I would think her ophthalmologist's office would have connections with groups or services to provide support for people who are losing their sight. I don't know of any materials specifically related to wintersowing that might help. But, in this day and age of technology, there must be a program that could read the wintersowing forum posts to her, and she could give verbal commands to explore the Internet. If such a program doesn't exist, there is a great opportunity for someone who knows their way around a computer.

Check out VisionAware or the Royal National Institute for the Blind. Also, any British gardening book will not differentiate between sowing and 'winter-sowing' - this is NOT a unique US thing nor does it require special equipment such as particular milk jugs... but has been practiced since time immemorial - any beginners gardening book will take your friend through the basics of seed sowing (at various times of year - not just winter - and can often be found as audio books, books with large print or even braille. There is also a huge amount of info on sensory gardening for the visually impaired, both taking a hands -on approach to growing and sowing, with emphasis on texture, fragrance, sound...as well as visual appreciation. There is a whole world to explore and for many people with visual impairment, horticultuire does indeed provide a great resource for intellectual and emotional stimulation.

There are quite a few videos on you tube, they are all pretty short but it may help her. Here is a link to one of them: https://www.youtube.com/watch?v=r6aSoaxdFo0