Undertaking a Go Ape experience was amongst the things a woman wished to do before going completely blind.

Tiggi Trethowan, 65, who lives in Somerset, lost her sight in her right eye about 15 years ago and is down to 6 per cent sight in the left eye, with doctors telling her: “My eyesight is hanging off a cliff edge of dental floss which could break at any time.”

With that in mind, Tiggi has been on a mission to complete items on a ‘visual memory list’, which includes visiting an Australian island with a population of nine and exploring Antarctica, before she goes completely blind.

The diagnosis means she will eventually go completely blind, fueling Tiggi's need to create a “visual memory list” including places she loves to visit and wants to travel to.

A sighted guide is always with her on the trips, alongside black Labrador Jackie, who Tiggi got around five years ago through Guide Dogs and is her “absolute life”.

“Even before I found out I had 6 per cent of my sight in the left eye, I realised that the opportunities others have of being able to look at a beautiful painting or look at pictures in a photo album - when my sight was completely gone - would not be an option."

“My choices were to climb into bed, put the duvet over me and never get up again, or get up and revisit places I have loved and people I have loved.”

So far she has been to new places including Patagonia, Chile and Argentina, with the “most dramatic” being Antarctica, which she travelled through on a fishing boat with her guide.

Last month Guide Dogs surprised Tiggi by organising for her to take on Go Ape Bracknell’s Treetop Challenge, which includes tree-to-tree crossings and ziplines, with the help of Mark “Billy” Billingham, 57, from Channel 4’s SAS: Who Dares Wins.

“There were so many ropes and harnesses, so for somebody with 6 per cent sight, it was a challenge,” Tiggi said.

“But I literally threw myself into it and the good thing about being blind is that I can’t see where the ground is, so it didn’t really matter.

“I can’t tell you how kind Billy was. He never pushed me, but was always there to support me.

“We did the really big zip line together and I turned to him and said ‘have I broken you’ and he said ‘finally, you have broken me’.”

Mark, who is based in Herefordshire and also spends a lot of time in Lake Worth, Florida, said it was an “absolute pleasure” to be involved.

“Tiggi is like a little generator, she is always smiling and full of positive energy, and she’s a little trickster as well.

“She actually put me through my paces, if I’m honest, and I think I was more nervous than she was.

“[On the final zipline], it was actually quite tough, but there was no stopping her – she grabbed on to my hand and just went off and she screamed and we crash landed at the bottom and it was a really nice moment.”

He added that Tiggi is a great example of someone who has faced an obstacle and overcome it.

“Everyone is going to face a dark space or obstacle,” he said.

“It’s just an obstacle and the quicker we attack that obstacle and the faster we get through it, the faster we enjoy what we should be enjoying again.”

Tiggi has advised people who may be worried about losing their sight to “never give up, never give in”.

“It’s a diagnosis. Yes, it could potentially be life-limiting, but it is not life-threatening.

“It is simply a form of renavigation.”

The remaining items on the list include travelling to Costa Rica to visit Fortuna Sloth Sanctuary, a trip to Kenya, a country she previously visited while working on a documentary with Amref Flying Doctors, and revisiting Dirk Hartog Island, in Australia, which has a population of nine.

Guide Dogs provide a sighted guide service to support people with sight loss to live the life they choose.

More information about becoming a Guide Dogs ‘My Sighted Guide’ volunteer can be found at guidedogs.org.uk