Air carrier pilot reported numerous direct hit laser strikes while on approach affecting the crews night vision and causing a headache for one of the pilots.

Narrative

I was Pilot Monitoring; ZZZ1 to ZZZ2 descending on the ZZZZZ1 arrival cleared for the RNP XX. While on the arrival we were cleared to 6000 ft. and direct ZZZZZ2. As we descended I noticed a quick flash of a green laser at our 12 o'clock. It wasn't a direct hit; almost like they were sighting us in. It was so brief that I wasn't 100 percent sure that it was a laser. Nevertheless I immediately warned my Captain that we were being lasered from 12 o'clock and also reported it to Approach. Based on our position and altitude I initially reported that the laser came from the ridge line at our 12 o'clock. Approaching the ridge line we were hit a few more times and I suggested to my Captain that we turn off the lights so we couldn't be seen as easily; we did and I informed Approach that we were going dark. Once we turned the lights off the hits stopped.As we passed the ridge about 5 miles from ZZZZZ2 we figured the laser was behind us and turned the lights back on. We were immediately hit again with the green laser again from our 12 o'clock. This time the hits were precise. It was easier to see that the laser was coming from south of ZZZ3. I was surprised because we were between probably 15 to 20 miles from ZZZ3 when we turned the lights off initially; that was a powerful laser to reach us from that distance. Also why I mistook the strikes as coming from the ridge. These second series of strikes were accurate and persistent. I ducked my head below the glare-shield to block myself from the laser. We turned the lights back off and updated Approach on the laser origination. Turning the lights off helped with the accuracy but not persistency; they knew our general area and pointed the laser at us directly hitting us off and on consistently for several minutes. When we passed ZZZZZ3 the strikes stopped as the shooter was abeam our left side and slightly behind us. The good thing was at one point I got a somewhat accurate position on the location; the bad news was I took a hit. Inside ZZZZZ4 my Captain mentioned that he took a direct hit and that he was feeling the onset of a headache which made sense because he was on the side of the laser when we turned over ZZZZZ2. Despite taking a hit myself my night vision was still good and I didn't feel any adverse conditions so I offered to take control of the jet. He said he felt okay to land but wanted to let me know in case it got worse. I stood by ready to do so just in case. After landing we exited and made our way to the gate. I noticed on the ground that my night vision had suffered a little but was coming back. Approaching the gate my Captain said that in addition to the headache he felt a pain behind his right eye and requested that I called for paramedics to consult. I've been lasered before but never that aggressive and long. When police met the jet I shared with them the location off on my Jeppesen app as best I could tell. This is the 3rd strike I've had in the past 3 months. I really feel like we need some self evaluation guidance in our iPads or a protocol as these events are increasing. I've seen guidance and have read protocols from [other] airlines. As these events increase we need something.