Thinking of going to crossbow in low light situations can't see the deer anymore looking through peep sight and range pins any ideas

Larger peep, lighted pins. The newer fiber optic sights are amazing, shouldn't have any problems with light. How low light are you talking?

I'm 70 and use a 1/4" peep with a lighted pin, 1/2 hour before sun up to 1/2 hour after sundown works for me out to 25 yds.

have fibor optic pins the deer dont come out till last 15 min. of legal shooting like my mathews but these old eyes just cant focus guess the best option is a scope that gathers light  crossbow

There is a way to mount a scope on a bow. Don't ask me how they do it. But I knew a kid who was injured in Iraq and with glasses he is still legally blind. And someone at the VA found out about this and he can bowhunt again.

Nothing wrong in going to a crossbow if it is legal. I never really noticed it in practice but have had trouble focusing on both the pin and the deer at the same time when hunting. I limited myself to 35 yds with my bow and have been able to double that with a crossbow. I went with a Bowtech Stryker 380.

I got a 9pt buck the second week of the season with it, 77yds and he only went 20yds.

Use a peep . 1/4" to 3/16" it's good for low light , but larger (and with some folks 3/16) your focus starts to fail and have to focus on the deer or the pin as the other starts to blur a bit . Fiber optic sights are not created equal at all , might want to check out those options out as well .

On my PSE I tweaked the stock fiber optics on the pins. The stock pins only had a short curl of fiber optic. I bought some longer replacement fiber optic, put the tail ends in a small clear plastic tube and threaded that through the riser. I copied what I had seen on some other sights. It was a cheap alternative to buying a new sight and did help with gathering more light.

One other thing that makes a difference is if you are hunting from a pop up ground blind our some other box style blind you will loose your light sooner than if you were in the open or out of a tree stand.

What diameter fiber are you using in your sight? If .019, you might try pins with a .029 fiber instead. This will make them larger and brighter, along with a 1/4" peep it might work for you.

Consider or already taking supplements?

One example: http://www.visioncorrectionblog.com...provement/

My reply may look corny, silly, off-topic or perhaps tangential, but I am a believer (and I don't sell vitamins).

I used to pass around vitamins to my soldiers when we were out on our extended field-maneuvers; seeing those young men perk-up
after being worn-out was simply amazing! Like getting new batteries........

I still take them, plus I "dump" vitamin D3 with magnesium because we don't get enough sunlight.

Makes a big difference Sir!