Although its clear you don't want to listen... Once again, with feeling.
Colour corrective - Not allowed, probably not for at least 10-20yrs (my guess)
Standard Glasses - Allowed
Contact lenses - Allowed, with caveats.
Laser Surgery - Allowed, with many caveats.
Why the difference ? Quite simply; safety standards and the Law.
Being able to see is important. A minimum visual acuity standard has been set. Sticking with standard glasses for a second all you need to do is read the chart and meet the standards. There are different standards for corrected and uncorrected vision. Glasses have been around for centuries. They are reliable, robust, consistent, clinically tested, and give an almost instant result. They work in all conditions and work for pretty much everyone. It is worth nothing that glasses also need to conform to various standards. We are not allowed Transition lenses or Multifocals. I believe that Bi-Focals are now allowed. You are also required to carry a second spare set just in case. All these things are important to ensure the person up the pointy end can see where they are going. Even if the train was automated there still needs to be someone up the front in case of emergencies. Sadly, as with all things, 'Life' takes over. At some point you may need glasses. Vision typically deteriorates with age. Imagine if your vision went and that Glasses were not allowed. How many Drivers would it take to run the railway ? How many people would you need to train up to constantly replace those going out because they can't see a few letters on a chart. All for the sake of a
horseshoe nail simple pair of specs. Glasses are a solution, they have minimal side effects and minimal costs. They work, awesome.
Contacts are one of those standards that have changed over time. When I joined they were banned. Part of the reason they were banned is because they aren't reliable. They have various side effects, don't work for everyone, fall out, are stupidly expensive, and have many many different types that any 'standard' would be unmanageable. Contact lenses have come a long way since they were invented. Society has also changed too. How and why they are used has changed over time. However. they are still a matter of choice so they are allowed but with caveats.
Laser has also changed over time. Gone are the days where you need months and months of recovery or might get your eyes blow up by incompetent surgery. In terms of railway history they have gone from banned, to only one type allowed, banned for new entrants only, to acceptable for everyone but with heavy heavy caveats. This has taken years. I'm a little under 20yrs in and it was banned before I started. As others have said; standards change over time. Laser still has risks but they are low. Low enough to be acceptable. Its also reached a stage where you can pop in on your lunch break and get your eyes done. The railway is a decent employer. If you lost your eyesight over time and got to the point where you didn't reach the standards, you would get paid off through medical capability. With Laser; you probably won't. Because it is considered to be an elective procedure, the risks are with the employee. A TOC can accept laser and all the additional costs involved but can still have clauses that allow the employee to be released at a moments notice if something went wrong. Maybe one day, laser surgery will be so reliable and safe that you don't have to declare it and a TOC would even pay for the procedure instead of paying for a second set of goggles. It is worth noting that your vision will still deteriorate and you may still need glasses in the future.
Colour corrective......
Exciting new technology for sure but still not quite there in terms of a clinical solution. Everything I read about these glasses seem prohibitive.
Due to the huge differences with colour blindness they are only suitable for a small number of people. They also have varying results for each person. In the article I linked there was a comment about waiting for 15 minutes to acclimatise to them before seeing a result. Normal glasses are great, put them on, take them off, not problems. There are also a couple of different types. Some will 'filter' different wavelengths of light and some will enhance the colours. I am also reading that they are incompatible with standard corrective lenses. So if you wore glasses or needed to in the future, your kinda screwed. They also work by filtering light. As it gets darker or brighter the effect changes. Imagine going through a tunnel and suddenly not being able to see the signals ahead. I'm also reading that they are very poor quality. They damage easily and therefore need to be replaced regularly. They are not 'sunglasses' either. So if you were at a point you needed to get you Ray Bans™ out. You then couldn't wear your colour filter lenses. Quite the reverse. They need bright light to work effectively :/
EnChroma, who seem to be the leading experts, say this about the Ishihara test.
Wearing tinted or colored lenses is not permitted on any color blindness test and will invalidate the result. A tinted lens may help with differentiation and seeing images in the Ishihara plate test, but would ultimately distort all colors making the colors you see appear incorrectly.
As a technology they appear to be purely aimed at the casual market. They are a luxury item and sold as a lifestyle benefit. They are not a clinical solution.
Again, Maybe one day. Just not today.
www.healthline.com
