Unravelling the relationship between vision and sleep

The connection between vision and sleep was explored during Dr Ian Beasley’s 100% Optical presentation (1 March, Excel London).

The AOP head of education and OT clinical editor is currently undertaking a MSc in sleep medicine at the University of Oxford.

Beasley highlighted that the presentation would explore the “two-way street between vision and sleep.”

“Firstly, we'll consider what happens to sleep regulation in cases of severe visual impairment, and then we'll look at the other side of the coin: how do sleep disorders compromise ocular integrity?” he said.

The optometrist noted that during his three decades working in optical practice, sleep was seldom on his radar when dealing with patients.

“It's easy to assume that sleep sits outside of our professional remit, but as we'll see, biologically, the retina is the gateway through which environmental light sets the timing of every organ system in the body, and that gives this topic real relevance to us as primary eye care practitioners,” Beasley observed.

He noted that between 50 and 70% of patients with severe sight loss develop a circadian disorder.

Beasley added that around one in 10 people are living with obstructive sleep apnoea – which can compromise the eye in a range of ways.

He reflected on the different ways that sleep can improve people’s lives – from appetite control to enhanced decision making and quicker recovery times.

“If sleep were a supplement, it would be permanently sold out,” Beasley said.

Beasley outlined the role of the non-visual pathway in sleep – including the suprachiasmatic nucleus (SCN). He highlighted that the SCN acts as the body’s internal timekeeper.

“Its job is to detect light, keep time, run the show. Even before the sun is fully up, your body is already shifting gears,” he explained.

Beasley added that the SCN is not working in isolation.

“As well as the SCN acting as the master clock. We also have peripheral clocks. Your liver keeps time, your skeletal muscle keeps time, your pancreas keeps time, even your gut microbes are running their own daily schedule,” he said.

He added that the circadian period is typically slightly longer than 24 hours – which means that without daily light input, the body clock would drift by about 12 to 18 minutes each day.

“Over weeks, this would become profoundly disruptive. It's a small biological mismatch with large functional consequences,” Beasley shared.

He compared the effect of not being able to reset this internal clock to a feeling of jet lag.

“Thankfully, jet lag is a relatively short phase, and we just push through that feeling a bit grotty until we realign our circadian clocks. But imagine if you had to live with jet lag for the rest of your life,” Beasley said.

Patients who can no longer reset their circadian clocks – for example, because of severe sight impairment – may be diagnosed with non-24-hour sleep-wake rhythm disorder.

If sleep were a supplement, it would be permanently sold out

The effect of sleep disruption on the eye

During his presentation, Beasley outlined associations between obstructive sleep apnoea (OSA) and ocular disease.

He noted that patients with OSA have a 50% higher chance of developing glaucoma and a four-fold increase in the risk of developing non-arteritic anterior ischemic optic neuropathy.

Beasley highlighted that, among patients with diabetic retinopathy, severe OSA substantially increases the risk of progression.

He added that treating OSA with continuous positive airway pressure appears to attenuate the elevated risk of some eye conditions.

“Asking about sleep arguably belongs in routine eye care, because we're often the first clinicians to see the structural consequences of systemic sleep disease,” he said.