Myopia affects 30% of the population in the U.S. and Europe, and 70-90% of the population in some Asian countries. High myopia of greater than 8 diopters affects 0.2 0.4% of the US population and up to 1% of the population in Asian countries. The principal change associated with degenerative myopia is progressive stretching and thinning of scleral tissues leading to posterior staphyloma formation. As scleral tissues stretch and thin, there is associated stretching of retinal and choroidal tissues that promote visual loss. Indeed, degenerative myopia is the leading cause of untreatable blindness in China, Taiwan, and Japan, and is ranked 7th in the United States. While visual loss from macular atrophy and choroidal neovascularization are most common in degenerative myopia, patients with this disease are also more prone to retinal detachment and macular hole formation. Although a large population is affected by this disease worldwide, there is currently no effective method to arrest progression and reduce the rate of visual loss. A proprietary treatment developed through collaboration of Visdex, Caltech and UCSF successfully stabilizes scleral shape and prevents globe enlargement in vitro. The treatment consists of topical application of the formulated drug candidates to the surface of the sclera, allowing the drug molecules to diffuse into the tissue and then irradiating the sclera with visible light. The procedure requires approximately 10 minutes and the drug candidates have been approved by the FDA for use in patients. Initial in-vivo experiments in rabbits show that the drug candidates and irradiation are well tolerated by the eye. The objective for this Phase II STTR project is to demonstrate that such a treatment can be translated into a clinically meaningful protocol that shows efficacy in an animal model of myopia. Based on in-vitro efficacy and in-vivo biocompatibility observed in Phase I, this innovative treatment will be optimized in vitro for stabilizing scleral shape in an intact eye expansion test (Aim 1), adapted to surgical procedures for administration of the drug candidates and irradiation in vivo and evaluated for toxicity and efficacy in a rabbit model (Aim 2), and tested for the ability to prevent myopia in vivo in a guinea pig model of degenerative myopia (Aim 3). This Phase II research and development effort will culminate in a treatment that halts progression of degenerative myopia by stabilizing the sclera. The subsequent Phase III development will be a continuation leading to human clinical trials and FDA approval.
Degenerative myopia is a progressively worsening condition in which the sclera thins and stretches, leading to globe elongation and damage of retinal and choroidal tissues. Although degenerative myopia affects nearly 1 million people in the United States, and approximately 20 million people worldwide, there is currently no effective treatment method. This project will result in an innovative, light-activated treatment that will arrest stretching of the sclera and prevent the associated retinal complications that lead to blindness.
| Mattson, Matthew S; Huynh, Joyce; Wiseman, Meredith et al. (2010) An in vitro intact globe expansion method for evaluation of cross-linking treatments. Invest Ophthalmol Vis Sci 51:3120-8 |
