneration increases polymerization of the terminal component of the complement cascade
No full textAge-related macular degeneration (AMD) is a complex neurodegenerative eye disease with behavioral and genetic etiology and is the leading cause of irreversible vision loss among elderly Caucasians. Functionally significant genetic variants in the alternative pathway of complement have been strongly linked to disease. More recently, a rare variant in the terminal pathway of complement has been associated with increased risk, Complement component 9 (C9) P167S. To assess the functional consequence of this variant, C9 levels were measured in two independent cohorts of AMD patients. In both cohorts, it was demonstrated that the P167S variant was associated with low C9 plasma levels. Further analysis showed that patients with advanced AMD had elevated sC5b-9 compared to those with non-advanced AMD, although this was not associated with the P167S polymorphism. Electron microscopy of membrane attack complexes (MACs) generated using recombinantly produced wild type or P167S C9 demonstrated identical MAC ring structures. In functional assays, the P167S variant displayed a higher propensity to polymerize and a small increase in its ability to induce hemolysis of sheep erythrocytes when added to C9-depleted serum. The demonstration that this C9 P167S AMD risk polymorphism displays increased polymerization and functional activity provides a rationale for the gene therapy trials of sCD59 to inhibit the terminal pathway of complement in AMD that are underway.</p
Elevational constraints on the composition and genomic attributes of microbial communities in Antarctic soils
No full text© The Author(s), 2022. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Dragone, N. B., Henley, J. B., Holland-Moritz, H., Diaz, M., Hogg, I. D., Lyons, W. B., Wall, D. H., Adams, B. J., & Fierer, N. Elevational constraints on the composition and genomic attributes of microbial communities in Antarctic soils. Msystems, 7(1), (2022): e01330-21, https://doi.org/10.1128/msystems.01330-21.The inland soils found on the Antarctic continent represent one of the more challenging environments for microbial life on Earth. Nevertheless, Antarctic soils harbor unique bacterial and archaeal (prokaryotic) communities able to cope with extremely cold and dry conditions. These communities are not homogeneous, and the taxonomic composition and functional capabilities (genomic attributes) of these communities across environmental gradients remain largely undetermined. We analyzed the prokaryotic communities in soil samples collected from across the Shackleton Glacier region of Antarctica by coupling quantitative PCR, marker gene amplicon sequencing, and shotgun metagenomic sequencing. We found that elevation was the dominant factor explaining differences in the structures of the soil prokaryotic communities, with the drier and saltier soils found at higher elevations harboring less diverse communities and unique assemblages of cooccurring taxa. The higher-elevation soil communities also had lower maximum potential growth rates (as inferred from metagenome-based estimates of codon usage bias) and an overrepresentation of genes associated with trace gas metabolism. Together, these results highlight the utility of assessing community shifts across pronounced environmental gradients to improve our understanding of the microbial diversity found in Antarctic soils and the strategies used by soil microbes to persist at the limits of habitability.Geospatial support for this work was provided by the Polar Geospatial Center under NSF-OPP awards 1043681 and 155969. This work was supported by grants from the U.S. National Science Foundation Office of Polar Programs (1341629, 1341629, 1341736, and 1637708 to B.J.A., N.F., W.B.L., and D.H.W.), with additional support provided to N.B.D. from the University of Colorado Department of Ecology and Evolutionary Biology
Assessment of stereoscopic optic disc images using an autostereoscopic screen - experimental study
No full textBACKGROUND: Stereoscopic assessment of the optic disc morphology is an important part of the care of patients with glaucoma. The aim of this study was to assess stereoviewing of stereoscopic optic disc images using an example of the new technology of autostereoscopic screens compared to the liquid shutter goggles.
METHODS: Independent assessment of glaucomatous disc characteristics and measurement of optic disc and cup parameters whilst using either an autostereoscopic screen or liquid crystal shutter goggles synchronized with a view switching display. The main outcome measures were inter-modality agreements between the two used modalities as evaluated by the weighted kappa test and Bland Altman plots. RESULTS: Inter-modality agreement for measuring optic disc parameters was good [Average kappa coefficient for vertical Cup/Disc ratio was 0.78 (95% CI 0.62-0.91) and 0.81 (95% CI 0.6-0.92) for observer 1 and 2 respectively]. Agreement between modalities for assessing optic disc characteristics for glaucoma on a five-point scale was very good with a kappa value of 0.97.
CONCLUSION: This study compared two different methods of stereo viewing. The results of assessment of the different optic disc and cup parameters were comparable using an example of the newly developing autostereoscopic display technologies as compared to the shutter goggles system used. The Inter-modality agreement was high. This new technology carries potential clinical usability benefits in different areas of ophthalmic practice
Epimacular Brachytherapy for Previously Treated Neovascular Age-Related Macular Degeneration (MERLOT) A Phase 3 Randomized Controlled Trial
No full textPurposeTo assess the safety and efficacy of epimacular brachytherapy (EMB) for patients with chronic, active, neovascular age-related macular degeneration (AMD).DesignPhase 3 randomized controlled trial.ParticipantsPatients (n = 363) with neovascular AMD already receiving intravitreal ranibizumab injections.InterventionEither pars plana vitrectomy with 24-gray EMB and ongoing pro re nata (PRN) ranibizumab (n = 224) or ongoing PRN ranibizumab monotherapy (n = 119).Main Outcome MeasuresThe coprimary outcomes, at 12 months, were the number of PRN ranibizumab injections and Early Treatment of Diabetic Retinopathy Study (ETDRS) best-corrected visual acuity (VA). Secondary outcomes included the proportion of participants losing fewer than 15 ETDRS letters, angiographic total lesion size, choroidal neovascularization (CNV) size, and optical coherence tomography (OCT) foveal thickness. A predefined subgroup analysis tested the influence of baseline ocular characteristics on the response to EMB.ResultsThe mean number of PRN ranibizumab injections was 4.8 in the EMB arm and 4.1 in the ranibizumab monotherapy arm (P = 0.068). The mean VA change was −4.8 letters in the EMB arm and −0.9 letters in the ranibizumab arm (95% confidence interval of difference between groups, −6.6 to −1.8 letters). The proportion of participants losing fewer than 15 letters was 84% in the EMB arm and 92% in the ranibizumab arm (P = 0.007). In the EMB arm, the mean total lesion size increased by 1.2 mm2 versus 0.4 mm2 in the ranibizumab arm (P = 0.27). The CNV size decreased by 0.5 mm2 in the EMB arm and by 1.3 mm2 in the ranibizumab arm (P = 0.27). The OCT foveal thickness decreased by 1.0 μm in the EMB arm and by 15.7 μm in the ranibizumab arm (P = 0.43). Most subgroups favored ranibizumab monotherapy, some significantly so. One participant showed retinal vascular abnormality attributed to radiation, but otherwise safety was acceptable.ConclusionsThese results do not support the use of EMB for chronic, active, neovascular AMD. Safety is acceptable out to 12 months, but radiation retinopathy can occur later, so further follow-up is planned
Stereoscopic 3D Technologies for Accurate Depth Tasks: A Theoretical and Empirical Study
No full textIn the last decade an increasing number of application fields, including medicine, geoscience and bio-chemistry, have expressed a need to visualise and interact with data that are inherently three-dimensional. Stereoscopic 3D technologies can offer a valid support for these operations thanks to the enhanced depth representation they can provide. However, there is still little understanding of how such technologies can be used effectively to support
the performance of visual tasks based on accurate depth judgements. Existing studies do not provide a sound and complete explanation of the impact of different visual and
technical factors on depth perception in stereoscopic 3D environments.
This thesis presents a new interpretative and contextualised analysis of the vision science literature to clarify the role of di®erent visual cues on human depth perception in such environments. The analysis identifies luminance contrast, spatial frequency, colour, blur,
transparency and depth constancies as influential visual factors for depth perception and provides the theoretical foundation for guidelines to support the performance of accurate stereoscopic depth tasks.
A novel assessment framework is proposed and used to conduct an empirical study to evaluate the performance of four distinct classes of 3D display technologies. The results suggest that 3D displays are not interchangeable and that the depth representation provided can vary even between displays belonging to the same class. The study also shows that interleaved displays may suffer from a number of aliasing artifacts, which in turn may affect the amount of perceived depth.
The outcomes of the analysis of the influential visual factors for depth perception and the empirical comparartive study are used to propose a novel universal 3D cursor prototype suitable to support depth-based tasks in stereoscopic 3D environments. The contribution includes a number of both qualitative and quantitative guidelines that aim to guarantee a correct perception of depth in stereoscopic 3D environments and that should be observed
when designing a stereoscopic 3D cursor
Reduced glutathione and cysteine hydrochloride on crossbred bull semen
No full textOver the last few years, good quality freezable semen was not utilized effectively due to less knowledge about the freezability of semen. One reason is the lack of sufficient antioxidants in the seminal plasma and semen extender. The antioxidant content is reduced during the cryopreservation process and causes premature cryo-capacitation and modification of sperm membrane structure upon thawing. So the study of pre-freezing and post thaw seminal parameters like viability, motility, acrosomal integrity, lipid peroxide assay, vanguard distance traveled by sperm, mitochondrial membrane potential, velocity and motility parameters (CASA) and field fertility trial helped to assess the effectiveness of the additives. The conception rate was better in reduced glutathione than the cysteine hydrochloride treated group. The glutathione has improved the poor freezing and maintained the good freezable semen. Thus the field fertility rate was enhanced and in turn helped to prevent waste of good quality germplasm and repeat breeder syndrome in cows
