Is diabetic retinopathy a neurovasculopothy

“We have always been taught that diabetic retinopathy (DR) is a pathology of the inner retina, but I will present evidence that photoreceptors contribute to the problem,” Sobha Sivaprasad MD, Moorfields Eye Hospital, London, UK, told the 15th EURETINA Congress in Nice.“The fact that there is an absence of DR in patients with retinitis pigmentosa suggests that this is the case,” she said.

“Oxygen consumption is maximum at the photoreceptor level, as these cells contain most of the mitochondria found in the retina. This is particularly true during dark adaptation, when increased hypoxia generates VEGF production, leading to angiogenesis,” added Dr Sivaprasad.

Dark adaptation is most prevalent during sleeping hours, offering an otherwise overlooked moment for treatment via several routes. Dr Sivaprasad presented fascinating results of several studies in which a mask was worn by patients that illuminated one eye at night and left the other one dark. The illumination prevents dark adaptation and thus, presumably, hypoxia.

“The eye treated with nighttime light therapy showed decreased signs of DR, while the untreated eyes continued to show progression of DR,” she said.

CLEOPATRA, a multicentre, phase III randomised controlled trial is now ongoing to further test this modality. “Targeting photoreceptor hypoxia in DR might also be possible via supplemental nighttime oxygen, such as continuous positive airway pressure (CPAP) therapy, in patients with DME with obstructive sleep apnoea,” said Dr Sivaprasad.