I got in contact with RNIB's Eye Health Information Service after seeing this post, and this was their response:
"I do think this is odd recommendation. There is nothing specific around driving at night, legally, so discomfort may be an issue, and some people choose to stop night driving, but I tend to agree with him – if it’s a problem that limits his lifestyle, then referral may be indicated. Some patients are just more symptomatic than others.
"It is difficult because, as optometrists, we know that people we refer too early for surgery get rejected, and it’s then a waste of everyone’s time!
"The optometrist should be following NICE Guidance for cataract treatment. Section 1.2 of the guidance says clearly that the decision to refer for surgery should be based on a discussion of the impact the cataracts are having on your vision and quality life, and that access should not be restricted on the basis of visual acuity (the “ripeness” of the cataract) alone.
"Maybe suggesting he gets a second opinion from another optometrist or goes to his GP for referral would be the next step. If the consultant turns him down, then he is armed with the information he needs to fight his corner.
"That said there is always a risk for surgery so, if the cataracts are very small, they may be calculating that the benefits aren’t likely to be significant enough.
"If you can direct him to call the Eye Health Information Service to chat through indications for surgery, I’m sure we could help (0303 123 9999 Monday to Friday 8am to 8pm, and Saturday 9am to 1pm)."