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Important Studies in Vitreoretinal Surgery
Published in Pradeep Venkatesh, Handbook of Vitreoretinal Surgery, 2023
MIVI-Trust study. In this study, 652 patients [464 in the ocriplasmin group and 188 in the placebo injection group] with focal symptomatic vitreomacular adhesion [VMA] were evaluated. Focal VMA was defined as attachment of the vitreous to the central 6-mm field of the macula with elevation of the posterior vitreous cortex. About 27% of patients achieved the primary end point of pharmacologic vitreolysis by day 28 [compared with 10% in the placebo group]. Secondary end points of total PVD [on ultrasonography] and closure of macular hole was achieved in 13% versus 4% and 41% versus 11%, respectively. In this study, patients with epimacular membrane had a significantly lower response. Vitrectomy rates were 18% and 27% in the ocriplasmin and placebo groups, respectively. Two patients in the treatment group developed retinal tear and detachment and were managed surgically.
Fibrinolytic Enzymes for Thrombolytic Therapy
Published in Peter Grunwald, Pharmaceutical Biocatalysis, 2019
Swaroop S. Kumar, Sabu Abdulhameed
Microplasmin is another plasmin variant generated by autolysis of plasmin at high alkaline pH (pH 11) and is a 29 kDa protein. It is a heterodimer made up of “A” chain with 31 amino acids and “B” chain with 230 amino acids (Wu et al., 1987). Micro-plasminogen can be recombinantly produced in Pichia pastoris and E. coli (Nagai et al., 2003; Ma et al., 2007). Bioengineering significantly reduces the overall production cost. On the other hand, it does not bind with fibrin since it is devoid of all the kringle domains of plasmin. Also, the rate of inhibition by α2-antiplasmin is very low with respect to native plasmin (Nagai et al., 2003). In vivo animal models and clinical trials proved its safety to be used as a therapeutic since it was not causing any hemorrhage (Suzuki et al., 2004; Chen et al., 2007; Thijs et al., 2009). Microplasmin (ocriplasmin) also finds application as therapeutic for vitreomacular adhesion. It causes vitreomacular detachment of fibronectin and laminin (Chen et al., 2008; de Smet et al., 2009). Ocriplasmin received FDA approval for treating vitreomacular adhesion and is commercially available under trade name JETREA®. However, its use as a cardiovascular drug is yet to be validated by further clinical studies.
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
Uveitis, an anti-inflammatory disease of the uvea, the layers of the eye underneath the sclera (ciliary body, iris, and choroid), requires the long-term intravitreal injection of anti-inflammatory agents. Triamcinolone is a synthetic glucocorticoid with anti-inflammatory properties and injected through intravitreal injections to patients unresponsive to topical treatment. A suspension is available in two strengths 40 mg/ml (Kenalog®, Bristol-Myers Squibb Company) and 80 mg/ml (Trivaris®, Allergan).7 Trivaris® is an 80 mg/ml triamcinolone acetonide suspension for intravitreal injection for the treatment of uveitis. Whereas Kenalog® is an injectable TA suspension for intramuscular and intra-articular injection for the ocular diseases sympathetic ophthalmia, temporal arteritis and uveitis. Ocriplasmin (JETREA®, Inceptua) a recombinant form of human plasmin approved in the year 2012 for the intravitreal treatment of vitreomacular adhesion. However, the use of Ocriplasmin has been discontinued due to the observed adverse side effects such as vitreous floaters, eye pain post injection and photopsia.
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
Pharmacologic vitreolysis using intravitreal Ocriplasmin (Jetrea; ThromboGenics NV, Leuven, Belgium), a recombinant protein for human plasmin was first approved for use for VMT and FTMH in 2012 following the Microplasmin for Intravitreous Injection—Traction Release without Surgical Treatment (MIVI-TRUST) trial.37 Its mechanism of action is to promote breakdown of fibronectin and laminin and thereby release the vitreous cortex from the ILM at the VMI. The trial found that release of VMT at 28 days was more likely in eyes treated with ocriplasmin (26.5%) as compared to a placebo injection (10.1%). In their sub-analysis, the success rate of VMT release was higher in those with focal VMT < 1500 μm and in those without an associated ERM (37.4% without versus 8.7% with ERM). The safety profile of Ocriplasmin however remains controversial. The MIVI-TRUST trial reported low rates of adverse events in eyes with ocriplasmin treatment, namely floaters, photopsias, transient visual loss and retinal tears. However, several post-market reports of dyschromatopsia, severe visual loss, electroretinogram changes, outer retinal disruption on OCT and dislocation of the crystalline lens after ocriplasmin have raised some concerns.38 Given its relatively low success rate, and possible adverse events, the use of enzymatic vitreolysis in VMT has been limited. However, it may be an option for those with focal VMT without ERM who are symptomatic but either decline or not medically fit for vitrectomy surgery.
Review of Vitreopapillary Traction Syndrome
Published in Neuro-Ophthalmology, 2020
Rami S. Gabriel, Chantal J. Boisvert, Mitul C. Mehta
New research has been ongoing in developing pharmaceutical agents that cause liquefication of the vitreous. Ocriplasmin (formerly microplasmin) is a recombinant form of human plasmin that contains proteolytic activity on proteins anchoring the vitreoretinal interface as well as lacking activity against type IV collagen-an essential component of the inner limiting membrane. This allows for targeted activity in the vitreous while minimising toxic effects to the retina.19 Trials have been conducted using this agent for VMT including two large randomised controlled phase 3 trials. Comparison of ocriplasmin injection to saline (placebo) has shown resolution of vitreomacular adhesion in 26.5% of eyes compared to 10.1%, respectively. Though these results are promising, many retinal specialists have abandoned the use of ocriplasmin due to its toxicity. Furthermore, its use in VPT would be limited due to the histopathological differences between VMT and VPT.