The Use of Neuroprotective Agents in Treating Geographic Atrophy

Abstract

Geographic atrophy (GA) secondary to age-related macular degeneration accounts for close to one-quarter of cases of legal blindness in the USA and the UK. Despite this notable disease burden, the pathophysiology of GA is complex and not fully understood, and there is currently no approved treatment to prevent or slow its progression. GA is heterogeneous in its appearance and extent, and underlying associated traits such as drusen and complement factor polymorphisms vary between patients and by ethnicity, posing a challenge for treatment development. The root cause of vision loss in GA is photoreceptor death; therefore, protecting photoreceptors from damage and delaying their degeneration are key to successful GA treatment. There are multiple neuroprotective pathways that may contribute to protecting photoreceptors from damage, and compounds that target these pathways include antioxidants, neurotrophic factors, and catalases. However, the efficacy of previously trialled neuroprotective therapies in GA, such as brimonidine, tandospirone, and NT-501, has been inconsistent; this may be due to their target of action, method of delivery, and/or suboptimal duration of action. Neurotrophic factors, or molecules involved in neuroprotective signalling cascades, may be ideal agents for further investigation for the treatment of GA. Future neuroprotective strategies in GA must focus on the development of agents with a long duration of action that can combat the progression of chronic damage in GA to provide clinically meaningful benefits for patients.