Great pics of the Northen lights and Orca AR And bloody heck that's a bit of an injury to the eye (think you said 10 stiches). Hope it is on the mend - Bio-oil for scars like that my wife tells me.
Re the speedwork debate, then it is the elasticity of the tendons and ligaments that start to decline with age, much more rapidly than the engine loses power. The thing about speed work is that it demands more on elasticity side as the stride length is lengthend and there is more energy storage primarily in the achilles and hamstrings. The energy storage cause recoil and the calf should come more parallel to the ground and a higher knee lift.
So I don't think it is a case of avoidance, rather as other have said to workaround. Strides train the body to have elasitic action. Backing off the speedwork from maximum not only avoid injurys but speeds up recovery. Other than that there is volume versus speed - I'm now nicely at around 60 mpw off 5 runs. I do one hill session or tempo per week only if I feel up to it. Otherwise it is mainly easy miles.
Speedwork for me today - 5miles in 33:28 (6:42 pace) - It was my Marathon Talk race 2s faster than I planned it and had to run a slower last mile. It was backed off from max and my 14m MLR tomorrow can be comfortable. It kind of means that I am a long way from the Silver Comrades medal I'd ultimately like to win as something (expert vary) below 32:00 to 30:15 is indication of the potential for that.
Ultrasound showed nothing. In some way it is good as it means there is no obvious diesease. So I need to go to the doctor for the full result of the blood test as well and see if there is some answer to these pains.