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J Sebag - One of the best experts on this subject based on the ideXlab platform.
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Assessment of Vitreous Structure and Visual Function after Neodymium:Yttrium-Aluminum-Garnet Laser Vitreolysis.
Ophthalmology, 2019Co-Authors: Justin Nguyen, Kenneth M P Yee, Jeannie Nguyen-cuu, Jonathan Mamou, Ronald H. Silverman, Jeffrey A. Ketterling, J SebagAbstract:Purpose Neodymium:yttrium–aluminum–garnet (Nd:YAG) laser treatment is performed on Vitreous floaters, but studies of structural and functional effects with objective outcome measures are lacking. This study evaluated Nd:YAG laser effects by comparing participants with Vitreous floaters who previously underwent laser treatment with untreated control participants and healthy persons without Vitreous floaters using quantitative ultrasonography to evaluate Vitreous structure and by measuring visual acuity and contrast sensitivity function to assess vision. Design Retrospective, comparative study. Participants One eye was enrolled for each of 132 participants: 35 control participants without Vitreous floaters, 59 participants with untreated Vitreous floaters, and 38 participants with Vitreous floaters previously Nd:YAG-treated. Of these, 25 were dissatisfied and sought vitrectomy; 13 were satisfied with observation. Methods The 39-item National Eye Institute Visual Function Questionnaire (NEI-VFQ-39) to assess participant visual well-being, quantitative ultrasonography (QUS) to measure Vitreous echodensity, and best-corrected visual acuity (BCVA) and contrast sensitivity function (CSF) to evaluate vision. Main Outcome Measures Results of NEI-VFQ-39, QUS, BCVA, and CSF. Results Compared with control participants without Vitreous floaters, participants with untreated Vitreous floaters showed worse NEI-VFQ-39 results, 57% greater Vitreous echodensity, and significant (130%) CSF degradation (P Conclusions As a group, participants previously treated with Nd:YAG laser for bothersome Vitreous floaters showed less dense Vitreous, but similar visual function as untreated control participants with Vitreous floaters. Because some treated eyes showed less dense Vitreous and better visual function than those of untreated control participants, a prospective randomized study of Nd:YAG laser treatment of Vitreous is warranted, using uniform laser treatment parameters and objective quantitative outcome measures.
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Vitreous: the resplendent enigma
The British journal of ophthalmology, 2009Co-Authors: J SebagAbstract:Arguably the most enigmatic of ocular structures, Vitreous has long been unappreciated with respect to its role in health and disease. The classic anatomists and histologists of the 18th (Demours, 1741; Zinn, 1755) and 19th (Sir William Bowman, 1848; Virchow, 1885) centuries considered Vitreous a tissue. However, in 1930, Duke-Elder1 pointed out that Vitreous is not a tissue but a cell product. This is consistent with our current concept of Vitreous as an extended extracellular matrix composed primarily of water (98%), collagen and hyaluronan. The exact cells and processes responsible for the synthesis of these macromolecules are, as yet, unidentified. Also lacking is a comprehensive understanding of the supramolecular organisation of Vitreous, limiting the ability of investigators and clinicians to study Vitreous experimentally and evaluate it clinically. Indeed, even the roles of Vitreous in ocular physiology are not universally established. One probable function of Vitreous, however, is the maintenance of transparency within the eye (fig 1). This minimises light scattering and allows the unhindered transmission of photons to the retina for photoreception. Towards this end, Vitreous possesses biochemical properties that inhibit cell migration and proliferation.23 While essential for vision, the invisibility of Vitreous has obliged generations on both sides of the slit lamp and ophthalmoscope to merely look through Vitreous, unable to adequately look at it. Figure 1 Human Vitreous. The sclera, choroid and retina were dissected off the Vitreous body, which remains attached to the anterior segment. Although placed on a surgical towel and exposed to room air, the shape of the Vitreous body is spherical, and the gel is intact. The exquisite transparency of the Vitreous body is evident. Specimen courtesy of the New England Eye Bank. The absence of effective diagnostic techniques with which to evaluate Vitreous, both scientifically and clinically, has also hindered our ability …
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anatomy and pathology of the vitreo retinal interface
Eye, 1992Co-Authors: J SebagAbstract:Duke-Elder1 has stated that the first descriptions of vitreous structure proposed that the Vitreous was composed of 'loose and delicate filaments surrounded by fluid'. During the eighteenth and nineteenth centuries there prevailed no less than four different theories of Vitreous structure. In
Shigenobu Suzuki - One of the best experts on this subject based on the ideXlab platform.
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eye preservation treatment of retinoblastoma with Vitreous seeding
Japanese Journal of Clinical Oncology, 2003Co-Authors: Akihiro Kaneko, Shigenobu SuzukiAbstract:Retinoblastoma with Vitreous seeding has been one of the most challenging conditions for eye-preservation therapy. Several modalities for treating Vitreous seeding were reviewed in order to analyze the problems associated with them. External beam radiotherapy has been the most reliable method to treat Vitreous seeding. However, recurrence after external beam radiotherapy needs other types of treatments to preserve the eyeballs. Due to the progress of investigations concerning retinoblastoma, chemotherapy has become the most promising method to cure not only recurrence but also primary tumors. Systemic chemotherapy can rarely cure Vitreous seeding, but local chemotherapy using Vitreous injections of melphalan can preserve about 50% of the eyeballs with Vitreous seeding. Currently, animal experiments are being conducted to study the efficacy and safety of Vitreous surgery combined with infusion of anticancer drugs for eradication of Vitreous seeds and maintenance of visual function.
Mark S. Humayun - One of the best experts on this subject based on the ideXlab platform.
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Spatial Variations in Vitreous Oxygen Consumption
PloS one, 2016Co-Authors: Karthik Murali, Dongyang Kang, Hossein Nazari, Nicholas Scianmarello, Enrique Cadenas, Yu-chong Tai, Amir H. Kashani, Mark S. HumayunAbstract:We investigated the spatial variation of Vitreous oxygen consumption in enucleated porcine eyes. A custom made oxygen source was fabricated that could be localized to either the mid or posterior Vitreous cavity and steady state Vitreous oxygen tension was measured as a function of distance from the source using a commercially available probe. The reaction rate constant of ascorbate oxidation was estimated ex vivo by measuring the change in oxygen tension over time using Vitreous harvested from porcine eyes. Vitreous ascorbate from mid and posterior Vitreous was measured spectrophotometrically. When the oxygen source was placed in either the mid-Vitreous (N = 6) or the posterior Vitreous (N = 6), we measured a statistically significant decrease in Vitreous oxygen tension as a function of distance from the oxygen source when compared to control experiments without an oxygen source; (p
J. Samuel Zigler - One of the best experts on this subject based on the ideXlab platform.
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alterations in human Vitreous humour following cataract extraction
Experimental Eye Research, 2005Co-Authors: R. Neal, K C Winn, Donita Garland, Frederick A. Bettelheim, J. Samuel ZiglerAbstract:Abstract Cataract extraction is associated with the risk of posterior Vitreous detachment, macular edema and retinal detachment possibly as a result of a disturbance to the Vitreous body during surgery. While it is common for lens cortical fiber debris to leak into the Vitreous humour during cataract extraction, the extent to which the Vitreous humour is altered post-surgery is unknown. The current study examines the integrity of the Vitreous humour of pseudophakic and phakic human donor eyes by comparing the proteome, the viscosity and the size distribution of macromolecules in different regions of the Vitreous humour from human pseudophakic and phakic donor eyes. Major differences between the proteomes of anterior and posterior Vitreous humour were observed in phakic and pseudophakic donor eyes. Seventeen spots identified as complete, modified or cleaved forms of αA-, αB-, βA4-, βB2, and γS-crystallins were present in the anterior Vitreous humour of all pseudophakic eyes studied. Crystallins were not detected in the posterior Vitreous humour of the pseudophakic eye or the Vitreous humour of the phakic eye. Significant alterations in abundance and/or modification of transthyretin, alpha antitrypsin, and retinoic acid binding protein were observed in all locations of pseudophakic Vitreous humour as compared to phakic samples. In addition, a significant decrease in the number and intensity of protein spots was observed for the posterior Vitreous humour of pseudophakic eyes when compared to posterior Vitreous humour of phakic eyes. Proteins which were affected include antioxidant proteins and enzymes such as carbonic anhydrase and trisephosphate isomerase. A reversal of the viscosity gradient, anterior to posterior, in the Vitreous humour of pseudophakic eyes was observed concomitant with alterations in the distribution of 50 nm particles. These particles are likely primarily composed of hyaluronan. While varying degrees of Vitreous degradation may have existed prior to surgery and may have contributed to the cataract formation, in no case did the phakic donor eyes exhibit the same alterations in the Vitreous humour proteome, viscosity or particle sizes as did the pseudophakic donor eyes. The examination of phakic/pseudophakic donor eye pairs confirmed that the Vitreous humour proteome and structural integrity were very similar in the matched phakic donor eye to eyes from donors with no history of cataract. Even though the number of samples for this study was limited, the observed changes support the hypothesis that alterations in the Vitreous humour proteome occur in psuedophakic eyes with concurrent alterations in the structure of the Vitreous humor. These modifications of the microenvironment of the retina may contribute to the development of retinal complications following cataract surgery.
Raj Vardhan Azad - One of the best experts on this subject based on the ideXlab platform.
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Intracameral Triamcinolone Helps to Visualize and Remove the Vitreous Body in Anterior Chamber in Cataract Surgery
American Journal of Ophthalmology, 2005Co-Authors: Deependra Vikram Singh, Yog Raj Sharma, Raj Vardhan AzadAbstract:EDITOR: IN THE ARTICLE BY YAMAKIRI AND ASSOCIATES,1 THE AUthors addressed the problem of difficult visualization of Vitreous body after rupture of the posterior capsule and prolapse of Vitreous body. Complete removal of the Vitreous body is essential to avoid all serious complications associated with rupture of the posterior capsule. It is still not uncommon to find residual Vitreous body leading to complications in the postoperative period, which surprises and sometimes embarrasses the surgeon who had apparently removed it completely from the anterior chamber. The authors found the use of intracameral triamcinolone acetonide to be helpful in visualizing Vitreous body in six eyes with rupture of the posterior capsule and prolapse of Vitreous body but raised concerns about its use. We support the authors’ view that better visualization of Vitreous body will ensure complete removal after rupture of the posterior capsule, especially in difficult situations when corneal clarity is compromised or miosis is not achieved with intracameral pilocarpine. We have found 0.06% trypan blue to be very helpful to visualize Vitreous body after posterior capsule rupture. Trypan blue is known to stain Vitreous2 and has been found to be safe at lower concentrations (0.06%). 3,4 Use of 0.06% trypan blue offers additional advantages: it is safe for corneal endothelium at lower concentrations and for short exposure, 5 there is no significant toxicity reported despite widespread use for anterior capsule staining, it is unlikely to increase intraocular pressure, and it stains the anterior capsulorhexis margin, which helps intraocular lens implantation in the ciliary sulcus. Because the occurrence of posterior capsule rupture is unpredictable, triamcinolone acetonide may not be available for use, unlike trypan blue, which is used more frequently. Triamcinolone acetonide has the advantage of decreasing inflammation, which is more likely to occur after rupture of the posterior capsule and the prolapse of Vitreous body.