However, accommodating David's disability was the least of problems for the pair. Learning how to communicate effectively was the first, and most important, step, David says.
"Because I can't see body language, we really needed to communicate well verbally; we really had to work on that.
"The worse thing for a blind person is the silent treatment – generally we always say what we want at the time," he says.
The couple met at a youth camp and managed a three-year long-distance relationship by sending tapes to each other. Most weekends, David would take a seven-hour bus ride from Auckland to Tauranga to visit his love.
David and Phillipa married in August 1976. Their good communication, selflessness and commitment to each other was tested early on in their marriage.
"I think our biggest challenge was the birth of our first child, Derek who was born 16th August 1978," Phillipa says.
"The doctors knew straight away. They came in and said 'there's something wrong with your baby's eyes."
Until then, the couple had no idea David's blindness, caused by congenital glaucoma, was hereditary.
Phillipa says "David's mother was so rapt that he had found someone, she thought a genetic condition would put me off, so she said 'your babies will be fine'."
This lie meant Derek's diagnosis came as a shock, David admits.
"I found that really, really difficult. I had a lot of guilt," he says.
To make matters worse, Derek also had a condition called aniridia, where his irises did not work. To help protect his limited eyesight, he had to be kept inside darkened rooms for the first year of his life.
"We had to put blankets over the curtains because it wasn't dark enough," Phillipa says.
"I basically lived in a cage and I suffered post-natal depression. I was living in a cage physically and mentally too."
During this troubled time, the couple say their Christian faith helped.
To get outside, the family went for long walks in the evenings when the light was low.
Accepting Derek's condition for what it is was important, David says.
"I was feeling really guilty because all this was happening because of me but I started to realise my feeling wasn't logical. I got focused on my boy and said 'right, okay, it is what it is, what are we going to do about it?'
"People are willing to help you once they know the condition of your child. If you have a diagnosis, you can work with doctors and work through it," he says.
Derek had numerous surgeries on his eyes and, as he got older, he was able to venture outside with dark tinted glasses. He had just 20 per cent vision in only one eye but, now 40, his vision has not deteriorated further.
He was able to study and now has a successful career as a senior policy analyst.
David says one thing that really hurt him was friends suggesting the couple should not have any more children, in case they too had vision problems. "That was really tough."
The Seniors proved these people wrong by having three more children: Craig, now 38, was born with a hole in his heart but Paul and Abbey, now 34 and 31 respectively, were perfectly healthy. None of the three have glaucoma.
Family is still essential to the couple, and every Christmas they all gather together, now with three grandchildren in tow.
David says he came from a farming family, who were never very close. But he learnt the importance of family from Phillipa, who immigrated with her parents and two brothers from South Africa when she was just eight.
"There was just us… We always spent our holidays together," she says.
Phillipa's parents played a big role in the Seniors' life, including looking after the children as the couple moved up from Auckland to the Far North – first to a farm in Victoria Valley in 1993 before moving to Kaitaia.
The move north was facilitated by David's redundancy, losing his job with a film laboratory due to the changes in digital photography.
Despite the redundancy, David is proud of the work he did, particularly in the darkroom where his blindness was an asset.
"When I first started, the company had never employed people with a disability but after, they employed more blind people because they were so good at working in the darkroom."
The move north enabled the family to live a farming lifestyle.
When the couple moved to Kaitaia town in 2004, Phillipa began teaching piano and she has never had to advertise.
Music is a strong thread between the pair and they spend a lot of time listening to music or taking part in church worship.
Phillipa also enjoys reading to David. It was one of things that helped her through when she faced the greatest personal challenge in her life – first the loss of her father, then an injury car crash, followed by the loss of her mother.
"I just thought 'I'm an orphan' and I went through a huge depression. I had panic attacks: it was the worst thing," she says.
"I read The Hobbit to David. I thought if I couldn't remember what I had just read, at least he would remember."
David says the couple got through this challenge with support and commitment to each other.
"We've been through many things that could've ripped apart a marriage but we got through with communication and support for each other."
Phillipa says: "We stood before people and God and made our vows and we decided to stick with them. We said 'for richer and poorer, in sickness and in health' and we've had all of that."
The Seniors say Valentine's will probably be low-key.
Phillipa's favourite Valentine's Day gift from David is a soft-toy bear, complete with a love heart box, that she calls Valerie Valentine's.
"One year he bought me this series of fuzzy toys but he didn't give them to me all at once, I'd just find them in odd places around the house," she says.
David says with a smile that he knows what Phillipa loves: "My wife is someone who loves little gifts – that's her language of love.
"Preferring one another and looking out for each other, you soon learn what their language is," he says.
Phillipa retorts: "His language of love is touch and words of affirmation."
Marriage has changed both of them, for the better.
David admits before he married Phillipa, he was quite a selfish person. "I can remember after I lost my sight, I was using it to my advantage.
"My whole way of thinking has changed now. To me, it's about people out there, not me anymore. Any achievement, it's about giving back to the community," says David, who volunteers for a number of groups including a blind support group, Far North Budgeting Management and Te Hiku Sports Hub.
"It's a great thing; the whole marriage has done that to me. I can see the big picture stuff, rather than just my own self."
A couple who now act selflessly for each other and the community, who support each other through thick and thin – that truly is the language of love.