Dench suffers from macular degeneration, an age-related condition that leads to a gradual loss of vision, which her mother also had.
"I never want to make much of it, but it is difficult – very, very difficult.
"I can't read any more. I can't paint like I used to. I try to watch movies, but it's quite difficult. But these are all of the negatives. I don't want to really think about all that. What I can do, I do. And I somehow get by."
But Dench, who has recently undergone surgery on her knee, insists she has no plans to retire.
"I heard a woman being interviewed on the radio the other day who was 105, and I expected this very frail voice, but this wonderful voice came out and she said to this reporter who was interviewing her, 'I'll tell you one thing,' she said, 'Don't stop anything. I never stop anything I'm doing because otherwise I'll never get started again.' And I thought, 'That'll do.'"
Exercise could help prevent age-related blindness
In the same week New Scientist ran a report of research carried out in the US which has shown that exercise protects the retina from degeneration and blindness, at least, in mice.
"Macular degeneration is one of the leading causes of blindness in the elderly, and affects about 30 million people worldwide. Eyesight deteriorates due to the death of light-detecting cells in the eye, called photoreceptors.
Exercise has already been shown to help reduce the risk of dementia and Alzheimer's disease, and has helped with the recovery of people with traumatic brain injuries or stroke. To explore whether exercise might also help with retinal diseases, Machelle Pardue and her team designed a month-long exercise regimen for mice.
One group was made to walk on tiny treadmills for an hour a day, five days a week for a month. Two weeks into this regimen, the team exposed the mice to harmfully bright light for 4 hours. This is a common way to artificially induce the degeneration of photoreceptors.
While this first group of mice exercised for a month, a second group remained inactive. These sedentary mice were kept in cages with stationary treadmills – to make sure they had the same visual stimuli in their habitats. Two weeks into the experiment, this group was also exposed to 4 hours of the bright light.
Twice as good
At the month's end, Pardue and her team compared the retinal function and photoreceptor counts of the two groups. Neural firing in the retinas of the mice that exercised was twice the strength as the inactive group, showing that their eyes were functioning better. Dissections also showed that the exercised mice kept roughly twice the number of healthy photoreceptors as inactive mice.
Pardue thinks the benefits could be down to a protein called BDNF which is important in keeping neurons healthy. BDNF is produced during physical activity in both mice and humans.
At the end of the experiment, mice that had worked out had 20 per cent more of the protein in their retinas compared with the inactive mice.
Pardue hopes that these initial findings will lead the way to human clinical trials testing the benefits of exercise on retinal health.
The three blind mice should have kept on running!