That sounds horrid. I am sorry that you are having such an unpleasant and worrying time. It is good to hear that your eyes are on the mend and I hope that remaining vision trouble resolves soon.
You are right that an employer is obliged to make ‘reasonable adjustments’ to help employees manage around their disability so that they can do their jobs despite the disability and stay in work. Are you ‘disabled’ under the meaning of the Equality Act 2010? I’m not sure whether you currently pass the test of your impairment caused by ON being both ‘substantial’ and ‘long-term’. Others might be better informed.
Those of us with an MS diagnosis are automatically considered ‘disabled’ under the Act - we share that doubtful privilege with people who have had a diagnosis of cancer or HIV. That I very much hope that you do not join this merry club goes without saying, but, if you do, automatic coverage under the Equality Act 2010 for the purposes of disability discrimination might be a small consolation prize. OK, so it wouldn’t really, would it?
But that’s all way down the line and won’t happen, with a bit of luck. The important thing now is to address the immediate problem that is being made harder to deal with by over-bright lighting at your workstation. My personal view is that your employers ought to jolly well find a way to help you. There is a difference between ‘it can’t be done’ and ‘it would be a mild pain in the arse to do, and we can’t be bothered’. If they are saying the latter, then I think they need a bit of a poke in the eye, if you will forgive the expression. Do you have an Occupational Health department at work? If so, talk to them - they should be clued up on employer best practice - by which I mean ‘how to be a decent employer and not a knob’ - regardless of whether you are technically disabled or not. They should know more about that than the typical overworked line boss. Ditto HR, another potential ally in the matter of helping you to do your job despite your eyes being wonky. What do they want you to do, go off sick when there’s no need?
In the meantime, take your sunglasses to work and wear them. It shows willing (always good) and also makes the point a bit (always good also). If you are feeling bashful, stick a notice on the back of your chair to say ‘I’m wearing these for my eyes, not because I’m an idiot’.