Researchers found that visualisation of disruption of the retinal pigment epithelium (RPE) layer of cells can show risks of the choroideremia disease and impact future gene therapy trials.

A study by the National Eye Institute (NEI) used adaptive optics with indocyanine green dye to view live cells, including light-sensing photoreceptors, RPE cells, and choroidal blood vessels, and found that the degenerative disease, choroideremia, caused enlarged RPE cells in both males and females.

This suggested that the RPE blood barrier function may be altered in choroideremia, similar to the changes seen in age-related macular degeneration, and enabled a signpost for monitoring the risk and progression of diseases in patients.

As RPE cell enlargement could also be shown when using only a commercially available scanning laser ophthalmoscope alongside dye, this method could be widely adopted by clinics, according to the study.

Johnny Tam, head of the NEI clinical and translational imaging unit, said: ‘One major finding of our study was that the RPE cells are dramatically enlarged in males and females with choroideremia. We were surprised to see many cells enlarged by as much as five-fold.

‘It’s not obvious at first, but using an existing tool in the clinic, we can monitor and track the cellular status of the RPE layer. This could prove valuable in identifying which patients would benefit the most from therapeutic interventions.’

However, future studies comparing rod photoreceptors and RPE cells in vivo are warranted, as it is not possible to view the state of rods through imaging, an area which has also been reported as a key sign of degeneration in choroideremia.