Letter charts are not only used to measure visual acuity, they are also used as targets for subjective refraction. This is the main reason distance acuity is measured more often than near acuity. At a long distance, accommodation is relaxed, so that the refraction can be more accurate.
Popliteal artery. The popliteal artery branches off from the femoral artery. It is located in the knee and the back of the leg. Its courses near the adductor canal and the adductor hiatus, distinctive open areas inside the thigh. At its far end, it splits into the anterior and posterior tibial arteries. During its course, the popliteal artery branches into other significant blood vessels.
They join the posterior tibial veins in the upper calf. TIBIAL/PERONEAL TRUNK This short vein segment is located in the upper calf, where the posterior tibial and peroneal veins join. POPLITEAL (POP) The popliteal vein begins as the anterior tibial vein joins the tibial/peroneal trunk in the upper calf.