I read an article about Enchroma eyeglasses last year which said that some museums are stocking the glasses for the public to try. I had hoped to visit one of the museums this year to try the glasses before buying, even though they come with a money-back guarantee. Given the coronavirus, I doubt I'll be able to visit any of the museums for a while. The Enchroma website has a page which lists the museums, libraries, and state parks which have the eyeglasses available. Scroll down the following page to see the list of museums, etc:
It sounds like the OP's DH has deutan
colorblindness, and I believe my dad had the same type. Red, green, & brown all looked the same to him. It is the most common type of colorblindness, representing about 75% of those with colorblindness. I would love to have gotten the glasses for my dad to try, but he died a few years ago. He attempted to join the military during WWII in order to become a pilot, and that's when he found out he was colorblind. You can't become a pilot in the USA if you're colorblind.
Most other colorblind individuals have protan
colorblindness and that's what test results usually show for me. I generally don't confuse colors (with the exception that some purples look blue to me), but I may not see colors depending on the amount of light, background, & amount of color in the field. I didn't realize I was colorblind until shortly after I graduated from college. It explained the problems I had using microscopes for seeing cell structures when a red stain is typically used. I also had problems with colored chalk on blackboards, which I mistakenly assumed everyone had.
When I've taken online colorblind tests (not just Enchroma's test), the results are not consistent for me. I phoned Enchroma this week because of my inconsistent results. Over 50% of the time, my results state that I have moderate protan
colorblindness. But sometimes it says I'm severe protan
, mild protan
, moderate deutan
, or even normal color vision
. Enchroma's description of symptoms of protan
colorblindness are mostly consistent with my personal experience.
I suspect that the glasses wouldn't make as dramatic a difference for someone like me with protan
colorblindness versus someone with deutan
The woman I spoke with at Enchroma was very helpful. She recommended that I take the test on a computer screen instead of a tablet or phone. She said it's best if the room has diffused natural light rather than artificial light. There are also some controls you can adjust by clicking on the "stop" button on the upper left side of the test screen. She recommended under options setting the "Confidence Goal" to 97.5%. Default was 95%.
I also asked her if the same glasses are given to someone who is protan versus someone who is deutan. She said yes, but they also have a different lens for people who have "strong protan
There are also "Instructions" you can read. For example, it says to guess if you think you see a number but aren't certain. It also says that if you are wearing Enchroma glasses, the test results could be "worse" or "confusing".