Abstract
Abstract: :
Purpose:Neovascular age-related macular degeneration (AMD) is a leading cause of vision loss in people over the age of 65. Current treatments include surgical (subretinal surgery and macular translocation) and nonsurgical (laser photocoagulation, photodynamic therapy, and transpupillary thermotherapy). These treatments have either limited success or applicability or have not been studied in a randomized, prospective fashion. Triamcinolone acetonide (TA) is an angiostatic steroid. It is relatively insoluble and has been used as a depot subtenon injection in the treatment of intraocular inflammation and macular edema. Experience with the intraocular use of TA has been limited. The use of TA in the treatment of neovascular age-related macular degeneration (AMD) has been investigated using a rat model of laser-induced CNV and intravitreal TA proved effective in treating the CNV. Experience in humans has been limited. Use of a 39-gauge instrument has been shown to result in self-sealing retinotomy and may be useful in delivering TA into the subretinal space with minimal mechanical trauma. A 39-guage delivery system may be a feasible and safe way to deliver TA into the subretinal space. Methods:18 pigmented rabbits were used. 0.1 cc of TA was administered to the subretinal space in concentrations of 3 mg/cc, 1.5 mg/cc, and 0.3 mg/cc using a 25-gauge system with a 39-gauge subretinal cannula. Control eyes received 3 mg/cc of intravitreal TA, subretinal vehicle, or subretinal balanced salt solution. Fundus examination (including fundus photography) and fluoroscein angiography were performed preoperatively and then on postoperative days 7, 14, 21, and 60. Ganzfeld electroretinography was performed on preoperatively and then prior to sacrificing the animals on postoperative day 60. Eyes were enucleated, fixed in formalyn and glutaraldehyde, and then processed for routine light and electron microscopic evaluation. Results:Clinical, functional, and histopathologic data demonstrate that subretinal TA can be safely administered into the subretinal space using a minimally invasive 39-guage cannula system in the rabbit model with minimal toxicity. Conclusion:Subretinal TA can be safely delivered into the subretinal space of rabbits with minimal toxicity. This may lead to an alternative method of treating neovascular AMD in humans.
Keywords: 554 retina • 436 injection • 460 macula/fovea