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Pharmacologic vitreolysis
Published in A Peyman MD Gholam, A Meffert MD Stephen, D Conway MD FACS Mandi, Chiasson Trisha, Vitreoretinal Surgical Techniques, 2019
In contrast to dispase, which induces PVD only, hyaluronidase acts on hyaluronan and liquifies the vitreous. From theory and in practice, there is no primary effect at the vitreoretinal interface. Liquefication without weakening vitreoretinal adherence, however, may worsen matters significantly by exacerbation of vitreoretinal traction.1 This state is present in common conditions that are prone to retinal detachment, such as myopia, and in hereditary arthroophthalmopathies, such as Stickler’s syndrome.1,46 Generalized or more localized synchisis in the presence of persisting vitreoretinal traction is the pathologic hallmark of vitreo-retinal traction syndrome or macular holes.47,48 At present, it is unclear whether hyaluronidase may act on the vitreoretinal interface, thereby possibly preventing synchisis without syneresis. The results of the phase III clinical trial have not yet shown any adverse effects on retinal tear formation and retinal detachment.13
Nail Product Rheology
Published in Laba Dennis, Rheological Proper ties of Cosmetics and Toiletries, 2017
An important property of nail polish is its appearance in the package. Unlike many other products, nail polish is most usually sold in a glass bottle in which the consumer may observe the physical condition. This may offer an advantage, making a color statement and allowing the effects imparted by pearlescent pigments or glitter to be visible at the purchase point. The addition of these materials caused much effort to be put into development of systems capable of creating excellent shelf appearance. On the other hand, the “cure” that was developed can cause deleterious side effects. Failure of the suspension system can lead to separations, syneresis, or overgelation. Syneresis is a condition in which a liquid layer separates from the mass. Overgelation occurs when the nail polish becomes semisolid, and has the appearance of curdled milk in its more severe state. Often the pigments are no longer homogeneously dispersed when this occurs. The nail polish appears spoiled to the consumer.
Vitreous Humor: Composition, Characteristics and Implication on Intravitreal Drug Delivery
Published in Current Eye Research, 2023
Deepakkumar Mishra, Shilpkala Gade, Katie Glover, Ravi Sheshala, Thakur Raghu Raj Singh
One of the physiological condition that could severely impact diffusion of molecules in vitreous humor is liquefaction. The age-related degradation of vitreous humour can also cause the liquefaction of vitreous that is known as syneresis. The research suggests that approximately 20% of vitreous humor exists in liquid state by the age of 14–18 years, which tends to grow up to 50% by the age of 80–90 years. The syneresis is governed by the aggregation of collagen fibrils present in the solid vitreous that leads to redistribution of collagen content in the eye. The other hypothesis suggests that degradation of collagen fibrils b chondroitin ABC lyase can also lead to aggregation of collagen fibrils and further progression of syneresis. This degradation and redistribution of collagen is a major reason for the posterior vitreous detachment (PVD). PVD is a gradual process of splitting away of the cortical vitreous gel from ILL on the inner surface of the retina. It is a common occurrence and can affect up to 25% population. The PVD progression is gradual process and can range from early PVD, i.e. early stages of vitreous liquefaction and weakening of post-basal vitreoretinal adhesion, to complete PVD, where the vitreous is completed detached from the inner limiting membrane and the retinal layers.19 (Figure 6)
Anterior Uveitis Due to Intracameral Moxifloxacin: A Case Report
Published in Ocular Immunology and Inflammation, 2021
Marcela Peñaranda-Henao, Juliana Reyes-Guanes, Juliana Muñoz-Ortiz, ngela María Gutiérrez, Alejandra De-La-Torre
The patient attended the uveitis consultation with a best-corrected visual acuity (BCVA): 20/20 OD and 20/20-2 OS. External examination showed normal qualitative esthesiometry and pupil deformation with associated poor pupillary reaction. Slit-lamp examination in OD was positive for keratic precipitates without inflammation signs and endocapsular IOL. In OS was positive for ciliary injection, fine pigmented keratic precipitates (Figure 1c), 1+ flare and 1+ cells in the anterior chamber (SUN Classification, 7) iridial zones of atrophy (Figure 1 d,e) with diffuse transillumination defects, discoria, and endocapsular IOL. Intraocular pressure (IOP) was 12/22 mmHg. Fundoscopy positive findings were: OD normal; OS: 0.5+ pigmented cells in the anterior vitreous, syneresis without cellularity or haze in the posterior vitreous, cup-disk ratio (CD) 0.6 and macula with mild decrease in foveal brightness. The results of PCR in aqueous humor of OS were negative for Toxoplasma, CMV, EBV, VZV, HSV 1 and 2, bacteria and Mycobacterium tuberculosis.
Vitreomacular disorders: a review of the classification, pathogenesis and treatment paradigms including new surgical techniques
Published in Clinical and Experimental Optometry, 2021
Mali Okada, Daniel Chiu, Jonathan Yeoh
At birth, the collagen fibrils are arranged as a structured gel. Beginning in early adulthood, however, there is a progressive increase in hydrated spaces within the vitreous in a physiological process called synchysis senilis.3,4 There is a corresponding decrease in the vitreous gel volume, resulting from a fragmentation of the collagen-hyaluronic structure, which is termed syneresis. Previous histological studies reveal that by age 80 years, more than half the vitreous gel volume has undergone age-related gel contraction, with light and electron microscopy revealing breakdown of the collagen vitreous meshwork and an increase in liquefied spaces within the gel.4 The liquid that is formed passes through defects in vitreous cortex, leading to fluid-filled pockets which separate the posterior hyaloid face from the retina. This process usually begins in the perifoveal region with shallow detachment of the vitreous gel but can also occur peripherally. Over time, these fluid-filled pockets coalesce, resulting in a total detachment of the posterior vitreous cortex, with complete vitreopapillary separation, Figure 1. Clinically this is often visualised as an elevation of glial tissue over the disc, known as a Weiss ring. The evolution of posterior vitreous detachment (PVD), as imaged by OCT, has been characterised as following five stages, Figure 2.5