What changes take place in the visual brain of people with AMD?

Research details

  • Type of funding: Project Grant
  • Grant Holder: Professor Tony Moreland
  • Institute: University of York
  • Region: North East
  • Start date: October 2014
  • End Date: September 2017
  • Priority: Treatment
  • Eye Category: AMD

Overview

Age related macular degeneration (AMD) is a leading cause of blindness in the UK. It happens when ‘photoreceptor’ cells in the macula stop working. The macula is the part of the light-detecting layer of the eye (the retina) that we use for central, detailed and colour vision. There is no cure at the moment.

Losing photoreceptors from the macula means that key parts of the brain that process vision (together called ‘visual cortex’) stop receiving signals from the eye. In turn, this can lead to visual cortex shrinking and could potentially mean that treatments to restore vision might have limited success because of changes to the visual brain.

So in this project the team is aiming to track the changes in shape and size of the visual brain and find out how it works over time after sight loss due to AMD. They are also testing to find out if stimulating the brain with small electrical currents can protect against changes in visual cortex due to AMD.

Tracking changes to the brain after sight loss, will give the researchers a timeframe or window in which treatments might work best. Successful use of brain stimulation techniques could potentially extend this window. It would be a non-invasive therapy that might be used alongside other future treatments to give sight back, such as stem cell transplants or gene therapy, to make them more effective.
  • Scientific summary

    Assessing the status of visual cortex in patients with macular disease.

    Age-related macular degeneration (AMD) is the leading cause of blindness in the UK. The loss of macular vision in both eyes means that a significant proportion of the visual cortex no longer receives input. The team’s research has shown that the region of the visual cortex that no longer receives input reduces in volume suggesting degeneration of brain tissue. This is a concern because the success of treatments to restore retinal function (with stem cell or gene therapy or visual prosthetics) may ultimately be limited by degenerative changes in the visual cortex.

    In this proposal the research team is tracking the changes in cortical anatomy and function over time in patients with bilateral AMD and central scotomas. This will allow them to determine the rate at which the brain changes structurally and functionally. They are also attempting to slow the rate of, or prevent structural and functional change in the visual cortex by applying a safe and clinically approved neurostimulation technique, transcranial Direct Current Stimulation (tDCS).

    The aims therefore are to determine the time window over which the cortex is viable and whether it can be extended with a safe and inexpensive treatment. The intended outcome is to ensure that cortex can remain viable so that treatments that restore retinal function are successful.