'My parents didn't tell me I was blind until I was 17'

Casey at her revealing TED talk. She has ocular albinism, a genetic eye condition that causes permanent vision loss. Photo / TED talk

When I was growing up, I didn't know there was anything wrong with me. I wore glasses and was exceptionally clumsy, but my grades at school were no different to anyone else's. I had no idea that, in fact, I was legally blind - something I only discovered thanks to a fluke conversation when I turned 17.

I was at the eye specialist and casually mentioned I wanted to get my driver's licence. He looked surprised, then asked my parents why they hadn't told me the truth: I had ocular albinism, a genetic eye condition that causes permanent vision loss. I wouldn't be learning to drive - not that year, or ever.

It turns out my parents had known about my condition since I'd been diagnosed at six months old

That was almost three decades ago. I never have learnt to drive, but I haven't let my severe sight loss hold me back. I've held down a demanding job as a management consultant and now live with my husband and stepchildren in Dublin, where for the past 15 years I've worked as a disability campaigner.

A TED talk I gave encouraging business to value people with a disability has been viewed over two million times. And I've just launched a global campaign, #valuable, that is calling on businesses across the world to recognise the value of the one billion people living with disabilities.

It turns out my parents had known about my condition since I'd been diagnosed at six months old. They monitored it, but never told me about it. People often ask: were you angry with your parents? But I wasn't, and I have never questioned their decision.

All I remember is my mum crying as she admitted the truth. I think she was heartbroken she could no longer protect me from the reality. But my reaction was different: I simply couldn't take in the news. I'd lived 17 years of my life as a normal kid and couldn't relate to what I was being told.

I'd always coped, but over time things started to slot into place. (I can still make out shapes and I can see faces up close, but beyond 2ft, even wearing glasses, my world looks like an out-of-focus camera.)

I understood why I'm scared to walk into a room of people (because I can't see who they are), why I'm so bad at sports and why I'd have my nose against the screen when I'd watch TV. But I felt uncomfortable labelling myself disabled, so when I went to university then to business school I never discussed my condition with anyone - save for a few childhood friends.

My disability never hampered my social life, although I was always the 'loud' person in a group, which I think comes from compensating for my severe visual impairment. It was only when I was 28, and working as a management consultant for Accenture, that everything came crashing down.

I was too proud to use any visual aids, such as voice-activated software, and managed to hide my condition. But doing my job took so much effort that my confidence started to plummet and I finally decided to come out of the closet.

I went to see the head of HR and said, "I can't see and I need help." I was incredibly nervous and my heart was beating so fast, but as I told her my head felt lighter. It was that decision to truly accept my disability that kicked into action a whole series of events. My work organised for me to be assessed by specialists and a doctor, who told me I needed to take time off. I'd pushed myself to breaking point.

I took a year's sabbatical then left Accenture to set up a not-for-profit organisation to promote a positive image of disability, and I've never looked back. At this moment, I'm halfway through a 1,000km trek on horseback across Colombia to raise awareness of #valuable.

I still prefer not to ask for help unless I absolutely can't do something, and I've developed lots of coping mechanisms, such as searching for the bright light that reflects off my husband's head. But I've now found that balance between strength and vulnerability.