RESUMO
Considering the retina as an extension of the brain provides a platform from which to study diseases of the nervous system. Taking advantage of the clear optical media of the eye and ever-increasing resolution of modern imaging techniques, retinal morphology can now be visualized at a cellular level in vivo. This has provided a multitude of possible biomarkers and investigative surrogates that may be used to identify, monitor and study diseases until now limited to the brain. In many neurodegenerative conditions, early diagnosis is often very challenging due to the lack of tests with high sensitivity and specificity, but, once made, opens the door to patients accessing the correct treatment that can potentially improve functional outcomes. Using retinal biomarkers in vivo as an additional diagnostic tool may help overcome the need for invasive tests and histological specimens, and offers the opportunity to longitudinally monitor individuals over time. This review aims to summarise retinal biomarkers associated with a range of neurological conditions including Alzheimer's disease (AD), Parkinson's disease (PD), multiple sclerosis (MS), amyotrophic lateral sclerosis (ALS) and prion diseases from a clinical perspective. By comparing their similarities and differences according to primary pathological processes, we hope to show how retinal correlates can aid clinical decisions, and accelerate the study of this rapidly developing area of research.
RESUMO
BACKGROUND: Glaucoma comprises a group of neurodegenerative diseases resulting in retinal ganglion cell death within the optic nerve head. It is projected to affect almost 80 million people worldwide by 2020. The condition's asymptomatic nature translates to over half of glaucoma sufferers being unaware of their condition. By the time of diagnosis, irreversible blindness is likely to have occurred. Prime areas of glaucoma research therefore include identification and optimization of risk factors for the disease, accurate and early diagnostic tools and novel therapeutic methods. METHODS: The goal of this review was to summarize main areas of latest glaucoma research into risk factors of glaucoma, diagnostic tools and treatments. PubMed was used to search for terms including glaucoma risk factors, glaucoma diagnostics, glaucoma treatment, glaucoma drug delivery and glaucoma IOP. RESULTS: The evidence for risk factors of low CSF pressure, IOP, smoking, vascular risk factors and light toxicity is described. Latest diagnostic and monitoring techniques for glaucoma include SD-OCT, DARC and IOP telemetry. Current and emerging medical and surgical treatments in glaucoma are discussed. Rho kinase inhibitors have the potential to both lower IOP and also provide neuroprotection, several of which are in clinical trials. Several other new medical treatments such as calcium channel blockers and neurotrophic agents also have the capacity to provide neuroprotection. Minimally Invasive Glaucoma Surgery (MIGS) devices provide an improved safety profile compared to traditional trabeculectomy; the latest ab interno and ab externo devices are described. Novel drug delivery methods, including punctual plugs and contact lenses, help overcome the challenges with patient adherence. CONCLUSION: The ultimate goals are to reduce the individual patient risk factors associated with glaucoma, diagnose the condition early and to find treatments that not only reduce IOP but also reverse neurodegeneration of RGCs. The usage of combinations of novel medical and surgical treatments may help maximize IOP reduction and neuroprotection.