Inviato: Mer 17 Ago, 2005 10:11 Oggetto: Vitrectomia e cataratta
un recente studio riguardante l'insorgenza della cataratta a seguito dell'asportazione del vitreo è stato pubblicato dalla washington university di st. louis.
la novità di questa ricerca è rapresentata dall'osservazione che una delle possibili cause sia l'elevata presenza di ossigeno nella composizione del gel preposto alla sostituzione del vitreo.
per questo motivo gli auotri si propongono di realizzare un nuovo tipo di polimero in grado di creare una barriera protettiva per il cristallino.
il link dell'articolo è:
Kaohsiung J Med Sci. 2001 Feb;17(2):84-9. Related Articles, Links
Cataract formation after pars plana vitrectomy.
Chung CP, Hsu SY, Wu WC.
Department of Ophthalmology, Kaohsiung Medical University, No. 100, Shih-Chuan 1st Rd., Kaohsiung, Taiwan.
To investigate the duration and pattern of cataract formation after pars plana vitrectomy, thirty-three eyes from 33 patients with complete data from March 1995 to January 2000 were collected in this study. The time and pattern of cataract formation was analyzed according to Lens Opacities Classification System III (LOCS III). The correlation between the mean cataract progression and follow-up time was determined by simple regression and correlation analysis. Diabetes mellitus and hypertension were the main causes of patients with vitreoretinopathy who underwent pars plana vitrectomy procedure. Twenty-one patients (63.6%) had diabetes mellitus and 11 patients (33.3%) had hypertension. Four eyes (13.8%) received intravitreal gas injection after pars plana vitrectomy. The correlation between cataract progression and follow-up time was clinically significant (p < 0.05). Thirty-one patients (94%) were nuclear cataract, the mean time of cataract formation being 9.1 months; 15 patients (46.9%) were cortical cataract, the mean time of formation being 8 months; and 24 patients (72.7%) were posterior subcapsular cataract, the mean time of formation being 13.3 months. Cataract formation after pars plana vitrectomy is not infrequent. Nuclear cataract is the most common type in this study. Vitreous microenvironmental changes, post-vitrectomy uveitis, intravitreal gas, and patient age may be the key points of cataract formation after surgery. The mechanism of longer-term effect of pars plana vitrectomy on lens status is still unknown and merits further study.
Phase 2 Clinical Trial for OT-551 in Cataract Prevention, Othera Pharmaceuticals Category: Eye Health/Ophthalmology News Article Date: 14 Nov 2005
Othera Pharmaceuticals, Inc., a specialty pharmaceuticals company focused on treating eye disease, announced that it has initiated a Phase 2 clinical trial of its lead compound, a topically administered eye drop, OT-551.
The twelve-month, double-masked, randomized, placebo-controlled study is designed to evaluate the ability of OT-551 to prevent or arrest the progression of cataracts in patients who have undergone vitrectomy surgery, a procedure to correct retinal defects. OT-551, which has been shown to be a potent catalytic antioxidant, recently completed a Phase 1 safety and comfort study in healthy volunteers.
“It is generally accepted in the ophthalmology community that a link exists between vitrectomy surgery and subsequent cataract formation,” said Dr. Leonard Parver, Othera's Medical Director and a practicing retinal surgeon. “Removal of the vitreous from the back of the eye exposes the lens to oxygen free radicals, and in the great majority of the cases where the patients have their natural lenses, vision-impairing opacities will form within 9-12 months. Moreover, the cataract that forms is most often a nuclear cataract, the most common type, which is the same as the age-related cataract that occurs in a large percentage of the elderly population.”
Preclinical research results indicate additional uses for OT-551, including treatment of early stage and advanced dry age-related macular degeneration (AMD) by protecting against retina photoreceptor cell death and inhibiting angiogenesis, the growth of small blood vessels leading to the wet-form of AMD. A leading cause of vision loss, AMD affects approximately 10 million Americans.
“OT-551 is a novel small molecule that is topically dosed in an eye drop and has the unique ability to penetrate cell membranes and reach both the front and the back of the eye,” said David S. Joseph, chairman and CEO of Othera Pharmaceuticals. “In addition to cataract treatment, we are very encouraged by research results demonstrating that OT-551 may be able to treat AMD, as well as dry eye syndrome. We expect to begin Phase 2 trials for these indications next year.”
About Vitrectomy Surgery and Post-Vitrectomy Cataracts
Approximately 200,000 vitrectomies are performed by retinal surgeons in the U.S. each year for retinal repair. The procedure typically involves removal of the vitreous, the gel-like substance that acts as a barrier and fills the back of the eye. In removing the vitreous, the patient's lens is suddenly exposed to oxygen from the blood vessels in the retina. Oxygen free radicals are produced as a result and these then damage proteins in the nucleus of the lens. These damaged proteins aggregate, resulting in opacification of the lens and formation of vision-impairing cataracts. The post-vitrectomy cataract that forms as a result of oxidative damage is a nuclear cataract, the same as the more common age-related cataract, which affects as many as 35 million Americans.
About Othera Pharmaceuticals
Founded in 2002, Othera Pharmaceuticals, Inc. is a specialty pharmaceuticals company focused on developing treatments for major age-related eye diseases. In addition to its lead compound, OT-551, Othera is also developing OT-730 as a novel improved beta-blocker for treatment of glaucoma. OT-730 is designed to have excellent beta-blocking activity in the eye, yet easily break down into inert components upon entry into the bloodstream. Today's marketed beta-blockers as a class are the most widely-prescribed drugs by volume for glaucoma, but suffer from the potential danger of systemic side effects. Initial preclinical studies support the concept that OT-730 could overcome the systemic side effect problem, and Phase 1 and Phase 2 clinical trials to demonstrate safety and efficacy are planned to begin in 2006.
a pochi giorni dalla laurea, rieco a visitare il forum solo a queste ore sospette. ho trovato un interessante riferimento all'articolo postato da the cube:
Cataract A novel concept in cataract therapy is a drug intended for cataract prevention. OT-551 (Othera Pharmaceuticals) is intended to counteract the detrimental effects of free radical-induced oxidative damage. This type of damage is one of the primary causative mechanisms in cataract formation. Antioxidant molecules such as OT-551 could have potential applicability in the treatment or prevention of several types of ocular disease in which oxidative damage plays a role. The Othera agent is an antioxidant molecule (Tempol H) that has been modified for ease of delivery and penetration in a topical form.
se non sbaglio anche nella degenerazione vitreale svolgono un ruolo fondamentale i radicali liberi. datemi conferma...
Eye Drop in Testing to Prevent Cataracts in Vitrectomy Patients
EXTON, Pa., November 2005 — Othera Pharmaceuticals began a phase II clinical trial of an eye drop called OT-551, to see if it can prevent or slow the progression of cataracts in people who have undergone vitrectomy surgery. A vitrectomy is the removal of vitreous from the back of the eye; it is performed to correct retinal defects.
"It is generally accepted in the ophthalmology community that a link exists between vitrectomy surgery and subsequent cataract formation," said Dr. Leonard Parver, a retinal surgeon and the medical director for Othera. "Removal of the vitreous from the back of the eye exposes the lens to oxygen free radicals, and in the great majority of the cases where the patients have their natural lenses, vision-impairing opacities will form within nine to 12 months."
OT-551 will also be evaluated for treatment of early-stage and advanced dry age-related macular degeneration (AMD), by protecting against retina photoreceptor cell death and inhibiting angiogenesis, which is the growth of new blood vessels that could lead to the wet form of AMD.
un interessante aggiornamento su questo farmaco che sembra davvero essere promettente nel prevenire o rallentare l'insorgenza della cataratta dopo un intervento di vitreoctomia:
ancora buone notizie sulla sperimentazione del collirio OT-551. se tutto procede per il meglio, la sua commercializzazione è prevista a partire dal 2009:
l'OT-551 è attualmente giunto alla fase 2 di sperimentazione. è l'unico collirio fino ad oggi studiato in grado di raggiungere il vitreo e la retina.
la sua applicazione immediata è nel trattamento della cataratta, fra cui quella derivante dall vitreoctomia. studi preclinici hanno dimostrato la sua efficacio anche nella cura della degenerazione maculare.
un prodotto analogo l'OT-730 è invece in corso di studio per il trattamento ndel glaucoma.
si tratta di una nuova, grande strada per il reperimento di metodi non invasivi nella cura di patologie oculari.
alcuni link per scoprire gli indirizzi della ricerca finalizzati a migliorare le conseguenze della sostituzione del cristallino a seguito di un'operazione di cataratta:
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