Last fall, Rob and his colleagues published the results of their study in *Translational Vision Science & Technology* on the impact of seasons, sunlight, and light sensitivity on depressive symptoms in adults with visual impairments.¹ The study combined data from seven studies conducted between 2009 and 2019, involving a total of 1,925 adults with visual impairments in the Netherlands. Participants reported on depressive symptoms using the comparable PHQ-9 and CES-D questionnaires. By linking the reporting date to the season, the number of daily hours of sunshine (from the KNMI weather station near their place of residence), and self-reported light sensitivity, associations between these factors could be identified.

Factors

The study concludes that the season, sunlight, and light sensitivity likely play a role in depression among people with visual impairments. In the general population, depression is more common in the winter than in other seasons, primarily due to a lack of light. Previously published research shows that the risk of depression among people with visual impairments is already higher, regardless of the season.² Rob: “There are a number of underlying factors: people with visual impairments are less mobile, have a harder time finding work, and have a smaller social network, which can lead to feelings of gloom. In addition, limited exposure to light also plays a role. The stimulus of light does reach them through the eye, but to a lesser extent. When there is less daylight available, this has an even greater impact than it does on people with normal vision.”

Disruption of the circadian rhythm

When there is less light, the brain produces less melatonin, which can lead to sleep problems. “Normally, the body detects when it gets dark and then produces more melatonin, but the difference between dark and light is much smaller for people with visual impairments. This is caused, on the one hand, by their damaged retinal ganglion cells, which transmit the light signal less effectively, and, on the other hand, by the fact that these people spend less time outdoors anyway. If the light stimulus is already weak during the day, the hormonal rhythm—and thus the circadian rhythm—becomes disrupted.”

Rob advises optometrists to thoroughly inform their patients: “The main finding of our study is that the more a person is exposed to sunlight, the fewer depressive symptoms they experience.” For people with visual impairments, the advice is therefore to go outside as much as possible or sit by a window. In principle, this applies to everyone, but it is even more important for this group because visual stimuli are much more difficult for them to perceive.”

Photophobia

Rob’s research also focuses on sensitivity to light, or photophobia, which is strongly linked to symptoms of depression. “We initially thought that people with photophobia feel down because they seek out light stimuli less often and therefore spend less time outdoors. But it turns out that photophobia can also lead to irritated and painful eyes, which makes people feel less comfortable in their own skin. Finally, spending less time outdoors can also lead to a smaller social network. People end up living more isolated lives because they have difficulty coping with light exposure.”

There are aids, such as sunglasses, but they, in turn, also block light. “Especially in the winter, sunglasses can make it even darker, which can worsen feelings of gloom. At the same time, sunglasses can encourage people who would normally stay indoors to go outside instead.” Whether the benefits outweigh the drawbacks varies from patient to patient—so it’s a matter of trial and error.

Referral

There are various options for psychosocial support. “It’s important for optometrists to be alert to signs of depression,” he emphasizes. “If patients don’t seem to be feeling well, it’s good to know that they can get help, provided they have a referral from their primary care physician or ophthalmologist. For example, they can turn to Koninklijke Visio or Bartiméus, where psychologists and social workers are available to provide support. So there are various options, but healthcare providers need to be aware of them.”

Encouraging patients

Rob is currently conducting a follow-up study at Amsterdam UMC, in which ophthalmologists, optometrists, and ophthalmic technicians identify whether patients with visual impairments are experiencing symptoms of depression. Rob is no longer recruiting new participants for the study.

He emphasizes the importance of being vigilant for signs of depression in every patient with a visual impairment, regardless of the eye condition. According to him, the prevalence of low mood in this group is high, and the impact of light on this is often underestimated. His advice to optometrists: encourage patients to go outside every day and inform them about the options for mental health support.

The Potential Role of Light Therapy

Light therapy may play a role, in which patients sit in front of a lamp that simulates daylight for half an hour every morning. To date, little is known about the effect of this intervention on people with visual impairments. However, results from a small pilot study were published in 2021.³

Rob: “Light therapy may not be the best way to support someone who has been feeling down for years, because in that case, there’s a good chance the symptoms have a different cause. For seasonal depression, however, light therapy might be an option.” Further research is needed on these and other treatment options for seasonal depressive symptoms in this population.

Light therapy may also hold promise for people who are completely blind. “At first glance, you might think that light therapy wouldn’t work for them, but there are studies showing that light signals do reach them after all.”⁴–⁵ It varies depending on the eye condition: certain cells function in some cases, while in other conditions they do not. It’s unclear exactly how this works, but it does offer hope.”

This article was previously published on the Macula Association’s website