It is height. Sights heights are measured above the dovetail. A .160 sight will protrude .160" above the slide, etc.
The mega dots are a large diameter dot. I have one and it is much more visible than the "standard" dot.
I like orange for tritium rings, and gold bead for non-tritium sights.

 

Thank you Squidsix for the information. I'll have to measure the current one.

 

.160 to .180 - there's scant little difference for my 70 year old eyes --- if you discuss a 6 oclock hold, the POint of impact will be up a tad but likely i'm not going to notice <15 yards. Now, .180 - a common sight height for Commander guns, to say .200 or .210 That's noticeable. Equally important to me is the amount of light on both sides of the front sight viewed through th erear.

 

Yep, it's the height. And I will say I love the MegaDot sights. Be aware that they are .140" wide, so if you have a pretty narrow rear notch it may tighten up your sight picture more than you want.

 

I might suggest checking out Dawson and their fiber optic sights - they offer green fiber options. In my experience a fiber front sight has been easier to see than any other style. Though I prefer red fiber I’ve seen the green and it seriously pops.

Couple that with black u-shaped rear sight and I think you’d have a winning combo.

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Not sure if this applies, but I had my eye doctor make me a set of what he calls "computer glasses". They are set with the focal distance at about arms length away. This is good for both reading a computer screen and also seeing my front sight much clearer. The downside is, the target becomes more blurry as I am near-sighted. But seeing my front sight clearly has improved my accuracy way more than seeing the target clearly and having my sights out of focus. You could even try a few of the cheap reading glasses at the dollar store and see if they make any difference at arms length for you. Just something to think about.

 

Same issue here to a degree. I found that some mild readers, like 1.0 diopter, are perfect.