Hiya, with regards to loss of strength possibly due to the loss of muscle mass, I too have been concerned with this due to a cervical spinal cord injury that has switched off parts of most of my muscles from the neck down. I have adjusted by working out to maintain what little strength I had and, so far, I have noticed no negative difference in my strength or ability to do things that I could do before commencing HRT. Like with all aspects of transition, everyone responds differently, and many other factors play a part, such as lifestyle. I am an active person, so that may help, and I know If I become a couch potato, then I will deteriorate rapidly, so for me I must move and stretch continually. No rest for the wicked etc..
I think that because of the random way HRT affects people, the only way to find out, with medical supervision of course, is to try and see what happens. You can always stop and build your strength up later. It my also be wise to get some advice from a physiotherapist with regards to toning exrcises for the affected areas.
Another way to look at is is to look at the physique of female track athletes. Plenty of muscle mass going on there.
As for eyesight, I have noticed no difference yet.
Nikki