Brief plain language background
Choroideremia, which predominantly affects men, causes the gradual breakdown of important components of the retina at the back of the eye. This includes photoreceptors (light responsive cells), the pigment cells that support them, and a layer of capillaries that provides the retina’s blood supply, called the choroid. Sight is lost over time, starting with the side vision (periphery), eventually leading to blindness.
What problem/knowledge gap does it help address
The research team have been working on a gene therapy for choroideremia. They observed that patients who had gene therapy in the early stages of disease – before their central retina was damaged – did not appear to have further degeneration.
Currently, regulatory authorities look for a gain of three lines of vision on the letter chart. Characterising the smooth zone area of the central retina – and the preservation of it following treatment – could be a potential indicator of success for future clinical trials.
Aim of the research project
To characterise the smooth zone of the retina in choroideremia patients and identify zone changes in early stages of the condition.
Key procedures/Objectives
- Study patients with early stage choroideremia, assessing retinal structure and function.
- Identify an international cohort of early stage patients with similar smooth zone characteristics.
- Follow up with patients from the previous clinical trial to determine long-term results of the gene therapy.
Potential impact on people with sight loss
An approved gene therapy offers a long-term treatment option for those with inherited retinal conditions. Where the current standards for approval mandate vision improvement, people with vision loss have expressed satisfaction at maintaining current levels. Identifying an endpoint for clinical trials that shows a slowing of degeneration could be beneficial for future inherited retinal gene therapy clinical trials.